Huasheng burnt valve(s)?

[unior]

My huasheng recently started popping and backfiring. I adjusted the valves and the problem went away temporarily. Now its starting to pop and backfire again under heavy loads and lower rpms. Could I have burned a valve? Do I have to split the entire motor to get them out?

 

[unior]

found valves for eight bucks i wonder how hard they are to install

 

[unior]

Well I tore her down, removed, cleaned and reinstalled the valves to no avail. The engine makes no power and backfires. She's about done for I worry. I guess the seats are scored or messed up?

BTW HS valve removal = remove clutch, remove flywheel, removed front cover, disconnect connecting rod bolts and push piston up in bore away from crank, remove crank, remove piston, remove valves.

 

[GearNut]

Burnt/ pitted valve seats will cause what you are experiencing as well as severely reduce the compression. Have you done a compression test? I have no idea what the compression should be on your engine but anything less than 100 psi is very low.
Are you positive that the ignition is firing properly/ correctly timed?

 

[unior]

Burnt/ pitted valve seats will cause what you are experiencing as well as severely reduce the compression. Have you done a compression test? I have no idea what the compression should be on your engine but anything less than 100 psi is very low.
Are you positive that the ignition is firing properly/ correctly timed?

I visually inspected the seats but they are tough to see way down in the engine. I dunno maybe ill try lapping them.

 

[Old Bob]

backfiring is usually an ignition timing or misfire problem, as indicate under heavy load or low rpm I would change plug, its common for bad plugs to misfire under load.

 

[unior]

Ok so now my huasheng is out of time. I realized upon removing the crankshaft the cam gear moved outta time. But I can't find any timing marks on this gear.

 

[GearNut]

Well, that's alot easier than repairing a burnt valve seat.
There has to be timing marks on it somewhere.
One tooth shorter width wise on the gear?
A little dot?
A short line?
I have even seen the mark being just a v notch in the tip of a gear tooth.
That was a PITA to figure out.

 

[unior]

found the timing mark on the backside of the plastic cam gear. too bad it's half destroyed...pics to come...