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

Mobile chicane · Veteran Member

Mechanical noise at high ish revs and on over run

TTRfan · Super Guru

A simple visual check for cam chain wear that can be done is to remove the tank and cam cover and put the engine to TDC.

If the cam chain isn't worn then the timing marks on the cam sprocket should be almost exactly parallel with the head casting as in the pic below:

Worn timing chain marked.jpg

If they are not in line, for example they are in the position of the blue lines on the LH sprocket, then this usually indicates a worn cam chain.

The chain isn't expensive to buy (see here) but time consuming to replace as quite a bit has to be stripped out to fit it.

Brian

blackflyer · Member

Hi, I would be very careful running the engine if the cam chain is worn. This could be very fatal if the chain slips a tooth then you will end up with bent valves's.

Might be best to invest in new chain now. I've just done mine you can get Yamaha original from Totally ttr's for a fraction what it will cost on Ebay.

Steve.

TTRfan · Super Guru

I have just updated the timing chain fitting guide here.

If you (or anyone else!) use it, please let me know if and how it can be improved wink

Brian

ttr steve · Super Guru

Thanks Steve

Just off to post Giles one now smile smile

blackflyer · Member

No Prob's,

Keep up the good work.

Let me know if you ever get short of stock.

I have around 300 switch gears and 500 indicators 500 cables etc. I bet there are a few ttr ones in there.

No I'm not a compulsive hoarder, I do autojumbles at Kempton park and Ardingley.

Steve

Mobile chicane · Veteran Member

Looks a bit out of my comfort zone I may get a more skilled friend to assist (do it for me for beer money)

Mobile chicane · Veteran Member

Bike washed, tank, seat and side plastics removed and re washed, I have friday off so I'll make a start on the job then.

Also managed to get my garage cleared out today so more space to work on the bike.

Hoping that the bits turn up monday/tuesday.

blackflyer · Member

You should be ok if you follow the step by step link.

Not rocket science. And there seems to be a lot of support on here.

Steve

Mobile chicane · Veteran Member

So I thought I have a free couple of hours last night I'll just get the prep work done.

1 3/4 hours later:

oil drained

back brake lever off

exhaust off

suspension reservoir (or whatever its called) zip tied out of the way

clutch cover off

cam top cover off

clutch plates and basket off (this was way to easy)

oil pump ( I think ) idler gear off

chain tensioner off

chain tensioner runner off

old cam chain off ( after making copious notes regarding positions of various rotating parts)

New cam chain on.

then it was dinner time.

ttr steve · Super Guru

Well done smile You don't hang about! Have you found anything worn yet?

Mobile chicane · Veteran Member

Right easy day at work so home by (ahem) 12 ish.

No signs of wear although the new chain looked everso slightly shorter than the old one when comparing them side to side.

anyway got the tensioner back on and cycled the engine a few times via the 14mm bolt on the flywheel and its all good.

Fresh oil and filter spin it on the statrer with the plug out to get the oil into the engine then plug in and fuel tank back on.

fired first time and tickes over smooth however the noise is still there but a bit less obvious.

www.youtube.com/watch

video of the noise.

the bike pulls well in all gears and seems to have almost all of its quoted 28 bhp.

ttr steve · Super Guru

Hi Giles

Had a listen, but from here it is impossible to tell where it is coming from. Have you tried listening with you ear at the end of a screw driver and move it around the engine to try and pin point where it is coming from?

I see it has a blanking plug in the decompressor part of the head, was any of the internals in the top of the engine?

Mobile chicane · Veteran Member

not that I could tell steve.

I also cleaned the filter in the bottom of the engine on the clutch side.

I will have the rocker cover off again and have another look.

I did have the flywheel generator cover off as well and found no obvious signs of wear, the one way bearing when spun by hand feels free and smooth and as its on over runn I dont think its that.

I have yet to have the valve clearances done ( I tried to measure and got lost in the haynes book of confusion) so I may take it to my local MX engine guy an see what he thinks.

The noise sounds a lot worse on the video.

Mobile chicane · Veteran Member

Also as can be seen the filter that ran for 20 ish miles with fresh oil has a lit less debris in it

ttr steve · Super Guru

That's quite a bit for 20 miles cry

Have you checked the magnetic sump plug?

Mobile chicane · Veteran Member

Tbh most of that stuff may have been grit from my garage floor, I only found 3 tiny metal slivers before I dropped the dam thing on the floor with my oily hands

yep nothing on the magnet and the stuff on the filter may be debris still in the system from the last time.

I'll drop the oil after 100 miles and have another look.

-- Edited by Mobile chicane on Thursday 6th of October 2016 07:17:04 PM

ttr steve · Super Guru

Sorry I am being a bit of a dummy, if the blanking plug is there, the internals would not be.

Mobile chicane · Veteran Member

So I took the TTR to my local mx guy who reckons its possibly an auto decompress unit on one of the exhaust valves which kind of makes sense.

I then did about 35 miles on roads and byways varying my speed from 5 mph to 65 mph which is as fast as the bike wants to go.

the bike seems to pull well in all gears and apart from a small oil weep on a gasket I need to replace it seems fine.

I did do 60 mph for about 3 mins then slowed down and got no smoke but a few pops and bangs so I suspect the carb is not jetted right for the straight through loud end can.

I'd like a quiter exhaust TBH as I mostly use the bike on trails and byways and I'd rather not iritate the locals.

Unless antone fancies having a go at the valve gaping for me I'll take it to the mx guy and get him to do the lot.

It could be that the valves need cleaning as they could be sticking.

PlumasDude · Senior Member

Bashplate loose? Had a scary noise recently and it took me 2 hours of frustrated wrenching to realize I had a sheared bolt on the plate.e

ttboof · Super Guru

Agree a loose bash plate can do it as can the engine mounts I had the rear one stil fairly tight but I thought I had serious trouble nipped it up and it was all ok

And of course the front sprocket case saver usually needs a bit ground off the trailing edge both of the latter only happen on the move .

Bash plate can get vocal anytime

TTRfan · Super Guru

Mobile chicane wrote:
So I took the TTR to my local mx guy who reckons its possibly an auto decompress unit on one of the exhaust valves which kind of makes sense.

No auto decompressor on the TTR250 confuse

Some were fitted with a manual decompressor but they are very rare.

ttboof · Super Guru

just thought of another good noise producer on the ttr the heat shield on the header and the join betweem the header and muffller if they are loose they cause some interesting rattles

i had a tt250 years ago thet cracked the head. I replaced the head with a head off an srx 250 road bike which had a decompressor fitted the spring kept it out of the way but have never seen one on a ttr

-- Edited by ttboof on Wednesday 12th of October 2016 09:57:07 PM

Mobile chicane · Veteran Member

ok update time I've fitted a magnetic sump plug, fresh oil and fresh filter and done about 100 miles on road and trails.

I've also fitted the ttr decompression plug thingy which still weeps everso slightly but I think thats because I may have nicked the rubber O ring when fitting it.

The noise is still there but the bike still starts fine and revs up fine.

The bash plate is not the issue its definatley somthing inside the engine casing.

I need to replace some gaskets so I'll drop the oil and inspect the filter at the same time hopefully no more metal flakes.

The sprag clutch is very noisy when starting so this may be causing the issue.

I am planning on replacing the TTR with somthing with a larger engine and / or more power as I ride a fair distance to the trails I use and 65mph flat out is somewhat painfull.

I also cant whellie it off the throttle which I wanted my trail bike to do.