What size over rings for 250 trailboss

[guitarzan]

Hello fellow members,

I recently tore down my grandsons 1995 250 Polaris Trail Boss to replace the rings. Problem is, its been bored over and now mics at 72.60 at the top, and 72.54 at the bottom. I only honed the cylinder to remove the glaze.

What size over piston and rings do you think I should use?

[LT80]

Whats the top of the piston say?

The fiche shows: .25mm, .5mm, and 1.0mm over pistons.

[Polaris_Rider]

I agree with LT80 it should be stamped on the top of the piston.

That being said, I believe you have a #50 .50mm (.020") over piston since the original bore size was 72mm. It would be a good idea to check the new piston diameter against the bore dims. The service limit is .006" or .1524mm maximum.

Happy wrenching!

[LT80]

On a side note, Ive never been a rings only guy. I figure the walls are wore too so I bore/new piston/rings.

[Polaris_Rider]

On a side note, Ive never been a rings only guy. I figure the walls are wore too so I bore/new piston/rings.

Yessir! And if the bore is out of round or not straight it would be best to bore it anyway, makes sense if you plan on getting some riding time out of it.

Although, I've had times when I was stretchin' a dollar just to ride and I cleaned up my piston and threw in a new set of rings with a hone job. Desperate measures ya know?

Sometimes you can get away with taking the cheaper way out. Other times it ends up costing you 3 times as much as doing it right in the first place!

Wrench on brothers!