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Hi, I just bought a ZXR400 L5 , no service history to speak of, I am new to ZXR's but read somewhere that the cam chain needs replacing at 20k miles?, the bike has done 34k miles, the chain is quiet just a slight rustle at tickover, please could someone let me know is the 20k replacement interval correct?, i.e. is there a danger that they snap above this mileage, cheers .

If you take off the pulsar/timing cover, you casn see how far the tensioner has clicked out, I spose that would be quite a good indicator of how slack the chain is, as the tensioner takes up the slack, although there are 1/2 other tensioners. If you want complete peace of mind I would replace all three tensioner blades at the same time as the chain I think it depends on how many of those miles its spent at redline, and chances are probably quite a lot lol

Definitely been on the redline a fair bit, the previous owner has used it as a track bike, seems to have kept on top of oil changes etc but as you say for peace of mind I will change the lot, thanks.

Yeah its not surprising I find my zxr so much faster to ride than a friends sv 650 (mainly in the corners)

You'll probs know this/do this anyway, but whilst you've got the engine out to do the chain and blades you may as well replace the head gasket as they tend to go around that sort of time apparently, you may have to get the head skimmed at the same time, might take longer now, but you won't (hopefully) have the drop the block for another 15-20k Good luck!

There is absolutely no need whatsoever to replace the camchain 'just in case', it is not a consumable item like a cam belt. Neither does it make the slightest bit of difference whether or not the bike has been red-lined - it is designed to run to the red line. There is also absolutely no need whatsoever to replace the HG 'just in case' and you won't have to have the head skimmed unless the head has already warped and the HG blown (which it hasn't). Save your money and only do these jobs if and when you have a problem. It makes about as much sense as replacing the cams 'just in case they pit'.

So you're telling me, a bike run on a track at redline a lot won't need its cam chain replacing earlier than one used mildy on the road? And would it be cheaper and easier to repair the carnage of a snapped cam chain then? Tirpitz you're obviously not like me, I would rather have the reassurance of knowing that everything is in order (especially on an ex track bike that you don't really know the history of) and also you would rather have to do these repairs when they fail unexpectedly?rather than do it when it suits you and you don't need the bike to get to work etc... Anyway its just the way I do things,

Camchains do not 'fail unexpectedly' as a rule. They wear out over time, like other chains do. It is almost unheard of for a camchain to snap unless something else fails and they get jammed. They stretch because the pins get worn and the tensioner takes up the slack. When the slack exceeds the service limit the tensioner can no longer take up the slack and the chain starts to rattle, which you can clearly hear. That is when you do the job. Just like you would replace a final drive chain when it has worn out, not 'just in case'. You're telling a bloke who has a silent camchain that he ought to replace it 'just in case' - total waste of money. If the bike had done 34k and the chain is making no untoward noise then there is nothing wrong with it and it might even have been replaced, hence why it's so quiet. If you want to waste your money that's up to you but don't panic the guy into wasting his with tales of snapped camchains and blown HGs.

Tirpitz wrote:Camchains do not 'fail unexpectedly' as a rule. They wear out over time, like other chains do. It is almost unheard of for a camchain to snap unless something else fails and they get jammed. They stretch because the pins get worn and the tensioner takes up the slack. When the slack exceeds the service limit the tensioner can no longer take up the slack and the chain starts to rattle, which you can clearly hear. That is when you do the job. Just like you would replace a final drive chain when it has worn out, not 'just in case'. You're telling a bloke who has a silent camchain that he ought to replace it 'just in case' - total waste of money. If the bike had done 34k and the chain is making no untoward noise then there is nothing wrong with it and it might even have been replaced, hence why it's so quiet. If you want to waste your money that's up to you but don't panic the guy into wasting his with tales of snapped camchains and blown HGs.

As ever..................