Valve Noise? 1990 XT600E
 

I just adjusted the valves on my bike, checked adjusted and triple checked before putting the valve covers back on. Now the valves make a wee bit of noise, as in, when standing near the front of the bike, you can hear the valves rustling. Even more so when you get right down close to the engine.

Is it supposed to make noise? Or am I going to have to yard-sale my bike again and adjust the valves.

noise before
 

Hi Micah,

was the noise there before you set the valves? Normally valves get more silent because the clearance is getting less. If there was some noise before setting them. I could be also the piston. If the noise just came after setting the valves, you did something wrong.

regards

Thomas

Have you adjusted the valves at TDC on the wrong engine revolution (i.e. between 2nd and 3rd stroke instead of between 1st and 4th or vice versa)? I cant speak for your bike, but on my old XT I have to crank the engine over to the TDC mark twice to see which has the most valve clearance gap and adjust from there. Dont ask me why this has an effect on the cam, it just does and so I do, otherwise when I crank the engine another revolution the gaps are wildly out.

Yeah, when I was cranking it out, I waited for the mark to pass when the exhaust valves were open. Then rotated it again till there was no valve action when the mark was in sight.

I adjusted the valves again, and two of them were *maybe* .001" out. I could barley jam the next feeler gauge up into the gap.

Valve Noise
 

Hi Micah,

I've been working on a similar problem. My '90 XT600E has 14700mi; just got it. Bought it with some noise but got it cheap. I've listened to a couple other 1990's with 10-12Kmi and the valve train has light mechanical whirl that the mechanic says is usual. Mine got noticably quieter after adjustment and correct weight oil. However, I've got the occaisional lower pitch knock on start up that you mentioned in your Oct 2007 post. Did you figure that one out? Is it gone now?

Thanks,

Jeff

No, it really only happened a couple of times - back in October. Since then I've put maybe 3000 miles on it and it hasn't done it since.

There is one noise that keeps confusing me. It's a top end "squeak", or a whistle or rattle-like noise. It's hard to describe. It seems to happen only at a certain RPM, around 50-55mph in 5th gear. I've adjusted the valves, and changed the oil and it's still there. Anyone have any idea what that could be?

Dont laugh too hard but...
That sounds like it could be sympathetic resonance. Singles are prone to it as they age. I have a 100cc gasser in a model airoplane that at about 3500rpm causes the entire airframe to shake like a rattle. A bit above or below and all is well. At about 2800 rpm on my 3AJ the fairing vibrates briefly and makes a hell of a racket. No amount of checking that all the bolts are tight etc makes one jot of difference. It drives me bloomin nuts!! It's like having a squeak in a new car.

I was thinking about this again. If it is a squeak like a deflating balloon.........carb intake system leakage/blockage on the manifold or airbox?

I'm dead curious now. Let us know if you resolve the problem what it was.

Yeah, it's been bugging me for the past ~4000 miles. I'm going to pull the headpipe off this weekend and see if it's sealing properly, and put on a fresh coat of paint while I'm at it.

When I got the bike I replaced the intake rubbers on the front-side of the carb, and I have some spares for the back-side, maybe I'll go in and put those on too.

It's just such a huge PITA to get those carbs out...

I pulled off the pipe this weekend. I repainted it high-heat black, and sealed all the connections with "Muffler and Tailpipe Sealant". This morning's commute suggests so far, so good.

I really need to take it out and get the engine good and hot before I'll really know if it's gone or not, but right now I'm going to say that it was an exhaust leak around the headpipe seal.

Hmmmm.....
 

I just rode it 800 miles last weekend, and the noise is still there.

I got down real close to the engine and played with the throttle. There is a slight knock, like as from the piston, that seems to develop into the squeak at high RPM, hence the reason the noise at highway speeds. Could it be a loose piston pin/something else that causes a harmonic ring when the engine is ran at higher RPM?