Bob,
There seem to be several things here in question in my mind, as you may be up against more than one problem.
was the cause of the bent valve addressed? A new valve kit was installed.
but what got the valve into the piston in the first place?
"got it running but you can't hit the throttle WFO or past 50% for that matter"
Have you been able to verify the timing to be correct?
" It will idle to hot, then just shuts down?
He thinks it is the carb...but is was fine all summer and never adj. or touched".
This sounds electrical, heating up and opening a circuit.
I think I would test the ignition/electrical equipment, and tear down the engine for some R&R. I'm sure this is not what either of you want to hear, other than systematically verifying everything is working properly you could be throwing lots of dough at the bike with no baseline to work from.
A service manual is probably around $40.00 and a gasket kit, rings and consumables is about $150.00 And that's if there are no other items needed.
( I say rings account I believe the life of a set of rings on an mx bike is about 25hrs.
)
Don't shoot The Messenger!
Tuck\o/
