power in low end, barely runs after warm up

[tone2crazy]

I'd like to disagree with that, T...

Now that we have a scratch to consider, we need to figger how it got there.
Could be from build-up of combustion chamber debris, (carbon fouling), a broken ring, chunk of a piston, chunk coming in through the intake, or internal engine parts from a casting flaw.

Many years back I lost a cable end from the carb slide and it buggered up the piston crown and cylinder head. Could have just as easily lodged in a place to score the cylinder wall.

...So tell us more about this scratch!
Is it there now? or was it there when the last rebuild was done ?

Do you run an air cleaner???

Best
rc

yeah the weirdest thing can sieze a motor. i once ha the screw holding the butterfly(gp460) on come off and destroy the top end
and i believe he said the scratch was there when he replaced the piston/ring.

 

[rumpnuts]

there was a broken ring which i replaced the piston and rings, the scratch wasnt that bad. wasnt all the way up the cylinder. only about 1.5 inch long. I used the stock air cleaner on the carb.

 

[tone2crazy]

there was a broken ring which i replaced the piston and rings, the scratch wasnt that bad. wasnt all the way up the cylinder. only about 1.5 inch long. I used the stock air cleaner on the carb.

thats a pretty big scratch. i would take off the jug and see if its worse.

 

[back2theborstal]

yeah cylinders dont handle scoring very well. you may be loosing compression from it and or the rings are catching on it. you may even have another broken ring if you took it apart and looked... the symptoms at firsted sounded to me like a head gasket. but now that the scoring was brought up im sure that is it and you are loosing compression from it. new jug, rings, and maybe a new piston sound to be in order..