Jul. 15, 2024
Hi Richard, yes replacements are available, NOS at autojumbles and auction sites are often in the +0.010 increment intermediate sizes as the majority of pistons appear to be in the +0.020 increments. One of the piston ring suppliers like Cox and Turner should be able to help if you give them the details of the piston.
Question: Why is forged aluminum so strong?
Answer: Wiseco pistons and clutch baskets are forged from aerospace-grade aluminum for the ultimate in quality and strength. When aluminum is forged, the process compresses the material molecules closer together, making the aluminum denser and more resistant to impact and fatigue. The material properties improve in many aspects, including ultimate strength and ductility, which means the material will bend before it breaks. This is important for high performance race applications, where increases in horsepower and compression will stress the components much further than a stock engine.
Question: What is Wiseco ArmorGlide skirt coating?
Answer: Wiseco ArmorGlide skirt coating is a dry film lubricant applied to the piston skirt. This coating helps reduce friction, improving performance, and will also help quiet the piston in the cylinder bore. This coating is permanently applied, and is not a break in coating, it is on the piston for the life of the part.
Question: What is Wiseco ArmorPlating coating?
Answer: Wiseco ArmorPlating is applied to our RC series pistons, and select Sport Compact pistons. This high performance coating is applied to the piston crown, ring grooves, and piston pin bore. The coating on the dome helps protect the piston from the damage caused by detonation, and will actually harden over time from the heat caused by combustion. This coating is also applied to the ring groove, and helps eliminate micro-welding of the ring, and improve wear of the ring groove along with improving ring seal. The coating in the piston pin bore improves wear, reduces friction, and eliminates material deformation of the lockring groove.
Question: I just purchased a Wiseco Forged Performance clutch basket, are there any special things I need to do to install it?
Answer: Thank you for buying the best clutch basket available! Your clutch basket includes detailed instructions on how to install the basket on your vehicle. Once important thing to keep in mind is that the backing plate screws must be peened after they are installed, we cannot stress this enough! See your instruction sheet for details.
Question: There is no piston to wall clearance on the box label, what is the piston to wall clearance for my application?
Answer:
Powersports: Wiseco Powersports pistons are designed for optimal piston to wall clearance for the specific bore size of your engine. For example, your 125cc dirt bike engine is 54mm bore, the Wiseco piston is designed just for that bore size, and does not require any specific adjustments to fit properly.
Some applications, such as higher stressed race engines (or nitrous injected), forced induction engines (supercharged or turbos), do require additional piston to wall clearance than Wiseco has designed into the part. These are special applications that are normally built at high performance engine shops. These builders are familiar with the needs of these engines, and can help establish the needed engine set up parameters including piston to wall clearance. As a general rule, any high stress engines that include nitrous, turbo or supercharging, up to high pressure blowers require an additional .001 to .003 clearance.
Automotive: Wiseco pistons are designed with a special cam and barrel design. When measuring for piston to wall clearance, measure at widest point of piston skirt 1.300 from bottom of oil ring groove, 90 degrees from wrist pin hole. Refer to piston kit specification sheet for recommended piston to wall clearances.
COATED PISTONS Piston to wall clearance is calculated before the coating is applied to the piston skirts. Use the recommended bore diameter of the piston kit, and install the pistons to this bore size.
Automotive General Clearance Guidelines
Question: Which way do I install my new Wiseco piston, which direction does it face?
Answer: Your new Wiseco piston is marked on the top (crown) of the piston, indicating the direction. In most applications, the piston has an arrow intended to point toward the exhaust side of the engine (keep in mind this does not always mean the front of the vehicle).
The Wiseco V-twin piston line is marked in a similar manner, with an arrow indicating the exhaust side. Our Twin Cam piston line includes additional marking indicating the front position of the engine, if viewed from the seat of the bike.
Some Wiseco automotive pistons, such as the Sport Compact or LS series pistons, include a marking that indicates the front of the engine. The front of the engine typically means the cam chain or cam belt / water pump end of the engine. In a rear wheel drive car, this can literally mean the front of the car, and on a traverse engine install (such as a front wheel drive), this will mean the right side of the engine if viewed from the driver position.
Question: Does my outboard engine require any special piston adjustments or break-in when I use a Wiseco piston?
Answer: Outboard engines are very unique, in that the cooling system uses cold water from the lake or ocean. Because of this, the engine cylinder runs very cool as compared to many other engine types, and the piston does require more clearance to operate properly. Your Wiseco piston does have this additional clearance built into the design, and it is always best to follow the proper break in process. This is an extended process of heat cycling of the engine, and will ensure an extended piston life when followed. Refer to your OEM service manual for the proper break in for your engine, or you can also refer to our Marine catalog for general guidelines.
Question: My new Wiseco piston kit has flat rings, how do I know which direction the rings are installed?
Answer: Look closely at the ring near the ring end gap, and you will see a mark on the ring. This mark indicates the top side of the ring, so make sure that the ring is installed with this mark facing up. As a rule, if there is no marking, then the ring can be installed with any side facing up.
Question: Will Wiseco rings fit my OEM piston?
Answer: Wiseco rings and pistons are specifically designed and engineered to work together, and do not interchange with the OEM parts in most instances.
Question: What is the proper ring end gap for automotive engine?
Answer: Please reference the table below for our general automotive clearance guidelines.
Dongya contains other products and information you need, so please check it out.
Automotive General Clearance Guidelines
Question: What is the proper ring end gap for my 4-cycle engine?
Answer: Wiseco 4-cycle Powersports piston rings are designed with the proper end gap for most applications. Because 4-cycle engines contain two and three rings, the end gaps do require different values depending on the ring. This chart will help illustrate the minimum ring end gaps:
Top ring 2nd ring Oil rail
Most standard engines 0.004 0.005 0.015
Modified engines or Nitrous Oxide 0.005 0. 0.015
High performance racing 0. 0. 0.015
Racing with Nitrous / Turbo 0.006 0. 0.015
Blower / Forced induction 0.007 0. 0.015
Multiply your bore size in inches times the value on the table (to convert metric bore to inches, divide your metric bore x 25.4. For example, 77mm divided by 25.4 = 3., multiply this times the value on the chart).
Note: If your piston contains only a top ring and oil set, simply omit the second ring requirements
Question: What is the proper ring end gap for my 2-cycle engine?
