My Bike, 2003 Bonnie T100, 2k miles.
My exhaust valves were smashed! Rods bent. My mechanic could not figure out why. All parts were still in good shape, chain tentioner, cams, drives, chain etc. Still had a bad, timing problem. Any ideas what could have happened?
JG
I want to verify terminology here.
the valve heads and STEMS were bent?
when you say rods, it means connecting rods.
if you bent a connecting rod, the piston dome should be impacted and the mains/rod bearings/wrist pin bearings are suspect. any bad bearing (eggshaped/dimpled) will throw the travel spec out. you might be into some money here.
this engine sounds beat to me...maybe the head shaved?...domed pistons?...loose valve seat in the head? POSSIBLE: hung up stem in the guide can stick a valve open for impact when everything else looks right.
...and I'm not at all clear on your timing remark.
a bent valve will show as horrible compression that might be confused with timing.
your first move is to check for numbnuts parts installed...used bike?
next move is check someone didn't fudge the cam on bad advice. a high lift cam lobe can do that...and coupled to a tooth move?
then double check the deck height for a skinny head or base gasket.
valves can warp when cooled too quick...which is why dragsters put balls in the exhaust on a hot engine...and exhaust systems are so long...but my first guess here is some numbnuts did some engine work and doesn't know engines.
find someone who knows engines...not every shingle hung out there is valid.
I'd be glad to look at that for you and tell you exactly where the chicken sh*t in the buckwheat.
first clarify the situation on the bike ownership record, then we'll zero in on blame.
best guess
1. valve hung up in the open position
2. someone "hamfisted" was playing expert with cam timing or clearances.
I don't think revs are the culprit...heat and oil pressure may be.
edit: if there was a previous scramble and they didn't get the oil passages and pump pick-up screen clear, it can run a bit until the heat seizes a stem or whatever...this is what it sounds like.
can I see some pictures?
specifically of the valve stems where they run in the guides.