engine rattle

hi all over the past few weeks my cb5 has developed a slight rattle on the engine it appears to be comming from the top of the engine, when the bike is 1st started up and cold there is no noise whatsover from the engine just a nice whirling noise but once warmed up there is a intermitent rattle, The bike has 23,000 mile and the valve clearences were just done at 19,000 so i dont beleive it could be that and it would make a tapping noise rather than a rattle anyway so just off reading other posts on here it could be the camchain tensioner what needs replacing, When it 1st started to happen it would be every 30sec or so you would here a slight rattle now it is gradually getting worse and happening every 10sec or so in between the noise the engine purrs like a kitten and the bike runs and performs very well, any suggestions would be gladly appreciated cheers colin.

this might sound daft, but could it be something that's worked loose? a nut or bolt rattling around on top of the engine? maybe something else that's found it's way under the tank? Cable stay on the choke? Can't imagine the plugs or coils working loose but they may be worth a check(?)

Thanks for reply no its defnatly from engine internally

Sounds like the cam-chain tensioner to me: mine started by making an noise very occasionally that became more frequent. Depending upon how much you like to risk these things you might be able to 'get away with it' for a while until the noise gets a bit worse - I didn't, I replaced my cam-chain tensioner, it is up to you...

cheers i think i will be replacing it soon i can get one from tippets for £45 pound, are they easy enough to do i have a haynes manual i might try myself.

eternally_troubled wrote:not too difficult, especially if you have some small spanners and/or a small 1/4" socket set.

Don't you need a locking tool for the plunger? I've never done one, I just recall it from Haynes.

Thanks for the replies guys, I went to my local bike garage today and he confirmed it was the start of the camchain tensioner wearing he said he had heard a lot worse but said it would pay to do it now rather than later just to be on the safe side he said the chain should be ok just to replace the tensioner and gasket, He gave me a price between £40 - £70 depending on how long it took so i think i will leave it to the mechanic who has all the tools to do the job all i need to do is buy the part, Can anyone tell me do you get the gasket with the tensioner or do you need to order seperate cheers colin.