Answer: Wiseco 2-cycle Powersports piston rings are designed with the proper end gap for most applications. However, Wiseco does recommend verifying the ring end gap when assembling your engine, as the end gap can affect the engine working properly if not set correctly. As a general rule, most engines will require .004 per inch of bore diameter for intended ring end gap minimum. More extreme engine applications, where the piston and ring will experience excessive heat, it is recommended to use .005 per inch of bore diameter ring end gap minimum. Generally, when measuring ring end gap, it is most always better to have too much than too little; a tight ring end gap can potentially cause the ring ends to touch during operation, which may cause a failure. Some marine and snowmobile engines do require additional clearance, so Wiseco does recommend additional allowance for these applications. See your Wiseco piston installation instructions included with the piston kit for more detail.
Question: How can I tell if my cylinder bore is Nikasil, cast iron, or chrome, and will Wiseco rings work in my cylinder?
Answer: Most modern Powersports engines use a Nikasil (Nickel Silicon) type of material plated onto the aluminum sub-material. Nikasil appears shiny (like chrome) when new, and is highly resistant to wear. All Wiseco rings are compatible with Nikasil, and will offer long service life and great sealing and performance.
Some other popular versions of Nikasil-like cylinder bore coatings can be called Electrofusion (Kawasaki) and Boron Composite (Suzuki). All Wiseco rings are compatible with these materials.
Some older model engines still use cast iron cylinder walls, which is a sleeve that is either inserted or cast into the cylinder. All Wiseco rings are compatible with cast iron sleeves. A cast iron sleeve will appear somewhat obvious, where the liner will be a different color than the cylinder, will appear to be a separate piece of the cylinder, and will attract a magnet.
Some older model engines use a chrome plated cylinder, and are becoming harder to find. A chrome cylinder can appear like a Nikasil cylinder, so it is always good to research your engine prior to installing a ring. Only some Wiseco rings are compatible with chrome plating. These ring types are normally non-coated, such as a cast iron ring face, to prevent the ring from scuffing the bore and not working properly.
Question: My engine bore is listed in millimeters, why are Wiseco ring end gaps listed in inches?
Answer: To convert your metric bore diameter to inches, grab your calculator and divide your millimeter bore by 25.4. The result will be inches, and then multiply this number by .004 (or .005 depending on your application), and the answer will be the minimum ring end gap. Here is an example of the math:
54mm bore divided by 25.4 = 2.
Multiply your bore size in inches times the value on the table (to convert metric bore to inches, divide your metric bore x 25.4. For example, 77mm divided by 25.4 = 3., multiply this times the value on the chart).
Question: How do I put together the oil ring assembly, it wants to fall apart and overlap when I try to install it?
Answer: Modern oil ring assemblies can be complex, and difficult to install, due to the delicate nature of the oil rails and the center separator. It is very important that the oil assembly be installed correctly on the piston, and collapsed into the cylinder, to operate correctly. It is always best to install the oil separator first, and then the bottom oil rail. Make sure that the oil separator is butted and not overlapped at the point, before installing the second oil rail. It is also a good practice to stagger the end gaps of the oil assembly pieces so that the rail and separator gaps do not line up, this will help ensure that the assembly stays together as the piston is installed.
One useful tip to try when assembling the rails onto the separator is to apply a dab of thick grease to the ends of the separator to hold the gaps in place.
Using a ring compressor is also important when installing the piston into the cylinder. This will help ensure that the oil assembly (and the top compression rings) will glide into the cylinder. Some engine builders are able to slide the piston assembly into the cylinder without a ring compressor; this method takes experience and patience.
Question: My new Wiseco 4-cycle piston kit has three rings, how do I know which ring goes where?
Answer: Most 4-cycle Powersports pistons use three rings, and knowing which ring goes where is critical. Generally, most top compression rings are steel alloy, and will appear shiny and bright, and will sometimes have a coating or treatment to the face of the ring. These coating could be industrial chrome (dull silver), gas nitride (bright silver), titanium nitride (gold), or moly filled (dark grey). Most rings will also have a top side marking, which is to be facing upward when installed.
Most second rings are of a cast iron material, though some can be steel. These are typically dark in color, and the face of the ring will be tapered. The ring will also have a top side marking, which is to be facing upward when installed.
Most Wiseco oil ring assemblies are three piece type, containing two oil rail rings and a center oil separator. These assemblies are delicate in nature, and can be tricky to install correctly. See our other FAQ questions for information on how to best install this type of ring.
Question: Why is there a pin in the ring groove on my Wiseco 2-cycle piston?
Answer: The pin located in the ring groove is important to the operation of your 2-cycle piston. The pin is known as a locating pin, and is meant to hold the ring end gap in place, preventing the ring from rotating in the cylinder bore. A 2-cycle engine has port windows located along the cylinder wall, and the ring end gap must be prevented from rotating into one of these port windows, and potentially snagging the ring. If this were to happen, the piston and ring will become damaged, along with the cylinder. It is critically important that the ring end gap be located over these locating pins when installing your new Wiseco piston.
Question: What is minimum piston to valve clearance?
Answer: Automotive: Most Wiseco pistons are machined with valve pockets that are deeper and larger than stock. These pockets provide adequate valve clearance under most conditions. It is very important that valve to piston clearance be checked upon piston installation. This is necessary due to many variations in cams, how much a block has been decked, or if the heads have been cut or angle milled.
Answer: Powersports: When assembling your 4-cycle engine, it is sometimes important to verify that you have adequate clearance from the piston to the valves. If you are installing an aftermarket racing camshaft, this becomes even more important to measure. The usual rule of thumb for piston to valve clearance is .080 intake side, and .100 exhaust side. These are relatively safe values that apply to most any engine. Some engine builders may cheat these values down to .060 intake and .080 exhaust, and Wiseco recommends discussing these lesser values with your camshaft supplier.
Question: Can you explain what a groove lock spacers is and how it is installed?
Answer: Whenever it is necessary to put the wrist pin bore into the oil ring groove, it is necessary to keep the oil ring end gaps from rotating and falling into the open pin bore. Wiseco developed and uses a dimpled spacer. The spacer is installed before the oil ring assembly, with the dimple down in the pin bore, to keep it from rotating.
Question: What are the Anti-detonation grooves on the top ring-land and the Pressure-grooves on the second land for?
Answer: The Anti-detonation grooves provide several advantages, which include further atomization of the combustion charge to prevent damage to the piston and ring caused by pre-ignition. These grooves also prevent carbon build up on the ring land which can cause the compression ring to stick in the ring groove.
