Weird sounds!

[anticoriolis]

Hey guys,
I've got a pronounced, intermittent, RPM-tied squeak coming from my motor. It's loud-ish (I can hear it at 20-40mph) and is definitely engine related, because I can't get it to squeak with the motor off. If I revv it up and hold it at 4k for a second and let off it'll squeak away at idle. Sounds a bit like nails on a chalkboard (or more disturbingly like metal on metal)

The history is I bought the bike 6 months ago (a 2001 GS500[k]) with what was ostensibly a pair of dirty carbs. Ended up being cracked cam caps and a vacuum leak. So I had a local shop (O'Hanlons Motorcycles in SF) do the work, salvaged head valves and cams in the bike, new intake boots and a new drive chain, and when I got it back I changed the oil. Rode it around for a week or two without any problems, valves seem kinda loud but maybe I was just listening too hard.

Any thoughts?

[anticoriolis]

Anyone? Should I park it up until I can get it back to the shop that did the work?

[sledge]

I would........and make sure the first thing they check is oil-pressure

[The Buddha]

Squeak ... you mean ... like a old VW beetle ?
Cool.
Buddha.

[simoniz]

Could be an air leak from a bad engine gasket or a loose spark plug.

[anticoriolis]

Squeak, chirp... high-pitched, short, repetitive metallic sound. I lubed my drive chain, rode it around for a half week and it went away... killed my motor while it was doing it and coasted downhill, motor in neutral and then again with the clutch out... still made the noise. Which makes it sound like it's chassis. But I was only able to get it to do that once with the motor off, and now it's cycling with the motor. Chirp-chirp-chirp-chirp in time with the motor going around. Very intermittent. I took it in to the shop, wasn't doing it at all. This morning it was quietly chirping while it was idling, and every once in a while I'd get a pretty loud one out of the blue, usually under throttle. Gremlins! I don't know how else to explain it! I think all I can do is try to get it round to the shop while it's making the noise? Which means I need to get out and ride at lunch every day!

[pkhoff]

That "chirp" description sounds very much like a rod bearing that has spun. I have heard this in car engines, don't know if a bike would make the same sound, but I'm guessing it would.

If it is a spun bearing, you should progress to a knock or seized engine shortly.

Have you checked your oil for "glitter"?

[anticoriolis]

Yeah, I've been checking the oil every day. No glitter, no shimmery stuff. I'm starting to think it's my front end that's squeaking. Streets in SF are so chopped up it's hard to tell.