A forum for owners of Yamaha TTR250 trail and enduro bikes!

Wardy · Member

Ticking on over run

Wardy · Member

Ok have done the usual check for loose bits, all is good. Defo internal, cam chain?, piston slap maybe ? your thoughts appreciated.

ttboof · Super Guru

Think you have covered my thoughts already

If it's on the move maybe the case saver being hit by the drive chain

Loose exhaust guard

Loose bash plate

Next check the can chain for stretch

Before going inside

Wardy · Member

Ok, took the cam cover off and checked for stretch as in the great thread and photos by Brian, and the chain has stretched but only very slightly, similar to Brian's photo, but Maybe not so much. Put her all back together, fired her up, nice and quiet, let her warm up , give a rev and gradually the rattle appears, only when decelerating, nearly at tickover. Defo coming from in engine, seems down the bottom and not head. Any idea's guys before I start open heart surgery. Cheers steve.

ttboof · Super Guru

Everyone are prob reluctant to say go inside as its rare for ttrs to have piston slap but a possibility if it's high mileage and a lack of servicing

I don't have any more ideas other than check it has good compression may be a way to check for wear without pulling it down

A screwdriver with your thumb over handle up against your ear makes a cheap stethoscope could help narrow it down

-- Edited by ttboof on Friday 22nd of March 2019 08:43:21 AM

TTRfan · Super Guru

I think Les has nailed it and, if all external possible causes of the rattle have been eliminated, piston slap is a possible culprit.

The question is, have you become over sensitised to the noise and letting a common engine noise bug you? Air-cooled engines are always going to be noisier than their water-cooled cousins.

Do you have a mechanically-minded friend who could take it for a ride and listen and get a different perspective?

If the engine is otherwise running well and the noise hasn't reached "death rattle" proportions then maybe just carry on riding it?

BUT, if it is really bugging you, the only way forward will be a tear down to check the piston and bore cry

Brian

Wardy · Member

Thanks a lot for responding guys, know exactly what you mean about rattles, think I know deep down she needs to be opened up, will try and get a mate over at the weekend for a second opinion. Not sure of the mileage as has got a wr speedo, but have owned it for last 6/7years and been brilliant , did 2000km on tet trip last year as well, she's a keeper so might have to bite the bullet and get on with it. For piece of mind I'll know its sound. Cheers Steve.

Wardy · Member

Ok, quick up date, sons mechanic friend came round today , had a listen, and declared its a top end rattle. Sooo, as on the odd occasion I get a puff of smoke on start up as well, going to give her a top end overhaul, and a cam chain for good measure. Touch wood and all that, thanks for the responses, cheers, Steve.

ttboof · Super Guru

When doing the head service once the head is off the bottom cylinder gasket is likely to come apart or away from one surface it's a good idea to replace it as well which gives you the chance to check the piston and rings. The bit of start up smoke is likely the valve stem seals when you take the head off check the stems on the exhaust valves before you clean it for a but of oil or carbon build up usually backs up the seals are leaking and not so much the rings.

If the noise is from the top end might be the valve clearence if you can check the clearance before you take the cams out to help make sure your on the right track

Good to hear you making progress