The pressure seal groove will prevent gas build up below the top compression ring; these gases can cause the ring to lift from the ring groove. Unseating of the ring will result in compression losses and lower performance.
Question: How do you calculate compression ratio?
Answer: Compression ratio is the volume of the cylinder when the piston is at the bottom of the cylinder compared to where it is when the piston is at TDC. For example, a 100 cubic inch cylinder would have its volume squeezed into 10 cubic inches with a 10:1 ratio.
The easiest way to understand this is to think of everything as volumes that are stacked on top of one another. The elements that comprise this stack up are the displacement of the cylinder (bore and stroke), the volume of the deck clearance and the head gasket (which is basically a short-round cylinder), and the volume of the combustion chamber. The net combustion chamber volume is affected by the piston geometry, and this simply means you must subtract for a positive dome volume add for a piston dish volume.
Use the formula bore x bore x stroke x . x 16.4 to convert the cylinder volume to cubic centimeters (ccs). Stack up the cylinder + the deck volume + the gasket volume + the net chamber volume, and take this number and call it A. Next, stack up the deck, the gasket, and the net chamber volume and call it B. Lastly, divide the larger number A by the small number B, the result will be the compression ratio.
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¶ Pistons and Cylinders are pretty straight forward. After you take the head off try to move the piston, sideways, in the bore. There should be almost no movement. look at the cylinder. If there is an obvious ridge at the top of the cylinder and you can feel it with your finger, and there is piston movement sideways, you are going to have to bore it oversize. The factory oversizes are in quarter millimeter increments. Like .25,.50,.75,1.0 and the like. .25 mm is about .010". That's enough to clean up the bore, but it is not enough to increase the size of the engine by much. If you are unsure, measure the diameter of the bore and the diameter of the piston with inside and outside micrometers. Measure the piston about 1/2" up from the bottom of the piston skirt. Now measure the cylinder bore in several places at right angles to each other. Subtract piston diameter from the biggest bore diameter. This gives you the piston clearance. Piston clearance varies due to a number of factors.
If your old piston is within spec, and you want to reuse it, you will need to measure the ring side gap. Side clearance (gap) is measured with a feeler gauge, with the ring in it's groove in the piston. Just try to fit the feeler gauge between the ring and the top or bottom of the groove. They can be .001" to .003"(.025mm to .mm, check the manual). If you are using a new piston and rings you do not have to check this. If the gap is too much, even with new rings, you will need to replace the piston.
Everybody seems to think a new set of rings should cure everything. I wish it was true... but it's not. I would say 95 % of the time, on a dirt bike, you will need to bore it oversize. Sometimes, on a big street bike, the pistons will be within specification, but on most of the dirt bikes you are going to have to bore it.
It is best to have the cylinder bored on a boring machine. I have honed them as big as .040" over and I held it to spec on taper and out of roundness, but it took forever. Now, if I go bigger then 1/4mm or .010" I like to bore them on a machine. If you do try to hone them be sure to use a good hone like a Sunnen or Ammco. You will have to measure the piston and then bore the cyl to fit. Do not bore the cylinder unless you have the piston to measure. If you do, the clearance may be off.
Remove the circlip and push the wrist pin out with a screw driver. You may lightly tap it but if the pin is in too tight, you will need to pull it with a wristpin puller.
If the piston has seized and smeared aluminum on the cylinder you will need to remove it before you measure it. You can do this with Muriatic acid. Just take medicine dropper and put just a few drops on the aluminum that has been smeared in the cylinder. The acid will eat the aluminum but will not hurt the steel of the cylinder. DO NOT GET THE ACID ON YOU . If you do get it on yourself, water and baking soda will get it off. Also don't get it on any aluminum unless you want that aluminum eaten up. You can get Muriatic Acid at any home improvement store. They sell it buy the gallon, which will do about a billion cylinders. I'm not sure what they use it for... swimming pools or something. See the Acid Page.
OK, you and your buddy are charging up a hill, you can't let him beat you, can you? Of course not. So you really ran that puppy HOT and melted that Piston down good and proper. Drag it home, boiled off all that smeared aluminum, bored the Cylinder, put in new Pistons, Rings and all. Run it long enough that the rings should be seated and WOW. It just will not stop smoking. Now what?
You probably "Burnt" or "Scortched" the Cylinder. You got the metal in that Cylinder too hot and it took the temper out of the steel. The only real cure is a new Cylinder or Cylinder liner. Be sure and check the Cylinder head for flatness too. All that heat might have warped it. Beam me up, Scotty!
If you have a 2/stroke, be sure to look at the top of the piston. If it looks like a rat has been chewing on it watch out. It means that the bearings in the bottom end are starting to go. If you put in a new piston it will just be ruined as more bits of bearing shed by the lower crank and rod bearings. The cure? Rebuild the bottom end.
Be sure to check the cylinder for any rust pits. If there are any you will need to bore the cyl to a bigger over size to get rid of them. If you are restoring a machine, you will find these rust pits are wherever the rings stopped in the cylinder. A lot of water is created during combustion. Supposedly, about a gallon of water for every gallon of gas burned. Some of that water tends to collect around the rings.
When you get your cylinder back always ask if they cleaned it. Most places do but, you never know. To check, take a clean rag, put some fresh oil on it and wipe the inside of the cylinder with it. If it brings up any dirt, take your cylinder and wash it in lots of hot soapy water. Immediately dry and oil the cylinder so it will not rust.
The piston's rings must have a small gap between the ends when they are installed in the cylinder. This end gap is given in the shop manual and can vary quite a lot. Like .006" to .020"(.15mm to .08mm). End gap is measured by putting the ring to be measured in the cylinder and pushing it up with the piston to within 1/2" of the top of the cylinder. By pushing it with the piston, the ring is squared up in the cylinder bore. Now you can easily measure the end gap. If the gap is too small, file a bit on the end of the ring (Carefully!). Do only a little at a time, until you are within spec. If it is too big... well... ah... tough!
When I install a new Ring use I like to use a ring expander if I can. If you don't have one you can do it with your fingers, just be careful not to spread the Ring open too far or bend it sideways too much. Rings are very hard and brittle and break easily. Always install Rings with the markings on the rings up. A word here on rings. There are many different styles and types of Rings. Dykes, Keystone, Standard, you name it. You must replace any Ring with the same type and size. Some people think that the spring pressure exerted by the Ring on the cylinder walls is what seals in the combustion pressure. That is not true.
