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

mine does it no.idea what it is 

but it has to be realy hot and riden way harder than usual  eg racing social grass track on a 40deg day  .stop for a couple of minutes and its all good 

Thanks for the response Les. What a coincidence that your TTR does it!

What do you think about where the noise might be coming from - a bearing or a rotating part rubbing on a casing - clutch or gearbox?

As I said, I am baffled 

Some more information about this noise.

It starts after the bike has warmed up a bit.

Nothing specific makes the noise start.

It sound s like a screeching noise, similar to when a bearing is run dry, or breaking up.

The noise does not change with revving the engine and does not change when I pull the clutch in and out.

The noise does change pitch as I go through the gears to slow down and the noise stops when I come to a stand still.

The noise seems to be coming from bottom part of the engine

I change the front wheel bearings, thinking it was that, wasn't not changed the back ones yet, but does not sound like it is from there.

I have tried moving the speedo cable with my foot when the noise starts, but this seems to make no difference.

The noise comes and goes at no specific intervals, done it about 8 times on a 2 hour ride yesterday.

I managed to get the bike to do it earlier, by riding around my field for 15 mins, when I stopped the noise went, I did manage to record, but I am not having much luck getting it on here. Will try to get it on here later.

Any help would be appreciated

Like someone running their nails down a blackboard sort of noise, and a bit metallic.

Interesting about the castrol 4T oil. Im using that oil now. Although my machine dosent get to hot as i do limited track ridding. 

When mine made the noise it  was. In line with engine speed and stayed at idle in neutral  which narrowed it down a bit 

I'd have a quick listen and shut it down  would be ok once restarted .very strange.

Sure you didn't drop a filling in there or something Brian?!...

as its comimg from trasmision .a long shot is there anything odd round the front sproket case saver .chain slider /guide 

i thought i had somthing nasty internal it turned out to be the shock guard touching chain ( I had fitted a non genuine guard and it was 6mm wider)sounded like out put shaft or gear problem each time i got off it would look ok once the weight was back on it fouled . -- has hter been a change of tire --guard -- chain and sprockets

also I saw someone on the forum had found a front sprocket fitted back to front . the rear engine mount can make some pretty strange noises but prob not this one

just thinking

Sixpence none the wiser!

Nothing to see here.....................

The engine is pristine - one of the cleanest I have ever stripped down!

I drained the oil into a clean light-coloured container and it was clear with absolutely no sign of foreign objects or swarf. Nothing on the gauze filter and the oil filter is like new.

I fished around the sump with my screwdriver extending magnet and there isn't anything loose in there.

All the shafts rotate freely with no feeling of roughness and no play.

The sprag is perfect as it should be coz it's a new one!

The clutch was renewed recently and both metal and friction plates are near perfect.

There were some suspicious rub marks on the outer clutch basket but it is clear from looking at the casing that it hadn't been rubbing. Some kind of manufacturing marks I guess.

The only flaw is a missing thrust washer on the small idler but no way would that cause a screech.

peteBLUEttr wrote:

---

Defo some scratch marks there on that clutch..

---

There weren't any corresponding marks on the casing Pete which makes me believe they were on the casting before installation.

I had a look at a couple of my spare clutch baskets and they are showing the same "scratches" - see below - so I am ruling that out.

I am going to leave the engine open just in case any of you guys have some ideas.

Meanwhile I have been looking for external reasons for the screech.

First off, I tried the upper roller bearing which felt rough and wasn't turning smoothly. Took it off and it wasn't the correct one for a TTR so have fitted a new one.

Looking around the chain run, I found the lower chain block/slipper had been fitted the wrong way around. Easily corrected!

I eagerly took the lower guard off completely to check for any rub marks from the chain but, sadly, it was fine 

The upper chain roller might have produced a screech with the right harmonics so, with the new roller, that's been eliminated from the equation.

Unfortunately I haven't heard the screech so am working blind to a certain extent.

Next up is to get the rear wheel out and check the caliper/pads/disc/bearings.

