Topic: Transmission Tapping

[IndyFour]

I know that it's nearly impossible to diagnose a problem without seeing/hearing it for yourself, but maybe you can help me know what to look for.  Here's what's going on...

I have a '74 CB550.  Bike runs great and rides great.  Decided to take it for a longer ride today since it was such a beautiful day.  Rode a total of 80 miles each way to see my family.  Ride was all highway and did about 65mph most of the time.  Upon arrival at my parents house, I noticed a "tapping" coming from somewhere down below.  Up until this instance, I've never experienced this noise before.  After my visit, I head home and try to pinpoint the noise as I'm riding.

The tapping seems to be sounding at the same rate as the the chain is turning, which leads me to believe that maybe the chain is worn or is hitting somewhere, but the sound seems to be coming more from the transmission.  I haven't looked at the front sprocket on the transmission yet, but I can't imagine what on that part would cause this sound.

Regarding the sound, it's most prevalent in the higher gears (3 through 5) when I'm giving it gas....if I let it up and just coast in gear, no taping, but give it torque and the tapping is louder.

Not knowing what the inside of the tranny looks like or contains (never had it opened up), is there another chain inside that turns at about the same rate as the drive chain?  The tapping almost sounds like a chain with a link or part that is coming off and is tapping on the inside of the case or something.

Seeing as the drive chain is pretty old and needs replaced anyway, I'm going to go ahead and do that and also replace the front sprocket....but something tells me neither of these parts is causing the noise....but maybe they are.  I haven't had the drive chain off before and maybe the front sprocket is toast.

Any ideas?

Thanks!

[Hasenkopf]

It's really hard to tell, on a bike, where the problem only happens under load,   switching out the chain and sprockets is probably one way to eliminate them as a suspect.  loose rivets on the clutch drum??   I have a similar problem on my 750,  an am wondering if I should tear into it this winter just to be on the safe side....

[the technological J]

how loose is your chain? I've been amazed at some of the things a loose chain can do.. from thinking the bike was seriously screwed to just a simple clack.....  for just now until u get a new chain tighten this one up and see if the problem continues

[IndyFour]

Just a quick update.  I checked the chain and it was in fact loose.  It really needs to be replaced, but for the time being, I just tightened it and gave it a good oiling.  Between having too much slack and being a bit dry a crusty, this was what was causing the tapping sound.  It's completely gone.  It was only a few hundred miles ago that I last adjusted it...so I was surprised that it was as loose as it was.

Thanks for the help guys.