Think about it. Combustion produces several thousands of pounds of pressure. You can compress the ring with one hand, right? It is that combustion pressure itself that channels down between the piston and ring, pushing the ring against the cyl wall. So don't put a .5 over ring in a .25 over cylinder and think you are helping, your not. In fact, that Ring will not contact the cylinder wall right. So you could be losing compression. Another thing, after you install all the Rings, with the markings up, stagger the Ring end gaps about 1/3 or 1/2 apart so the gaps are not in line with each other. If you have a 3 piece Oil Ring stagger them this way. On four strokes, you can have a one piece oil Ring or a three piece oil ring. the three piece ones seem to work better but are harder to get in the cylinder.
Before you install the Piston, oil the Piston and cylinder up real good. Move the Rings around in their grooves and make sure there is plenty of oil on all the parts. Now you are ready to install the Piston. Pistons do have a front and a back. If there is a mark or arrow on the Piston it always goes to the front or exhaust side. On 4/strokes there may just be an "IN" in one of the valve pockets. This goes to the intake side. (Duh!) On most cylinders I like to use a Ring Compressor. There are lots of different types of ring compressors. You can even use a regular hose clamp.
The piston and rings should go on smoothly with just a little tap with a piece of wood. They say you should be able to push the piston and rings on with your thumbs... but I never can. Bad thumbs I guess. So I use a bit of wood or a lead hammer and very gently tap it in. Do not force it. If it just will not go, reposition the ring compressor. With 3 piece oil rings you just about have to use a ring compressor. If the cylinder is a big port 2/stroke you may have to reach in through the intake port, with a long thin screw driver, and push the Ring so it does not get caught in the port. Also remember, on a 2/stroke, to position the Ring ends to the peg in each ring groove.
I like to put the piston with rings and one circlip installed, in from the top of the cylinder and push it down till the wrist pin hole is uncovered. Then I slide the cyl down to the rod (and bearing on a 2/stroke) and then push in the wrist pin. Install the circlip and push the cyl the rest of the way down. Don't forget the base gasket and sometimes a base o-ring. Before I install the circlip I like to put a rag in any hole the circlip could go down if it gets away from me during instillation. I always use new wrist pins, wristpin bearings, and circlips, although I can live with reusing a circlip. Replace with new, everything else.
Circlips come in a number of different flavors, but about 95% of the motorcycle pistons out there are of the wire type. Older Harley Davidsons used their own funny circlip that required a special tool to install. Newer HD models and aftermarket HD pistons are sort of coming around to the wire type. If you are not sure of the type, check with the manufacturer. Circlips are NOT interchangeable between types. DO NOT just pick anything and jam it in there. Use the type the manufacturer of the piston recommends. If the circlip fails and allows the wrist pin to hit the cylinder walls, bad things will happen. Back in the 60s and 70s some of the high performance builders used Teflon or aluminum "Buttons" in place of circlips, but that has fallen out of favor and no one seems to use them anymore.
Two, three and four cylinder engines usually have the crank pins staggered so you can put the pistons in one or two at a time... makes for lots of fun. Go slow and they will go in.
Piston oversizes are usually marked on the piston. Trouble is, sometimes the markings are printed on with ink and not stamped in or they are worn off. If the oversize is marked on the piston, it can be in thousands of an inch, like this .020" oversize piston or in quarters of a millimeter, like this 0.50 mm oversize piston. Then, just to make it interesting, there can also be a code stamped in the piston top. This code number tells what oversize the piston is and what type of rings are used. I always measure the old piston so I can order the right oversize.
It seems all the rage now to have sleeveless plated cylinders. Sometimes, it's called Chrome Plating, Nikasil, Electrofusion, Boron Composite, SCEM Composite, Ceramic Composite, or who knows what. These cylinders are bored to the right size and then plated. The pistons use a softer metal than the plating for the rings. The idea being the rings will wear and the cylinder will not. It's been my observation that this is not always true. I've seen what sure looked like wear to me, in more than one plated cylinder. Granted, it's not quite as bad as a steel cylinder but... ! If a plated cylinder is damaged, you will need to bore it out big and press a new steel liner into it. Then bore the new sleeve to the right size for a new piston.
If the damage is not too bad, you may be able to have the damaged cylinder replated. I think this is just a high tech way of doing things on the cheap. One thing to remember. On Chrome Plated cylinders you MUST use cast iron rings and NOT chrome rings. If you use chrome rings on a Chrome Plated cylinder, things do not wear so well. It will start pealing the chrome off. You can use chrome rings on Nikasil, Electrofusion, Boron Composite and some others. Check with the ring's manufacturer to be sure. I gotta admit, plating does work good if you never seize an engine up, and we would never do that, would we?
Something to remember, if you are working on an old bike and are having trouble finding a piston. As long as the wrist pin diameter is the same and you can bore the cyl to fit it. Almost any piston will work. You might have to cut the piston skirt down or drill big ports in it. You might have to grind the piston head to fit the combustion chamber or grind inside the skirt to make it the right weight, but with some imagination you can make it fit and it will work.
For example, in High School I used to take a Honda 175cc twin cylinder piston and make it work in my CT-90 engine. I would bore the cylinder out because the 175 piston (52mm) was bigger in diameter then the 90cc piston (50mm). It also had a much higher piston crown. I would put the valves in the cylinder head and then lay a piece of carbon paper on it with the carbon toward the piston. I then pressed the top of the piston into the combustion chamber and wiggled it about. The spots on the piston from the carbon paper are the high spots.
I then took a hand file and filed off the carbon marks, moved the carbon paper around, rub the piston again, and file some more. I would mark and file until no marks showed up. I would then file just a bit more. I then assembled the engine with a small piece of clay on the piston. Turn the engine over and then measure the thickness of the clay. That told me how much clearance there was between the piston and the cylinder head. You need about .040" of an inch clearance. My 90 was stroked so I had to cut down the piston skirt too. The wrist pin was the same diameter as the 90 so I was in. Why did I do all this when CT-90 pistons are easy to get? Well, it gave me a measured 13.8 to 1 compression ratio. As long as I could get high octaine gas I could fly! The point is, if you can't find the right piston, lots of times, you can make another one fit.
You will find that some pistons look kind of weird. This is because engine designers are always trying to get a bit more horsepower out of the engine. Check these pistons out.
Wow, I guess there is a bit more to pistons then I first thought.
