I'm helping a friend put together a 686 Raptor, and was curious about the piston clearance and ring end gap. The shop that sold the piston told him to set the bore for .002" clearance. That seams a little on the tight side of what I would recomend, but we did it his way anyway. If Raptor720 reads this, I would love it if he could give me a call at my shop and share his expertise. I know those "dirt-doo's" inside out, but this Raptor stuff seams a little odd.

Thanks

 

it won't fit in the hole with .002 clearence, get a second opinion

 

.002 is what we used on mine as well (J&E 102mm), seemed tight but it is holding up well so far (about 15 hours on the motor) dont have my notes with me at work though

 

Right out of the factory manuel. piston to cyl. 0.05-0.07 mm, top and sec. ring end gap 0.30-0.45 mm, oil ring end gap 0.2-0.7 mm.

 

that is for stock piston and rings, high comp should not be the same, I will check my notes to be sure