Brian 

Quite a bit of labour and parts now....... I'm defo interested to find out what it is!..

Spoke to Steve again this morning. The noise changes pitch as he cogs down. In which case the only components that could cause this would be associated with shaft 1 as shaft 10 would not change speed of rotation with the gear changes.

So I am thinking bearing 8 or 9 has a problem.  

Anyone think of anything else that would show the symptoms?

Brian

Back on the case!

Ready to split the crankcases having removed the Allen bolts. I put them through a bit of cardboard so that I can make sure they all go back in their correct position.

Splitting the cases can be a bit problematical but there is a little drain slot on the bottom and it shouldn't take much to lever them apart with a small screwdriver. This avoids causing any damage to the mating surfaces.

The suspect bearing is on the LH side casing. I wanted to get it out without damage to check if it was running freely so used the grease trick rather than my blind bearing puller.

Fill behind the bearing with grease.

And then tap it out with a good fitting rod. A 3/8ths socket extension was perfect. You will need to top up the grease as the bearing moves outward.

And out it comes.

It is slightly odd that the bearing had a seal on its inner side as it runs in oil so why not have it open on both sides 

The bearing seems to spin freely with no rough spots or rumble feeling so am still not convinced I have found the cause of the screech. However, I will order a new one to fit and see if it is the same design.

Going back out after a cuppa to have another look at the gearbox innards and search for any other clues 

Brian

Why not get new bearings from some where like http://simplybearings.co.uk/shop/ ? They stock quality bearings by Koyo and SKF.

locky wrote:

---

Why not get new bearings from some where like http://simplybearings.co.uk/shop/ ? They stock quality bearings by Koyo and SKF.

---

I am worried that the suspect bearing may not be original and I would be interested to know if the original had a seal one side. Anyone know?

Still waiting for the bearings for Steve's engine so, to keep him on the lanes, a loan engine has been fitted.

Ready for transplant:

The engine hadn't been started for a few years but started up right away and is running fine.

At least I will have a proven good engine spare when Steve's own engine goes back in 

Brian

Wahoo - the bearings arrived today for Steve's gearbox. They were part of a delivery that got "lost" by the courier. Funnily enough my claim for compensation resulted in the parcel being found 

The smaller (LH side) bearing has the seal but why 

I am focused on fitting these bearings with the least possible opportunity of damaging them in any way. I had some bearing drivers made up for the front and rear wheel bearings which prevent causing any damage to the bearings and their seals (as can happen when driving them with a socket) and was hoping that I could use them but the rear wheel bearing driver is too small and doesn't sit on the outside race. However the front wheel bearing driver has the perfect outside diameter but the centre mandrel is a tad small which might allow it to move.

I am tempted to get some drivers made up but is it worth it for the amount of use they will get? The thing is it is probably cheaper to get them made up than the bearings cost. A bit of a puzzle 

Brian

Let's hope you have found the culprit, as on the Okehampton ride out, no noise at all with the spare engine.

Is the smaller bearing seal point to the outside of the engine? extra seal to stop ingress of dirt or oil leakage?????

I test fitted the side casing and sprung tensioner wheel this evening to check the gear change was working properly - and it is 

The photo below shows the gears in neutral. There is an odd shaped cut out on the changer which is where to find it.

Next job is to change the other bearing. No 8 in the fiche pic included earlier on in this thread.

Didn't reckon I had much of a choice so decided to pull the bearing!

This was the first real use of my internal bearing puller.

The first job was to find the best fit tool to go inside the bearing, put it through the inner race and then screw it down to make sure it was tight and gripping the race.

Next up, attach the slide hammer and give it some welly:

To be honest it didn't take too much effort and I am well pleased with the puller - an excellent bit of kit!

So the bearing is a NSK 6203DLA8.

A replacement NSK bearing was easily found/ordered and will hopefully be here mid week

Gives me a breathing space to clean the crankcases faces and check all the case bolt threads are in good order.

Brian