Hi Richard, yes replacements are available, NOS at autojumbles and auction sites are often in the +0.010 increment intermediate sizes as the majority of pistons appear to be in the +0.020 increments. One of the piston ring suppliers like Cox and Turner should be able to help if you give them the details of the piston.
Question: Why is forged aluminum so strong?
Answer: Wiseco pistons and clutch baskets are forged from aerospace-grade aluminum for the ultimate in quality and strength. When aluminum is forged, the process compresses the material molecules closer together, making the aluminum denser and more resistant to impact and fatigue. The material properties improve in many aspects, including ultimate strength and ductility, which means the material will bend before it breaks. This is important for high performance race applications, where increases in horsepower and compression will stress the components much further than a stock engine.
Question: What is Wiseco ArmorGlide skirt coating?
Answer: Wiseco ArmorGlide skirt coating is a dry film lubricant applied to the piston skirt. This coating helps reduce friction, improving performance, and will also help quiet the piston in the cylinder bore. This coating is permanently applied, and is not a break in coating, it is on the piston for the life of the part.
Question: What is Wiseco ArmorPlating coating?
Answer: Wiseco ArmorPlating is applied to our RC series pistons, and select Sport Compact pistons. This high performance coating is applied to the piston crown, ring grooves, and piston pin bore. The coating on the dome helps protect the piston from the damage caused by detonation, and will actually harden over time from the heat caused by combustion. This coating is also applied to the ring groove, and helps eliminate micro-welding of the ring, and improve wear of the ring groove along with improving ring seal. The coating in the piston pin bore improves wear, reduces friction, and eliminates material deformation of the lockring groove.
Question: I just purchased a Wiseco Forged Performance clutch basket, are there any special things I need to do to install it?
Answer: Thank you for buying the best clutch basket available! Your clutch basket includes detailed instructions on how to install the basket on your vehicle. Once important thing to keep in mind is that the backing plate screws must be peened after they are installed, we cannot stress this enough! See your instruction sheet for details.
Question: There is no piston to wall clearance on the box label, what is the piston to wall clearance for my application?
Answer:
Powersports: Wiseco Powersports pistons are designed for optimal piston to wall clearance for the specific bore size of your engine. For example, your 125cc dirt bike engine is 54mm bore, the Wiseco piston is designed just for that bore size, and does not require any specific adjustments to fit properly.
Some applications, such as higher stressed race engines (or nitrous injected), forced induction engines (supercharged or turbos), do require additional piston to wall clearance than Wiseco has designed into the part. These are special applications that are normally built at high performance engine shops. These builders are familiar with the needs of these engines, and can help establish the needed engine set up parameters including piston to wall clearance. As a general rule, any high stress engines that include nitrous, turbo or supercharging, up to high pressure blowers require an additional .001 to .003 clearance.
Automotive: Wiseco pistons are designed with a special cam and barrel design. When measuring for piston to wall clearance, measure at widest point of piston skirt 1.300 from bottom of oil ring groove, 90 degrees from wrist pin hole. Refer to piston kit specification sheet for recommended piston to wall clearances.
COATED PISTONS Piston to wall clearance is calculated before the coating is applied to the piston skirts. Use the recommended bore diameter of the piston kit, and install the pistons to this bore size.
Automotive General Clearance Guidelines
Question: Which way do I install my new Wiseco piston, which direction does it face?
Answer: Your new Wiseco piston is marked on the top (crown) of the piston, indicating the direction. In most applications, the piston has an arrow intended to point toward the exhaust side of the engine (keep in mind this does not always mean the front of the vehicle).
The Wiseco V-twin piston line is marked in a similar manner, with an arrow indicating the exhaust side. Our Twin Cam piston line includes additional marking indicating the front position of the engine, if viewed from the seat of the bike.
Some Wiseco automotive pistons, such as the Sport Compact or LS series pistons, include a marking that indicates the front of the engine. The front of the engine typically means the cam chain or cam belt / water pump end of the engine. In a rear wheel drive car, this can literally mean the front of the car, and on a traverse engine install (such as a front wheel drive), this will mean the right side of the engine if viewed from the driver position.
Question: Does my outboard engine require any special piston adjustments or break-in when I use a Wiseco piston?
Answer: Outboard engines are very unique, in that the cooling system uses cold water from the lake or ocean. Because of this, the engine cylinder runs very cool as compared to many other engine types, and the piston does require more clearance to operate properly. Your Wiseco piston does have this additional clearance built into the design, and it is always best to follow the proper break in process. This is an extended process of heat cycling of the engine, and will ensure an extended piston life when followed. Refer to your OEM service manual for the proper break in for your engine, or you can also refer to our Marine catalog for general guidelines.
Question: My new Wiseco piston kit has flat rings, how do I know which direction the rings are installed?
Answer: Look closely at the ring near the ring end gap, and you will see a mark on the ring. This mark indicates the top side of the ring, so make sure that the ring is installed with this mark facing up. As a rule, if there is no marking, then the ring can be installed with any side facing up.
Question: Will Wiseco rings fit my OEM piston?
Answer: Wiseco rings and pistons are specifically designed and engineered to work together, and do not interchange with the OEM parts in most instances.
Question: What is the proper ring end gap for automotive engine?
Answer: Please reference the table below for our general automotive clearance guidelines.
Dongya contains other products and information you need, so please check it out.
Automotive General Clearance Guidelines
Question: What is the proper ring end gap for my 4-cycle engine?
Answer: Wiseco 4-cycle Powersports piston rings are designed with the proper end gap for most applications. Because 4-cycle engines contain two and three rings, the end gaps do require different values depending on the ring. This chart will help illustrate the minimum ring end gaps:
Top ring 2nd ring Oil rail
Most standard engines 0.004 0.005 0.015
Modified engines or Nitrous Oxide 0.005 0. 0.015
High performance racing 0. 0. 0.015
Racing with Nitrous / Turbo 0.006 0. 0.015
Blower / Forced induction 0.007 0. 0.015
Multiply your bore size in inches times the value on the table (to convert metric bore to inches, divide your metric bore x 25.4. For example, 77mm divided by 25.4 = 3., multiply this times the value on the chart).
Note: If your piston contains only a top ring and oil set, simply omit the second ring requirements
Question: What is the proper ring end gap for my 2-cycle engine?
