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

Spyrious wrote:

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I ordered some eBay hall sensors. Am i supposed to remove the "glue" from the unit in order to access the small pcb?

What is the safest way to open it?

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Hi Spyrious and welcome to the forum!

I have not done this job myself because my eyesight and hand control aren't up to working on such a small part 

My recollection is that the black potting compound used is some sort of epoxy but can't be certain.

Here is a video showing one method - https://www.youtube.com/watch?v=OiPe6f4Oh8E

Search Google using the search term "how to remove potting compound" and you will see that there are several different ways to remove it but some don't seem very safe 

If you get stuck then "TTR Steve" offers an exchange service - see here.

Brian

Thanks for the reply. So I have to buy the sprag clutch too?

Welcome to the forum.

Top advice from Brian as usual 

Welcome to the forum Spyrious.

I echo what Steve said and confirm that Brian doles out superb advice - he's been there and done it before us all.

I can also say that if it wasn't for Steve's superb TTR shop there would not be the percentage of TTRs still running.

Martyn

 

The usual cause of the damage is a worn sprag "kicking back" when the engine shuts down. I doubt the Wiseco piston would have made this any worse. 

With a new or good sprag, the parts are perfectly serviceable and don't require strengthening.

Brian

-- Edited by TTRfan on Friday 15th of February 2019 05:33:37 PM

There is a small oil leak around the valve cover.I removed the cover to replace the gasket.I found a little plastic plug on the left side of the cylinder head.Right behind it is an oil drain bolt.Is it replaceable?I didn't found it on the parts fiche.

Unfortunately as i unbolt parts i found more problems.The left intake cam retainer is cracked.Any hints how to fix this?Many thanks

-- Edited by Spyrious on Sunday 24th of February 2019 02:37:05 PM

Bad news about the cam cap. There are a couple of possibilities if you know some properly skilled mechanics:

One is to get someone to TiG weld along the crack as much as possible. It will need to be done in place with the bolts nipped up but not fully torqued, so that it doesn't go too out of shape and the cam shafts (and everything else) well protected from weld spatter. After it's done check the camshaft still turns easily. You need a very skilled welder.

Another is to TiG weld it up removed so that it can be welded all the way round the 4 sides. You then need a machinist to line bore it to match the original surface. If the surface is too damaged, a split phosphor bronze bush can be made to fit and line bored to the original dimension. You need a skilled welder AND a skilled machinist!

Two small holes drilled at 45 degrees, tap a thread in and bolt the 2 bits together. Very fiddly job!

Finally, and the easiest to try: cut a flat surface on the larger piece level with the flat surface that the bolt face on the smaller piece seats on and put a thick, hard washer under the bolt so that it tightens down on both pieces. If you are lucky, the two broken bits fit together neatly like a 3D jigsaw, so the bolt holds it all together. Don't cut too much off the large piece or you will lose the threaded bit that the cover bolt tightens into, and don't use such a big washer that the cover doesn't seat! Sorry if that is difficult to read - if I knew how I would draw you a diagram!

Sorry, there is no simple fix for this one I think, and whatever happens, the camshaft must turn freely when it's all done. Finally, don't overtighten the valve cover when you put it back together.

Good luck!

Simon.

-- Edited by mossproof on Sunday 24th of February 2019 06:42:40 PM

Thanks for the link steve!
Mossproof do you mean something like this?
Cut the part in red,and put a washer blue to sit on both surfaces?
i.postimg.cc/5tbwD9rZ/IMAG2239-2.jpg

Also.I know from other bikes that the cap and cam are matched from the factory.Is this true for the ttr250 too?Or can i search for a used cap and be done?

Thanks

(Why do my posts disapear wheni edit them?)

That's it exactly Spyros. Certainly the easiest method to try first. Because of the angle of the crack, and the angle of loading on the bearing, you might get away with it.
The caps are matched by being line bored at the factory, but with Yamaha quality there's a chance another will fit as John says. The "engineers blue" is a good way to check for tight spots.

-- Edited by mossproof on Sunday 24th of February 2019 08:41:00 PM

ok.it looks like i found some used caps.Will know tomorrow for sure.To replace them i believe i have to remove the tensioner .Correct? Like when replacing valve shims?And is it really that easy to remove material with an stanley knife?Thanks

I managed to put the bike back together.The cam cap i found was almost a perfect fit.I just had to sand it a few times with a 1500 grid sandpaper.Replaced both broken gears,replaced sprag and new generator cover.Most broken parts where trapped on the flywheel.The oil filter cached the rest.I will do another oil change after a few kilometers.I also replace the spark plug and the cam cover gasket.Fitted the bash plate and new tires.I dis the speedo sensor fix with a hall sensor,but it wasn't successful,anything else i can try?I only rode it to work.Rides ok.Only thing that troubles me is that the starter seems to struggle to turn the engine,but eventually it fires.But it seems to me it spins the engine slow.Any clues?I will post a pic soon.
Also i want to than you all for all the help!!!

Go here and a couple of posts down you will see how to check the starter motor independently of the starter switch and solenoid.

If it doesn't turn and tapping the starter doesn't get it working then it has worn or sticking brushes in which case you need to remove it to check.

This thread might be helpful - https://ttr250.activeboard.com/t58726320/starter-motor-removing-and-replacing-a-starter-motor-plus-ch/

Brian 

99% positive that new brushes will solve the problem if the old ones are worn or sticking!

https://totallyttrs.com/epages/699105d9-e4cc-4b32-b236-84e72cd67f84.sf/en_GB/?ObjectID=7743517  - might be worth asking Steve when they are likely to be back in stock.

The big O rings are normally in a bad state and stretch such that they don't go back properly. They need to fit properly to keep water out. It's worth buying a pair in advance - see here

Ok today was a success.I made my first ride with the ttr.Was a blast!!!Here is a pic

i.postimg.cc/8PHDcJND/ttr250.jpg

Glad it all worked out. Well done!
Tidy looking bike.

Bike looks sweet and that view is awesome 

and nice colours on the bike too 

Beautiful picture...where in Greece Spyriouys?...you live in the land of the Gods!

what silencer you got there looks good not as clumberson as the stock pipe