This cylinder salvageable?

[cdntbone303]

Husqvarna 550 cylinder that ate a spark plug bottom electrode. Scoring above and below transfer ports. Is it salvageable if I polish out the ridges of the scoring so the rings bridge over without getting stuck?
At the same time what is the max tolerance for cylinder wall to piston clearance? Is there a rule to calculate based on cylinder diameter?

 

[huskihl]

You could take those spots down so that there weren’t any high spots and it would run alright. It might make a better candidate for porting, as the groove on one transfer goes up quite a ways and some of that would be ground out anyway

 

[huskihl]

Usually.003 - .004” is about max clearance down at the skirt. More on cylinders with cast iron liners, less on smaller saws

 

[cdntbone303]

Usually.003 - .004” is about max clearance down at the skirt. More on cylinders with cast iron liners, less on smaller saws

Thanks Huskihl, I think a have a .004” feeler gauge I can measure with. Heck I think I had .012” on a Husqvarna 562 piston I changed out once

 

[TNsawman]

Aftermarket pistons can be as much as 0.011" smaller than the bore at the skirt, otherwise .003-.004" for OEM like huskihl said.

 

[huskyespañol]

Arañazo por encima del puerto de transferencia pierde compresión

 

[smokey7]

Knock the high spots down and run it with new piston and rings. Use a ring slid up in the bore with a piston to keep it square to the so you can check for it catching on stuff we can't see.

 

[cdntbone303]

Aftermarket pistons can be as much as 0.011" smaller than the bore at the skirt, otherwise .003-.004" for OEM like huskihl said.

Like a used oem piston what is the tolerance before having to change it?

 

[cdntbone303]

Knock the high spots down and run it with new piston and rings. Use a ring slid up in the bore with a piston to keep it square to the so you can check for it catching on stuff we can't see.

Thanks will do

 

[cdntbone303]

Usually.003 - .004” is about max clearance down at the skirt. More on cylinders with cast iron liners, less on smaller saws

That on a new piston? What about a used OEM? How much is too much slop?

 

[huskihl]

That on a new piston? What about a used OEM? How much is too much slop?

.0015 - .003 is pretty common new. I’d think .008” is getting worn. I don’t remember the readings on an older used one. But if I could see the intake skirt getting thin I replace the piston