Answer: Wiseco 2-cycle Powersports piston rings are designed with the proper end gap for most applications. However, Wiseco does recommend verifying the ring end gap when assembling your engine, as the end gap can affect the engine working properly if not set correctly. As a general rule, most engines will require .004 per inch of bore diameter for intended ring end gap minimum. More extreme engine applications, where the piston and ring will experience excessive heat, it is recommended to use .005 per inch of bore diameter ring end gap minimum. Generally, when measuring ring end gap, it is most always better to have too much than too little; a tight ring end gap can potentially cause the ring ends to touch during operation, which may cause a failure. Some marine and snowmobile engines do require additional clearance, so Wiseco does recommend additional allowance for these applications. See your Wiseco piston installation instructions included with the piston kit for more detail.
Question: How can I tell if my cylinder bore is Nikasil, cast iron, or chrome, and will Wiseco rings work in my cylinder?
Answer: Most modern Powersports engines use a Nikasil (Nickel Silicon) type of material plated onto the aluminum sub-material. Nikasil appears shiny (like chrome) when new, and is highly resistant to wear. All Wiseco rings are compatible with Nikasil, and will offer long service life and great sealing and performance.
Some other popular versions of Nikasil-like cylinder bore coatings can be called Electrofusion (Kawasaki) and Boron Composite (Suzuki). All Wiseco rings are compatible with these materials.
Some older model engines still use cast iron cylinder walls, which is a sleeve that is either inserted or cast into the cylinder. All Wiseco rings are compatible with cast iron sleeves. A cast iron sleeve will appear somewhat obvious, where the liner will be a different color than the cylinder, will appear to be a separate piece of the cylinder, and will attract a magnet.
Some older model engines use a chrome plated cylinder, and are becoming harder to find. A chrome cylinder can appear like a Nikasil cylinder, so it is always good to research your engine prior to installing a ring. Only some Wiseco rings are compatible with chrome plating. These ring types are normally non-coated, such as a cast iron ring face, to prevent the ring from scuffing the bore and not working properly.
Question: My engine bore is listed in millimeters, why are Wiseco ring end gaps listed in inches?
Answer: To convert your metric bore diameter to inches, grab your calculator and divide your millimeter bore by 25.4. The result will be inches, and then multiply this number by .004 (or .005 depending on your application), and the answer will be the minimum ring end gap. Here is an example of the math:
54mm bore divided by 25.4 = 2.
Multiply your bore size in inches times the value on the table (to convert metric bore to inches, divide your metric bore x 25.4. For example, 77mm divided by 25.4 = 3., multiply this times the value on the chart).
Question: How do I put together the oil ring assembly, it wants to fall apart and overlap when I try to install it?
Answer: Modern oil ring assemblies can be complex, and difficult to install, due to the delicate nature of the oil rails and the center separator. It is very important that the oil assembly be installed correctly on the piston, and collapsed into the cylinder, to operate correctly. It is always best to install the oil separator first, and then the bottom oil rail. Make sure that the oil separator is butted and not overlapped at the point, before installing the second oil rail. It is also a good practice to stagger the end gaps of the oil assembly pieces so that the rail and separator gaps do not line up, this will help ensure that the assembly stays together as the piston is installed.
One useful tip to try when assembling the rails onto the separator is to apply a dab of thick grease to the ends of the separator to hold the gaps in place.
Using a ring compressor is also important when installing the piston into the cylinder. This will help ensure that the oil assembly (and the top compression rings) will glide into the cylinder. Some engine builders are able to slide the piston assembly into the cylinder without a ring compressor; this method takes experience and patience.
Question: My new Wiseco 4-cycle piston kit has three rings, how do I know which ring goes where?
Answer: Most 4-cycle Powersports pistons use three rings, and knowing which ring goes where is critical. Generally, most top compression rings are steel alloy, and will appear shiny and bright, and will sometimes have a coating or treatment to the face of the ring. These coating could be industrial chrome (dull silver), gas nitride (bright silver), titanium nitride (gold), or moly filled (dark grey). Most rings will also have a top side marking, which is to be facing upward when installed.
Most second rings are of a cast iron material, though some can be steel. These are typically dark in color, and the face of the ring will be tapered. The ring will also have a top side marking, which is to be facing upward when installed.
Most Wiseco oil ring assemblies are three piece type, containing two oil rail rings and a center oil separator. These assemblies are delicate in nature, and can be tricky to install correctly. See our other FAQ questions for information on how to best install this type of ring.
Question: Why is there a pin in the ring groove on my Wiseco 2-cycle piston?
Answer: The pin located in the ring groove is important to the operation of your 2-cycle piston. The pin is known as a locating pin, and is meant to hold the ring end gap in place, preventing the ring from rotating in the cylinder bore. A 2-cycle engine has port windows located along the cylinder wall, and the ring end gap must be prevented from rotating into one of these port windows, and potentially snagging the ring. If this were to happen, the piston and ring will become damaged, along with the cylinder. It is critically important that the ring end gap be located over these locating pins when installing your new Wiseco piston.
Question: What is minimum piston to valve clearance?
Answer: Automotive: Most Wiseco pistons are machined with valve pockets that are deeper and larger than stock. These pockets provide adequate valve clearance under most conditions. It is very important that valve to piston clearance be checked upon piston installation. This is necessary due to many variations in cams, how much a block has been decked, or if the heads have been cut or angle milled.
Answer: Powersports: When assembling your 4-cycle engine, it is sometimes important to verify that you have adequate clearance from the piston to the valves. If you are installing an aftermarket racing camshaft, this becomes even more important to measure. The usual rule of thumb for piston to valve clearance is .080 intake side, and .100 exhaust side. These are relatively safe values that apply to most any engine. Some engine builders may cheat these values down to .060 intake and .080 exhaust, and Wiseco recommends discussing these lesser values with your camshaft supplier.
Question: Can you explain what a groove lock spacers is and how it is installed?
Answer: Whenever it is necessary to put the wrist pin bore into the oil ring groove, it is necessary to keep the oil ring end gaps from rotating and falling into the open pin bore. Wiseco developed and uses a dimpled spacer. The spacer is installed before the oil ring assembly, with the dimple down in the pin bore, to keep it from rotating.
Question: What are the Anti-detonation grooves on the top ring-land and the Pressure-grooves on the second land for?
Answer: The Anti-detonation grooves provide several advantages, which include further atomization of the combustion charge to prevent damage to the piston and ring caused by pre-ignition. These grooves also prevent carbon build up on the ring land which can cause the compression ring to stick in the ring groove.
