Jred 625II jug and piston damage

[371groundie]

got the saw for free and was told it runs. upon further investigation i tried to start it and the pull cord wouldnt move. took off the recoil and made sure that was all copasetic. recoil worked as it was supposed to. and i could turn the flywheel both directions. took the jug off and you see what i saw. looks like a chunk of ring. broke loose and lodged in the exhaust port. but the ring is whole and i cant find any foreign objects in the jug or crankcase.

any suggestions? can i just smooth up the rough edges and run it? the only damage on the piston is on the top edge. the ring is whole( and sharp, it made me bleed, now my thumb throbs when i hit the space bar. )
to my underexperienced mind it should run if i clean up the rough spots. what would you do? any ideas what might have caused the damage?

 

[371groundie]

didnt realize the photos were that bad. let me know if you need cleaner ones.

 

[PES+]

Most likely

Someone used a screwdriver as a piston stop to remove the clutch.

 

[Mad Professor]

didnt realize the photos were that bad. let me know if you need cleaner ones.

I thought it was the vodka kicking in.

 

[371groundie]

screwdriver could be the case! when i received the saw the clutch was not tightened onto the crank and the rim sproket was missing. i though it was awfully handy as i had a new rim sproket sitting on the bench.

and ideas if just polishing the rough spots will fix the problem? im specifically worried about the ring passing by the damage in the exhaust port. in essence the damage has raised the exhaust port. not understanding port work at all would the small amount that the damage raised the port totally screw up the way the saw runs? should i just clean up the rough edges or raise the port all the way across its width?

just for perspective ive never done any grinding on any cylider ever. so speak slowly and use small words.

 

[rmh3481]

Hi Groundie,
Your going to need to measure the piston and compare how much will need to be removed to buff out the scuff. The pics are pretty blurry.

About the exhaust port, you do not want a flat port roof. The exhaust port should open in the very center first with a roof that looks like a convex arc. The reason for this shape is to allow the combustion pressure to exit without pushing the ring out into the port. Remember, the ring is partially sealed from the pressure of combustion and will need some cylinder material to support it.

Best wishes,
Bob

 

[371groundie]

good news is that baileys carries a piston for this saw! so that will solve one problem.

thanks for the info on the shape of the port! any idea what effect raising the port mabey a 1/16th inch would do to the saw?

just doing some thinking out loud here:
raising the eshaust port would open the port sooner after combustion. that seems like it would be bad. less burn time and mabey an incomplete burn. am i on the right track?

this was a free saw that im trying to make a runner not a hotrod, hoping to get this fixed up without getting carried away.