These are for a 66E ('98 GP800).

Thanks,

Dave

Because of production variations, Yamaha has different sizes of pistons (thousands of an inch difference, don't ask me the exact number), so the piston perfectly matches the bore, if you change a piston, be sure you use the correct size.
11

piston and cylinder correlations can be found in the shop manual.. as mentioned pistons are slightly different diameters to match with a specifically stamped cylinder. Someone may have their manual handy and could post that reference if your without one.

Thanks fellas. I'll check the numbers on the cylinders & relay that to the parts house.

Dave