I'm rebuilding a 99 xplorer 400. I pulled the top end. Found a little scoring on the piston. I would like to have it oversized. On the top of piston it is marked 38B. I know that the stock is a 38A piston. What does 38"B" mean? Thanks

 

According to the manual the 38B is the standard piston and fits the EC38PLE-06, 07, 08, 09 these numbers are not 2006, 2007, 2008, 2009

The 38A fits the EC38PLE-04, 05

I wouldn't use a Polaris piston anyway. Go with a wiseco piston. They will last a lot longer and don't have the famous catastrophic piston skirt breakage like the Polaris pistons.

 

Thanks, do you have experience with the 99 xplorers? I'm try to figure where the water is coming from on mine. Milky white oil coming from the counterbalancer breather/vent line. I'm hoping it's not coming from the water pump seal. I have the top end off now and am replacing the head and lower gaskets.

 

Probably the water pump seal like you said.

 

X2