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does anybodys 450X make a knocking or slapping sound at idle, mine has since they fired it up at the dealership when i bought it new. it goes away as soon as you give it gas. I figured it was just the high compression engine is a little noisey, but the fact that it has no factorry warranty scares me. I have put a couple hundred miles on it and the valves are within tolerances

These things all sound like a thrashing machine. If you put an aluminum skid pan on, it get worse. Not to worry. Ride it like you stole it.

Joe

my 450's do the same thing at idle

Try increasing your idle by a hair. My (250X) ran a little on the slow side causing the decompression to engage slightly. It sounded like a little man was inside the engine with a hammer... trying to get out.
Halen.

I sure appreciate the feedback I'll sleep a little easier now. can't wait for the snow to be gone , Thank you