I have a 1990 XT600E with about 33K miles on it. It runs like a champ and pulls hard, so far it's been a great commuter from the east bay to San Francisco. I know these bikes are rather noisy but mine makes some odd sounds (more recently).

When I'm around 3,500-4,000rpm and add throttle I can hear what sounds like a gentle chittering from the valves that turns into more of a valve clatter (not overly loud though) as the RPM's raise. It sounds like tappet noise but it really only does it in 3-5th gear on the freeway when the engine is under more load. The valve train is also quite loud if I accelerate hard from 75-95mph (especially if it's uphill and in 5th). It doesn't sound like it's coming from the bottom end and at idle it's nice and quiet.

Is it possibly a bad cam chain? There are about 9 notches left on the tensioner. Also, if it was loose I would think there would be some aluminum from the cam chain tunnel but the oil is spotless aside from being dirty.

I set the valves last month with the engine at TDC on the compression stroke but I'll be checking them again tonight. Other then the loud valve train the bike has been great, it smokes a lot on startup now but I'm pretty sure the oil is overfilled and the check valve is probably bad (no visible oil in the tank after sitting a few hours).


I've lurked here for a long time reading up on stuff, this a great site for XT info .

Are you running the 85 or 87 octane gas? If so, fill it up once with 90 or 91 and see if the noise goes away. It could be detonation from bad or cheap fuel. That's one possibility.

I always fill up with 91, so I don't think it's that. It sounds more mechanical then detonation but who knows. If I could only get the darn spark plug out...

Why problem getting spark plug out??

Its a really tight fit between the top of the head and the frame neck. I unfortunately don't have any combination of socket/extension and ratchets that has enough clearance to get it loose. If I have time this weekend I need to find some kind of a 90 degree extension and a thin walled socket that will work.

Never had that problem, you put socket down and then the ratchetl on this and loosen it, remove the ratchet and turn ocket around till its loose.

They do have a noisy top end. Even my almost new 600E sounded chatterey.

As long as your valves are adjusted and in good nick and your chain is tensioned correctly, it's probably nothing.

__________________
Did some trips.
Rode some bikes.
Fix them for a living.
Can't say anymore.

Okay, thanks for the responses everyone.

When I checked the valves this weekend, all of the valve clearances were good except for one intake which was too loose. I reset the cam chain adjuster as well and cleaned it out. I finally bought a socket and extension that fit and was able to replace the plug, it didn't look that bad actually. I was a little worried but it just looked a tad rich. The bike definitely seems much happier with the new plug though.

The rpm specific chittering has mostly gone away so it was probably a combination of things. The giant plumes of oil smoke when starting in the morning and leaving work are still a bummer though.

Had the same problem, with clearance getting the sparkplug out. I bought one of those cheap tube metal sockets, cut it , so just an inch stuck out over the head, squished that end flat. Now a small crescent wrench will turn the socket with plenty of room to spare. Mike