Mechanical Noise from under tank/top of rear cylinder
 

I just noticed a noise a couple of days ago. It is sounds like metal hitting metal and it occurs two or three times in a row and then is silent for a few seconds and then does it again. I've only notice it while at idle - I can also actually feel it. The noise appears to be coming from the rear head.

My first thought was CCT, so I've parked it (it is my main mode of transportation). However, when my CCT's were failing before, I don't remember the sound like this and am wondering if it could just be the valves needing adjustment. The bike runs fine.

A little history: It is a 1998 and has 78,000 miles on it. In 2003 at 34,000 miles I had a Honda dealer check the valves and he only adjusted one valve. In early 2008 at 62,000 miles, there was valve train noise and a Honda dealer replaced the CCT's as well as checked the valves (the valves did not need adjustment). That is all I've had done relating to the valves.

This time around I am going to do the work, but I thought I would seek advice from here as to whether there is any way to distinguish a valve needing adjustment noise versus CCT's failing? And any other advice you might have relating to this issue. I've already learned much from the forum on how to replace the CCT's and adjust the valves, I just don't want to spend any more money than I have to.

A couple other things: I am also wondering, if I remove the CCT, will I be able to tell from looking at it that it is going bad?

Also, does the CCT guide ever need to be replaced?

Thanks for any advice!

The only way to get a real answer at this point is to pull the tank and rear valve cover. Then pull the center plug on the flywheel\stator cover.

Then take a socket and turn the engine over by hand and see if you can figure out what is making the sound.

Also check for "witness" marks on the valve cover (or look to see if something was hitting the valve cover anywhere....;))

Other than that it's just guessing by internet noises....

Oh and the guides are only replaced if you replace the chains, so you really don't have to worry about them.

I took the rear head cover off and I didn't see any signs of anything "hitting". I checked all the valve clearances and they are good. I then removed the rear CCT and disassembled it. Nothing looked amiss with it, no gunky stuff, it looked very clean.

Any other thoughts? Would it make sense to replace the CCT even though it looks okay?

Thanks for any advice.

As you have taken it apart, you should replace it. You can either run another stock unit or switch to manuals at this time, the choice is yours.

I just don't recommend reassembling the old one and running it. ;)

CCTs replaced - still have noise
 

So I ended up replacing the CCT's. It turns out that the rear one was going, I just didn't realize how bad it was until I took out the front one which was really tight. So I am glad that I took it apart and replaced them because it looks like it needed to be done. Unfortunately, I got everything back together and it is still making the original noise that started this whole thing.

Upon further investigation, the noise only occurs when in neutral and the clutch lever is released (clutch is engaged) and it is worse when the engine is cold. Now, it would make sense that there would be a little more noise and vibration in this situation, but what's happening is on top of the subtle additional noise and is repeated taps at random intervals - almost like someone is tapping the frame with a wrench: tap.... tap..tap........tap tap..........tap. And I don't mean a light tap, it is pretty significant.

I've never had the clutch apart and the only thing I've ever done related to the clutch is replace the clutch fluid a few times. The bike runs good. No clutch slippage, powers right up to red line just fine.

Any ideas? Thanks.