Piston ring / piston condition

[dingy]

I have a 1988 with 28,500 miles on it stripped down.

 

Cylinder heads and valves looked normal.

 

Pistons 1 & 2 have a tight oil ring.

 

There is burnt oil below rings on #'s 1 & 2.

 

End clearance on #1 ring about .020" on on all 4.

 

End clearance on #2 ring about .020" on 3 & 4.

 

End clearance on #2 ring about .026" on 1 & 2.

 

Side clearance on all oil rings in tolerance.

 

Cylinder walls good on 2,3 & 4, cross hatching still very visible.

 

Cylinder wall on #1 not bad condition but cross hatching not as visible.

 

No ridge at top of cylinder.

 

What if any thing specific would cause left side pistons to be in worse shape than right side.

 

Picture shows pistons 1 -4, left to right.

 

Gary

[SilvrT]

Just a wild guess but carbs out of balance might ... 1 & 2 running richer/leaner and/or hotter ... causing compression rings to fail sooner maybe????

 

like I said... just a wild guess.

[MiCarl]

Gary,

 

Remember I stated that I had it running on 2 cylinders? I'd thought it was both rears but I could be wrong, I didn't really look into it.

 

What if the right cylinders were the ones that were firing and they got hot enough to cook off discoloration from sitting? Alternatively maybe the left ones were firing and got hot enough to cook on crap from the old oil that was in there?

[gscbertrand]

I'll guess carbs and or air supply.

[dingy]

Just a wild guess but carbs out of balance might ... 1 & 2 running richer/leaner and/or hotter ... causing compression rings to fail sooner maybe????

 

like I said... just a wild guess.

 

I never had bike running.

 

It was MiCarls organ donor parts bike.

 

I think he only had it running briefly.

 

Only real problem outside of this I have found at this point is a couple of the carb diaphragms had a lot of pinholes around outside edge.

 

Gary

[Squeeze]

For me this looks like running a bit rich on 1 & 2 plus Oil Rings stuck on those both. Probably from babying the Motor a little too much.

 

I'd replace the #2 Rings on the left Side and hone #1 Cylinder a little bit. Then ride the Heck out of it...

 

Google for Motoman Break-In Procedure, read his Story and use 2/3 of what he's suggesting.