The pressure seal groove will prevent gas build up below the top compression ring; these gases can cause the ring to lift from the ring groove. Unseating of the ring will result in compression losses and lower performance.
Question: How do you calculate compression ratio?
Answer: Compression ratio is the volume of the cylinder when the piston is at the bottom of the cylinder compared to where it is when the piston is at TDC. For example, a 100 cubic inch cylinder would have its volume squeezed into 10 cubic inches with a 10:1 ratio.
The easiest way to understand this is to think of everything as volumes that are stacked on top of one another. The elements that comprise this stack up are the displacement of the cylinder (bore and stroke), the volume of the deck clearance and the head gasket (which is basically a short-round cylinder), and the volume of the combustion chamber. The net combustion chamber volume is affected by the piston geometry, and this simply means you must subtract for a positive dome volume add for a piston dish volume.
Use the formula bore x bore x stroke x . x 16.4 to convert the cylinder volume to cubic centimeters (ccs). Stack up the cylinder + the deck volume + the gasket volume + the net chamber volume, and take this number and call it A. Next, stack up the deck, the gasket, and the net chamber volume and call it B. Lastly, divide the larger number A by the small number B, the result will be the compression ratio.
Contact us to discuss your requirements of Motorcycle Piston Rings Suppliers. Our experienced sales team can help you identify the options that best suit your needs.
¶ Pistons and Cylinders are pretty straight forward. After you take the head off try to move the piston, sideways, in the bore. There should be almost no movement. look at the cylinder. If there is an obvious ridge at the top of the cylinder and you can feel it with your finger, and there is piston movement sideways, you are going to have to bore it oversize. The factory oversizes are in quarter millimeter increments. Like .25,.50,.75,1.0 and the like. .25 mm is about .010". That's enough to clean up the bore, but it is not enough to increase the size of the engine by much. If you are unsure, measure the diameter of the bore and the diameter of the piston with inside and outside micrometers. Measure the piston about 1/2" up from the bottom of the piston skirt. Now measure the cylinder bore in several places at right angles to each other. Subtract piston diameter from the biggest bore diameter. This gives you the piston clearance. Piston clearance varies due to a number of factors.
If your old piston is within spec, and you want to reuse it, you will need to measure the ring side gap. Side clearance (gap) is measured with a feeler gauge, with the ring in it's groove in the piston. Just try to fit the feeler gauge between the ring and the top or bottom of the groove. They can be .001" to .003"(.025mm to .mm, check the manual). If you are using a new piston and rings you do not have to check this. If the gap is too much, even with new rings, you will need to replace the piston.
Everybody seems to think a new set of rings should cure everything. I wish it was true... but it's not. I would say 95 % of the time, on a dirt bike, you will need to bore it oversize. Sometimes, on a big street bike, the pistons will be within specification, but on most of the dirt bikes you are going to have to bore it.
It is best to have the cylinder bored on a boring machine. I have honed them as big as .040" over and I held it to spec on taper and out of roundness, but it took forever. Now, if I go bigger then 1/4mm or .010" I like to bore them on a machine. If you do try to hone them be sure to use a good hone like a Sunnen or Ammco. You will have to measure the piston and then bore the cyl to fit. Do not bore the cylinder unless you have the piston to measure. If you do, the clearance may be off.
Remove the circlip and push the wrist pin out with a screw driver. You may lightly tap it but if the pin is in too tight, you will need to pull it with a wristpin puller.
If the piston has seized and smeared aluminum on the cylinder you will need to remove it before you measure it. You can do this with Muriatic acid. Just take medicine dropper and put just a few drops on the aluminum that has been smeared in the cylinder. The acid will eat the aluminum but will not hurt the steel of the cylinder. DO NOT GET THE ACID ON YOU . If you do get it on yourself, water and baking soda will get it off. Also don't get it on any aluminum unless you want that aluminum eaten up. You can get Muriatic Acid at any home improvement store. They sell it buy the gallon, which will do about a billion cylinders. I'm not sure what they use it for... swimming pools or something. See the Acid Page.
OK, you and your buddy are charging up a hill, you can't let him beat you, can you? Of course not. So you really ran that puppy HOT and melted that Piston down good and proper. Drag it home, boiled off all that smeared aluminum, bored the Cylinder, put in new Pistons, Rings and all. Run it long enough that the rings should be seated and WOW. It just will not stop smoking. Now what?
You probably "Burnt" or "Scortched" the Cylinder. You got the metal in that Cylinder too hot and it took the temper out of the steel. The only real cure is a new Cylinder or Cylinder liner. Be sure and check the Cylinder head for flatness too. All that heat might have warped it. Beam me up, Scotty!
If you have a 2/stroke, be sure to look at the top of the piston. If it looks like a rat has been chewing on it watch out. It means that the bearings in the bottom end are starting to go. If you put in a new piston it will just be ruined as more bits of bearing shed by the lower crank and rod bearings. The cure? Rebuild the bottom end.
Be sure to check the cylinder for any rust pits. If there are any you will need to bore the cyl to a bigger over size to get rid of them. If you are restoring a machine, you will find these rust pits are wherever the rings stopped in the cylinder. A lot of water is created during combustion. Supposedly, about a gallon of water for every gallon of gas burned. Some of that water tends to collect around the rings.
When you get your cylinder back always ask if they cleaned it. Most places do but, you never know. To check, take a clean rag, put some fresh oil on it and wipe the inside of the cylinder with it. If it brings up any dirt, take your cylinder and wash it in lots of hot soapy water. Immediately dry and oil the cylinder so it will not rust.
The piston's rings must have a small gap between the ends when they are installed in the cylinder. This end gap is given in the shop manual and can vary quite a lot. Like .006" to .020"(.15mm to .08mm). End gap is measured by putting the ring to be measured in the cylinder and pushing it up with the piston to within 1/2" of the top of the cylinder. By pushing it with the piston, the ring is squared up in the cylinder bore. Now you can easily measure the end gap. If the gap is too small, file a bit on the end of the ring (Carefully!). Do only a little at a time, until you are within spec. If it is too big... well... ah... tough!
When I install a new Ring use I like to use a ring expander if I can. If you don't have one you can do it with your fingers, just be careful not to spread the Ring open too far or bend it sideways too much. Rings are very hard and brittle and break easily. Always install Rings with the markings on the rings up. A word here on rings. There are many different styles and types of Rings. Dykes, Keystone, Standard, you name it. You must replace any Ring with the same type and size. Some people think that the spring pressure exerted by the Ring on the cylinder walls is what seals in the combustion pressure. That is not true.
