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Piston A, B, or C?

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Calling the local dealer was more than a headache as he had me looking over my cylinder for something indicating which piston he should order. He then told me that there was a note that said "This cylinder is measure only" and that the only way to know what piston to choose was to measure.

Its a 40 minute drive to his shop just to get it measured, then back again in a few days when the parts come in.

To make it more confusing, motosport's weisco kit just has two options: standard or .80 over.

Edit: The rep at motosport explained to me that the weisco only needs one size because the piston expands to fill the .003-.003 gap as the bike warms up. I'll just go with the wiesco kit.

Edited by AAJAKE

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I always through it was A, B, C, and D or maybe im wrong. Also i read somewhere in the forum that any would work... but that was a year ago so i could be wrong

.... i am to lazy to think i just want to ride lol

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Edit: The rep at motosport explained to me that the weisco only needs one size because the piston expands to fill the .003-.003 gap as the bike warms up. I'll just go with the wiesco kit.

🤣:lame:

not quite...

Either way you could have gone with a C or D, the difference is under 1/2 thousands (.0004") between each size

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You really have to measure the cylinder with a bore gauge to select the right size piston. The stamped a b c letter on the cylinder was the measurement when the cylinder was new, one or two rebuilds later and your cylinder is worn past that stamped size.

If you guess too tight it will have a 4 corner seizure when warming up, guess too loose and the piston skirt will slap the plating and will damage your cylinder. To save u money in the long run take the cylinder to your local machine shop to be measured for wear and taper. The last 4 rebuilds I did at work were from guessing piston size and were all expensive, and could have been avoided. Just hate to see another person lose $$$

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