Whining/Grindling/Rattle sound from engine!

[Ted]

It started happening on odd occasions, but now its becoming more regular.

The sound isn't easy to describe, its a bit of a tinny hollow grinding rattle sound!

It seems to happen every now and then when I change gear, but mainly when I let off the revs.

One of my mates said it might be piston slack or a loose cam chain?

It also seems to be getting slightly slower, and 5th just makes it loose speed.

Its an '02 Gilera Coguar, 4-stroke 125cc.

What is it most likley to be? If it is the cam chain, can I adjust it?

Cheers. Ed.

[Wafer_Thin_Ham]

I'd go with cam chain too, it could be that your Cam Chain tensioner is sticking.

You should be able to get to the CCT and give it a hand with the tension, but you'd need a manual, or just take the CCT out and clean it and replace, or just get a dealer to whack a new one in.
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[Ted]

Ah... now the problem is Haynes do not make workshop manuals for my bike, nor do any other companies that I've found!

The only manual I have got is the owners manual, which is shite!

I'm told the engine is pretty much identical to a Honda CG125, if that helps!