Running Rough

[modlife]

I've noticed increased vibration and a higher-pitched cyclic top-end noise the last couple weeks. My first thought was a broken ring, but testing compression it seems that both cylinders are fine. Next move was to change the oil - it seemed to help slightly for a couple days but now I'm noticing the same problem and when I checked my oil today I noticed just a small amount of gas in it - not enough to light on fire, so I think the oil is still ok and not the cause. Checked carbs - floats not stuck, no excessive gas. Before I tear into it, how common is it to have a camshaft come loose or something like that? I also noticed today a little "clunk" when I get on the throttle abruptly - sound from bottom end so that leaves out the rear-cush. Ignition coil or main bearing maybe the cause of noise and poor running? The bike seems to actually perform fine...

Thanks for your ideas

-Josh

[ohgood]

I've noticed increased vibration and a higher-pitched cyclic top-end noise the last couple weeks. My first thought was a broken ring, but testing compression it seems that both cylinders are fine. Next move was to change the oil - it seemed to help slightly for a couple days but now I'm noticing the same problem and when I checked my oil today I noticed just a small amount of gas in it - not enough to light on fire, so I think the oil is still ok and not the cause. Checked carbs - floats not stuck, no excessive gas. Before I tear into it, how common is it to have a camshaft come loose or something like that? I also noticed today a little "clunk" when I get on the throttle abruptly - sound from bottom end so that leaves out the rear-cush. Ignition coil or main bearing maybe the cause of noise and poor running? The bike seems to actually perform fine...

Thanks for your ideas

-Josh

If mine stops making valve train noise, cam end-play racket and chain whine, it must be out of gas !

Seriously, the clunk could be your chain out of adjustment, or the drive sprocket getting sloppy on the splines. The top end noise sounds like either cam end play or valves in need of ajustment.

Just my guesses.

[wera90ex]

I've noticed increased vibration and a higher-pitched cyclic top-end noise the last couple weeks. My first thought was a broken ring, but testing compression it seems that both cylinders are fine. Next move was to change the oil - it seemed to help slightly for a couple days but now I'm noticing the same problem and when I checked my oil today I noticed just a small amount of gas in it - not enough to light on fire, so I think the oil is still ok and not the cause. Checked carbs - floats not stuck, no excessive gas. Before I tear into it, how common is it to have a camshaft come loose or something like that? I also noticed today a little "clunk" when I get on the throttle abruptly - sound from bottom end so that leaves out the rear-cush. Ignition coil or main bearing maybe the cause of noise and poor running? The bike seems to actually perform fine...

Thanks for your ideas

Usually when I hear that sound ,just on throttle up, I'm looking at a big end rod bearing that doesn't have enough oil pressure or too much clearance. Also, on the GS twins, I've seen where the clutch cover was replaced and gasket material got into the oil passage that leads to the balancer bearing. The debris caused the oil jet under the  bearing to clog and take out the brg and the balancer. I'd certainly do an oil change and check for sparkly oil. Good Luck

Rich Graver wera90ex@aol.com

[modlife]

I should have noted that I recognize what the camshaft and valves sound like...this is almost more contained in the cylinder. I did lay the bike down after the oil change so maybe clogging is the culprit...didn't really think about it since the bike was upright before it even stalled out, and it was a few days after that it started with the noise. I actually even replaced the Emblem plate before the noise started...

Also, it has new sprockets and chain so that shouldn't be an issue. By cyclic I mean the noise is dead on with the piston movement - not the faster "cam chain" sound either. Started it this morning and it sounds confined to the right side so I'm thinking maybe main bearing on the "clunk" and lubrication issues up top causing the cyclic noise. I'll do another oil change right now and let you guys know if it seems to solve anything.

The vibration seems worse now too, so maybe I'll check the camshafts...

I really need this thing running well before Thursday because I'm trading a girl my daily '93 GS for a '99 GSXR 600 that she can't handle... the GSXR has crazy miles on it (65k) from her brother, but damn is it a nice bike...

[sledge]

Always difficult to diagnose faults by reading a description of the sound its generating but........I once had something very similar to what you describe with a Honda 400 superdream, two of the 3 had springs in the balancer-shaft drivegear had failed and the gear had become loose and was rattling around on the shaft. It caused all sorts of strange and very noticable noises and increased vibration. Its a longshot but given the GS5 uses a similar setup I think its worth pulling the cover off and having a look at the drivegear and the springs.

[modlife]

Figured it out...

melted foam on the valves...after taking the airbox off I noticed some left over foam from a rotted air filter...never thought that the previous owner would have let something like that go. Vibration fixed, but need some new shims now...

[beRto]

I'm a little confused; how did melted foam get onto the valves? A picture would be great!

[modlife]

I'm a little confused; how did melted foam get onto the valves? A picture would be great!

i should have thought to grab a camera...

Apparently some of an old foam air filter that was in the airbox got sucked up - never thought someone would leave something like that in the airbox. It was literally 1/2 of a foam filter that had dry rotted or something and crumbled off.

NOTE TO SELF: STICK TO K&N

Looks like I'm trading the GS for a Gixxer

[ohgood]

Sooo, the foam was stuck to a valve ?  Crazy man, never would have guessed that.

Now you're back to all the 'regular' noises gs's make, right ?

COol