Ms260 pro rebuild or leave it?

[SteveSr]

Do a crankcase vacuum and pressure test BEFORE you remove the cylinder. That way you won't have to do it twice. These have been known to have seal issues on the flywheel side. The other thing that will roach saws is running too lean under load. This could be carb tuning or carb fuel system internals. Which carb model do you have on this saw?

 

[Tinman204]

That's one thing I don't know. It has the H adjustment for sure.

The saw 4 strokes nicely out of the cut and cleans up in the cut the way its tuned now but it's a bit boggy at times in the cut. I attribute that to the piston damage which to me would rob power.

That reminds me, when I first got this saw running it was lean on the high end, I gave the H screw about 1/4 turn which fattened it up.

It was definitely lean when I got it now that I think of it.

 

[Deleted member 117362]

That's one thing I don't know. It has the H adjustment for sure.

The saw 4 strokes nicely out of the cut and cleans up in the cut the way its tuned now but it's a bit boggy at times in the cut. I attribute that to the piston damage which to me would rob power.

That reminds me, when I first got this saw running it was lean on the high end, I gave the H screw about 1/4 turn which fattened it up.

It was definitely lean when I got it now that I think of it.

If you keep running saw with that piston. Order a new cylinder also.

 

[boltonranger]

That's a brand new never used chain.

Oh I see now. I was getting fooled by the floor behind the bar and chain.

 

[Tinman204]

Well I took my saw to a local chainsaw collector and guru this morning. He had all the parts I could need so he said to come over and bring my saw.

Turned out my saw was run to lean. Once we pulled the jug you could see the signs of a lean saw.

Traced it back to a bad diaphragm in the carb. Bottom end seals checked out good. Impulse line and carb boot were also good. He said my saw is almost like brand new but he said who ever used it before me was hard on it fir sure. Dull chain and bad tuning.

The cylinder was darn near perfect so it's good I didn't run it long in it's old state.

We got the aluminum out if the cylinder and honed it just a bit.

It cleaned up to be as new.

Installed a Hutzl piston, rings, stihl carb kit, base gasket and a few other small parts.

Had it all back together in a couple hours and then we cut some wood.

Wow that saw has power now compared to before, it's completely different.

That's to everyone for help.