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Need info. on piston replacement

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010' CRF250. First replacement after 50 hours. Runs real strong but it's time for some maintanance. What piston should I use, a, b or c ? or does it really matter. In the past, I installed whatever I got at the dealer and never considered a,b, or c. But when I ordered it this time, they asked which one I needed. Does it matter? Let me know. Thanks

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My Honda 2 smokers were stamped with a letter on it to let you know what piston to get. I havent seen it on my 4 strokes??

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Typicaly the A, B and C pistons are like .01-.005mm difference in size. Like 77.95, 77.96 and 77.97 for A, B, C. It allows a better match to the specific cylinder. I did not think the OEM Honda had A, B and C designations, there is only one part number. We have several new oem take out pistons at our shop I will look and see if there are designations.

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Your supplier must be going aftermarket, OEM fiche only lists one piston part number. If it were me this the one I wold use. Piston, pin, rings and snap rings $106.20 from Service Honda.

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The old 2 strokes you could buy 3 different size OEM pistons if the cylinder was overbored. I've never seen them offered on the newer 4 strokes so I'm out on this one.

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010' CRF250. First replacement after 50 hours. Runs real strong but it's time for some maintanance. What piston should I use, a, b or c ? or does it really matter. In the past, I installed whatever I got at the dealer and never considered a,b, or c. But when I ordered it this time, they asked which one I needed. Does it matter? Let me know. Thanks

The piston a,b,c or d refers to the size (diameter of the piston). I'm a hobby rider and don't rev the nuts out of my bike and always stick to the standard factory size (a).

Example

A = 77.89 mm

B = 77.90 mm

C = 77.91 mm

If you are going to install a bigger piston +0.01 you might also have to get some work done on the cilinder and I believe it has a special coating so the honing job should be done by a proffesional (cant do it yourself).

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