Hi all, I have an xtz 660 1991. Is it normal for it to backfire and pop on shutting throttle down. Any help is much appreciated, Cheers

Unlike the current fuel injected 660s, the old 5 valve carburettor models shouldn't pop or backfire on the overrun. However, the one I owned back in the late 90s did backfire when I bought it, but that was down to poorly sealing exhaust gaskets at the cylinder head/downpipe joint which allowed air to be drawn into the exhaust on a closed throttle. New gaskets solved this issue.

First thing I'd do is check closely for leaks anywhere in the exhaust system, but particularly close to the cylinder head.

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It looks like there are no gaskets at all at the cylinderhead/downpipe joint. So will have to source some. Thank for the heads up, had already replaced carb o rings just in case, they looked really bad, but was still popping and banging. Cheers for the help. Will let you know when gaskets are fitted if it stops

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Julie Spider :~)

That's how mine were - they had literally been eaten away and disintegrated! That was on a '94 3YF, which I bought in '99 when it was five years old. Your gaskets would be 22 years old!

FYI - There always used to be a choice of copper or aluminium (OE) composite gaskets. The aluminium ones seal better, but fall apart and the copper ones last longer but are more difficult to compress tightly.

Quick check on Wemoto and both types are still available...

Aluminium: http://www.wemoto.com/bikes/yamaha/x...uminium_fibre/

Copper: http://http://www.wemoto.com/bikes/y...ront_-_copper/

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thank so much for your help, will make an order with Wemoto 2moro. Do you have any preference to copper or Aluminium? I was thinking aluminium and just change them every year or so, They are very cheap to get and its really hard to get a good seal on them so if they fit better surely its got be the better option?

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Julie Spider :~)

That's what I would/did do! They are much easier to get a good seal.

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