Rough noise from gears

[jlamont]

I wonder would somebody be able to shed some light on a problem, or if they have experienced something similar.  Recently I've noticed a rattling noise coming from what I think is the gear box when decelerating in the lower gears.  I think it's the gearbox as when I engage the clutch the noise dissapears.  The bike has done 10,000 miles.

Thanks

John

[scratch]

I think the drive chain is loose. Check your chain slack.

Edit: Oh, yeah, and welcome to the site!

[Kerry]

In my experience drive chain noises don't usually depend on the clutch being engaged, since the chain continues to go around anyway.  But I could be wrong!

Can you describe the "rattle" any better?  Is it a clear metallic sound, or a more muffled noise, or...?  Is it high-pitched (high frequency) or distinct enough that you can almost count the "ticks"?

Can you duplicate the noise with the bike on the centerstand?  (Probably not without a load on the engine, but worth a try.  Just make sure the bike is well-weighted toward the front.  The idea is to move your ear around the engine until you can pinpoint the source of the sound.)

[newbieone]

Just a question but it sounds as if you are downshifting the bike incorrectly.  Make sure you rev the motor up a little when downshifting to match the gears up correctly. Not sure if this is your problem but just some advice.

[scratch]

The reason I mention the chain is first I want to eliminate the simple thing first. When decelerating the top run of chain slackens and may be riding on the chainguide on the swingarm. The engine loses rpms faster than the speed of the rear wheel and so the rear wheel is pulling the chain around the c/s(countershaft) sprocket and slackens the top run. When you pull in the clutch you remove this dragging force and the chain returns to a neutral, no load, ride on the sprockets. And a proper matching of engine speed to actual, or rear wheel speed, as newbieone has pointed out, may help too.

[Kerry]

Good points.  I guess I was thinking of my most recent "chain drive noise", where the chain was too tight.  The state of the clutch didn't matter - it was ALWAYS noisy.

But I can see how a too-loose chain could do just what you describe.  

[jlamont]

Guys, thanks for all your replies.  

In the end it was easily solved.  The bloody chain was too tight.  I'm new to this game and so was relying on my Haynes manual.  It tells you to adjust the chain to the recommended freeplay set up on its center stand.  However what it doesn't tell you is that when you place a 230 pound man on it its going to get a lot tighter.  The local Suzuki dealership said if I can, get someone to sit on the bike for the final freeplay check.

Thankfully I caught it soon enough and didn't damage any of the gearbox bearings.

[MarkusN]

Had the same thing happen to me. However, I wouldn't have called the resulting noise "rattling". It was more of a grinding, churning noise that resulted.

[jlamont]

I think in my case a dull rattle was the closest description but it definitely wasn't healthy.  Another good point the dealer gave me was when applying the freeplay check no force should be applied when pushing the chain.  Lift your finger below the chain and as soon as ANY resistance is felt thats the end of freeplay.

I know this might seem obvious to most, but to beginners like myself these tips are helpful.