Think about it. Combustion produces several thousands of pounds of pressure. You can compress the ring with one hand, right? It is that combustion pressure itself that channels down between the piston and ring, pushing the ring against the cyl wall. So don't put a .5 over ring in a .25 over cylinder and think you are helping, your not. In fact, that Ring will not contact the cylinder wall right. So you could be losing compression. Another thing, after you install all the Rings, with the markings up, stagger the Ring end gaps about 1/3 or 1/2 apart so the gaps are not in line with each other. If you have a 3 piece Oil Ring stagger them this way. On four strokes, you can have a one piece oil Ring or a three piece oil ring. the three piece ones seem to work better but are harder to get in the cylinder.
Before you install the Piston, oil the Piston and cylinder up real good. Move the Rings around in their grooves and make sure there is plenty of oil on all the parts. Now you are ready to install the Piston. Pistons do have a front and a back. If there is a mark or arrow on the Piston it always goes to the front or exhaust side. On 4/strokes there may just be an "IN" in one of the valve pockets. This goes to the intake side. (Duh!) On most cylinders I like to use a Ring Compressor. There are lots of different types of ring compressors. You can even use a regular hose clamp.
The piston and rings should go on smoothly with just a little tap with a piece of wood. They say you should be able to push the piston and rings on with your thumbs... but I never can. Bad thumbs I guess. So I use a bit of wood or a lead hammer and very gently tap it in. Do not force it. If it just will not go, reposition the ring compressor. With 3 piece oil rings you just about have to use a ring compressor. If the cylinder is a big port 2/stroke you may have to reach in through the intake port, with a long thin screw driver, and push the Ring so it does not get caught in the port. Also remember, on a 2/stroke, to position the Ring ends to the peg in each ring groove.
I like to put the piston with rings and one circlip installed, in from the top of the cylinder and push it down till the wrist pin hole is uncovered. Then I slide the cyl down to the rod (and bearing on a 2/stroke) and then push in the wrist pin. Install the circlip and push the cyl the rest of the way down. Don't forget the base gasket and sometimes a base o-ring. Before I install the circlip I like to put a rag in any hole the circlip could go down if it gets away from me during instillation. I always use new wrist pins, wristpin bearings, and circlips, although I can live with reusing a circlip. Replace with new, everything else.
Circlips come in a number of different flavors, but about 95% of the motorcycle pistons out there are of the wire type. Older Harley Davidsons used their own funny circlip that required a special tool to install. Newer HD models and aftermarket HD pistons are sort of coming around to the wire type. If you are not sure of the type, check with the manufacturer. Circlips are NOT interchangeable between types. DO NOT just pick anything and jam it in there. Use the type the manufacturer of the piston recommends. If the circlip fails and allows the wrist pin to hit the cylinder walls, bad things will happen. Back in the 60s and 70s some of the high performance builders used Teflon or aluminum "Buttons" in place of circlips, but that has fallen out of favor and no one seems to use them anymore.
Two, three and four cylinder engines usually have the crank pins staggered so you can put the pistons in one or two at a time... makes for lots of fun. Go slow and they will go in.
Piston oversizes are usually marked on the piston. Trouble is, sometimes the markings are printed on with ink and not stamped in or they are worn off. If the oversize is marked on the piston, it can be in thousands of an inch, like this .020" oversize piston or in quarters of a millimeter, like this 0.50 mm oversize piston. Then, just to make it interesting, there can also be a code stamped in the piston top. This code number tells what oversize the piston is and what type of rings are used. I always measure the old piston so I can order the right oversize.
It seems all the rage now to have sleeveless plated cylinders. Sometimes, it's called Chrome Plating, Nikasil, Electrofusion, Boron Composite, SCEM Composite, Ceramic Composite, or who knows what. These cylinders are bored to the right size and then plated. The pistons use a softer metal than the plating for the rings. The idea being the rings will wear and the cylinder will not. It's been my observation that this is not always true. I've seen what sure looked like wear to me, in more than one plated cylinder. Granted, it's not quite as bad as a steel cylinder but... ! If a plated cylinder is damaged, you will need to bore it out big and press a new steel liner into it. Then bore the new sleeve to the right size for a new piston.
If the damage is not too bad, you may be able to have the damaged cylinder replated. I think this is just a high tech way of doing things on the cheap. One thing to remember. On Chrome Plated cylinders you MUST use cast iron rings and NOT chrome rings. If you use chrome rings on a Chrome Plated cylinder, things do not wear so well. It will start pealing the chrome off. You can use chrome rings on Nikasil, Electrofusion, Boron Composite and some others. Check with the ring's manufacturer to be sure. I gotta admit, plating does work good if you never seize an engine up, and we would never do that, would we?
Something to remember, if you are working on an old bike and are having trouble finding a piston. As long as the wrist pin diameter is the same and you can bore the cyl to fit it. Almost any piston will work. You might have to cut the piston skirt down or drill big ports in it. You might have to grind the piston head to fit the combustion chamber or grind inside the skirt to make it the right weight, but with some imagination you can make it fit and it will work.
For example, in High School I used to take a Honda 175cc twin cylinder piston and make it work in my CT-90 engine. I would bore the cylinder out because the 175 piston (52mm) was bigger in diameter then the 90cc piston (50mm). It also had a much higher piston crown. I would put the valves in the cylinder head and then lay a piece of carbon paper on it with the carbon toward the piston. I then pressed the top of the piston into the combustion chamber and wiggled it about. The spots on the piston from the carbon paper are the high spots.
I then took a hand file and filed off the carbon marks, moved the carbon paper around, rub the piston again, and file some more. I would mark and file until no marks showed up. I would then file just a bit more. I then assembled the engine with a small piece of clay on the piston. Turn the engine over and then measure the thickness of the clay. That told me how much clearance there was between the piston and the cylinder head. You need about .040" of an inch clearance. My 90 was stroked so I had to cut down the piston skirt too. The wrist pin was the same diameter as the 90 so I was in. Why did I do all this when CT-90 pistons are easy to get? Well, it gave me a measured 13.8 to 1 compression ratio. As long as I could get high octaine gas I could fly! The point is, if you can't find the right piston, lots of times, you can make another one fit.
You will find that some pistons look kind of weird. This is because engine designers are always trying to get a bit more horsepower out of the engine. Check these pistons out.
Wow, I guess there is a bit more to pistons then I first thought.
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