Weird sound after running at high RPMs

Posted by freppa on
URL: http://vintage-and-classic-hondas.81.s1.nabble.com/Weird-sound-after-running-at-high-RPMs-tp4040349.html

Hi!
My first post here on the forums. Hope i posted in the right place.

I have a honda CB750k 1981 (might be 1981) and after driving the bike at higher RPMs for a while i get a weird, soft but noticable rattling sound from the engine. The sound follows the RPMs so when i revv the engine it speeds up similarly. I'm pretty sure it's coming from the starter clutch down by the left crank case cover. It only appears after driving a good while at the higher RPMs, say 5000 rpms steadily for about 10 minutes. And once it has appeared  the sound stays (now even at lower RPMs) until i turn off the engine and let it cool. Once cool the sounds gone until i go for a run on the motorway again.

I recently rebuilt my starter clutch with new springs and rollers and my first guess was that one or more of three bolts that attach to the what i think is called "the freewheel" had gone loose, but this wasn't case.

Has anyone experienced this before?