Folks, this problem is driving me nuts. I can put the bike on the stand and wind it up to redline, no problem, I can put it on the side stand and wind it up, no problem. I can wind it up going down the road, no problem. The problem I have is when I am in 5th gear at about 3200 RPM, I get this god awful engine rattle that I can feel in my feet and hear. The engine is timed perfectly, it runs strong, the valves are adjusted, the cam chain has the right tension, the plugs are burning evenly with my PAMCO ignition. If I open the throttle or let off the throttle, the noise goes away, as soon as I get to either side of 3200. I have been driving this bike like this for some time and I just can't go 45 miles an hour in 5th gear (3200 RPM). I have tried putting my foot on both of the stands while driving to see if they are rattling but they aren't. I don't know what part has the resonant frequency of 3200 in 5th. It seems like its happening because maybe the engine is being lugged down at that low speed in 5th gear but I can't figure out how to change that. Any ideas?
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jd750ace
Front Toward Enemy
Check your front sprocket and make sure it's tight, and serviceable. Worn teeth can make the chain oscillate heavily at certain speeds. 3200 RPM is not "lugging" this engine, I don't care what's said. Mine pulls clean and smooth from around 1800 rpm. No lurching, no chugging, no chatter.
3200 rpm is in the wierdness zone, where piston inertia dynamics match combustion forces. But before going there, this is also the zone where camchains can rattle if the front guide is damaged.
First steps would be to pull both filters and look for debris from the chain guide. If you find black plastic and aluminum chips/powder, the guide is likely the culprit...
First steps would be to pull both filters and look for debris from the chain guide. If you find black plastic and aluminum chips/powder, the guide is likely the culprit...
Previous post double posted - wierdness...
XSNate
XS650 Addict
I had a similar sound that drove me nuts right at 3100rpm. I was afraid it was a main bearing? Turned out that my right side exhaust was loose by the footpeg. It made the bike feel like it was breaking right at 3100. Hope this helps
