My bike's been doing this since I got it, but lately it's gotten a little worse.

On top of it, just last week it started making a new noise that sounds like it's kind of coming from the front of the engine.

When riding along and holding speed, the bike will kind of lose power for maybe 1/4 of a second - the RPMs don't go down, no loss of speed, you just kind of feel it. When I first got the bike, I just thought maybe it was from gusts of wind, but now I'm pretty sure it's the bike.

This seems to happen under 6000RPM (I'm not sure I'd feel it above that?), and I know it's not a fuel starvation issue - I replaced my fuel lines with bigger lines right after I got the bike.


The new noise kind of sounds like metal just barely touching something - it's mostly noticeable at low RPMs (idle), and seems to go away at higher RPMs.

My theory is that perhaps both of these are due to valves needing adjustment.

Any thoughts?

PS: I really wish there was someone in Miami to help with this stuff.

Need more info like miles.  But it sounds like it may just need a tune up

Not sure about the momentary loss of power yet (spark plug "missing"?) but the new noise could be (harmless) "camshaft endplay".  You can find lots of posts about it by searching, but...

...it's basically where a camshaft moves slightly from side to side (along its length) when there's little vertical tension on it from the camchain (at idle).  When you rev up, the chain pulls harder and kind of clamps it into place, reducing the sideplay.

Sorry, I should have posted a bit more info:

2004 Model
9500 Miles
Converted to Synthetic about 4000 miles ago (time for an oil change) and put new spark plugs in at the time.


I thought it could possibly be "camshaft endplay" but shouldn't that happen gradually? Or is it known to just happen out of nowhere?

BTW, I'm right in the middle of studying your Valve Adjustment video Kerry, and as soon as I'm done I'm going to go out and buy the stuff I need.

I'm not sure I'll finish the project today (I don't really have anywhere locally I can get shims from I think) but I'm at least going to get in there and poke around.

Same bike as mine. You probably need a full tone up including a carb rebuld. Around 500 clams

I did a carb rebuild myself a couple thou miles ago because it was leaking into the airbox. I didn't find anything wrong but the leak stopped after I put everything back together.
(See thread with video here: http://gstwins.com/gsboard/index.php?topic=33086.0)

Do you still think that'd be necessary?

Could be I worked at suzuki so I was heavy on maintenance. If you want PM me and I will give you my phone number

Quote from: Raydr on January 12, 2008, 09:18:11 AMI thought it could possibly be "camshaft endplay" but shouldn't that happen gradually? Or is it known to just happen out of nowhere?

It sounds like it is happening gradually.  Right now it sounds "like metal just barely touching something", but later on it will probably sound more "clunk"-y.

Okay, I'm playing with the valves and made a bad discovery:

I have zero clearance on all four. At first I thought I was doing it wrong, but unless I'm missing something, I absolutely have zero clearance.

How could this happen, and what do I do?

Oops, I WAS doing it wrong. For some reason I thought I was supposed to check for .5mm, not .05mm.

So, my right exhaust seems a little tightl, and my right intake will accept a .12mm shim.

I'm going to try swapping the shims in them...

Nice work!

I guess I should have asked about the frequency of your "new sound".  If it's a quick "tap tap tap tap tap" then yeah - it could be your loose valve.  Camshaft endplay is more random; it's "choosy" about which revolutions of the engine it will make noise on.

I was going to say oil level, especially since synthetic is thinner and is more likely to get past the valve seals and rings and get burned up.

Valve adjustment would have been the second guess, with a question about the mileage of the bike and when the last valve adjustment was done.