Any advice? Dropping a cylinder at 7,000 RPM

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Jonny
Posts: 1
Joined: Wed Oct 13, 2004 12:33 pm
Location: Plattsburgh, NY, USA

Any advice? Dropping a cylinder at 7,000 RPM

Post by Jonny »

Don't ask how but I bent the exhaust valves on the rear cylinder about a month ago. Stripped it down, had new valves installed, and then I put it all back together (new gaskets and all). Fired it up and it purrs like a kitten (more like a lion with the Two Bros pipes).

Took if for a spin and it felt really strong. After getting some miles on it at various RPM's and speeds I finally opened her up and low and behold the damn thing drops a cylinder right at 7,000 RPM. When the RPM's drop back below 7 grand it's back to both cylinders. WTF?

I'm guessing it's either losing spark or a vacuum problem. Anyone heard of something like this? I can go back and retrace everything but if someone has an idea of where to start I would appreciate it. Thanks.
daz1000
Posts: 2
Joined: Mon Oct 18, 2004 11:09 am

Post by daz1000 »

Double check valve clearance may be to tight and closing up
as valve heats up at sustained high rpm.
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