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

jonnywrestler5 · Newbie

valve seals help

TTRfan · Super Guru

Hi Jonny and welcome to the forum!

You don't need a valve spring compressor to remove the valves to change the valve stem oil seals if you have strong thumbs wink

Whereabouts in the rebuild are you?

Are you stripping the engine down or are you in the process of rebuilding it?

If you haven't started to strip the engine down then you have no need to worry about lining up the cam chain sprockets as you have the chance to do this after the head is screwed down and you are replacing the camshafts.

If you have put the engine back together again then if you remove the cam chain tensioner this will give you enough slack to line the sprockets up properly.

I am assuming you have downloaded ot otherwise obtained the workshop manual. If not, it is an invaluable aid and one of the best I have seen. It only goes wrong for me when I think I know what I am doing and don't follow the manual disbelief

Any more question then just ask us.

Brian

jonnywrestler5 · Newbie

ok, I was nervous about needing a valve spring compressor to switch out the seals.

at this point, I am waiting for the top end gasket kit to show up. I have the cylinders and piston off to clean and wait for the new rings which wont be here until next week. I am cleaning the gaskets and all of the residue off the motor. Its not a rebuild, just a fix.

I appreciate the help.

TTRfan · Super Guru

Nice one Martyn but its a shame the valve spring compressor they use won't fit around the recessed springs in the TTR head cry

My thumb pressure technique requires a tool of some sort that allows you to get the colletts out (I use a magnet as per the video) when you have the spring compressed. This is a pic from my refurb project showing how I do it and you can see there is quite good access to the colletts. The tool I used was from my valve spring compressor kit but you may find something else that will do the same job:

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A quick way to get the collets back in without using the valve spring compressor is to line the collets up as close to their final position as possible and then give the tool a tap with a hammer and the colletts usually drop right into place.

For these techniques to work you have to put a rag or something under the head so that it stops the valves falling down.

As Martyn says, make sure you clean up the valves and grind them in to get best performance from your rebuilt engine.

Are you going to hone the bore? There are lots of opinions on the pros and cons of that

Good luck!

Brian

PS If you aren't sure how to describe a part then why not refer to the numbers on the fiche diagrams here wink

jonnywrestler5 · Newbie

I am in the process of scraping the old gaskets off the cylinder head. The only gasket that is giving me trouble is the one that surrounds the piston chamber (idk how else to describe it). Its really thick and stuck on there really good. I am being very careful to not scratch or damage the cylinder surface. I went to a local auto parts store for ideas and they had this foaming gasket remover. It worked great on the leftover residue from the gaskets that came right off but not so great on the other one that is really stuck and burnt on. any ideas on how to soften that gasket to make it come off. I am using a gasket scraper but I don't want to push too hard and hurt the surface.

which way do I push the valves to change the seals? Do I push on the valve surface? I tried to push a little bit and then stopped because I was unsure if I was doing it right?

This forum/site is helping a lot. Thanks guys.

Cubber · Super Guru

Here's the advice of another site's subscriber on the topic of stubborn gasket removal:-

"Tired of scraping gaskets that refuse to be removed without taking aluminum along with it? Here's what you do; smear a strong paste type paint and varnish remover on the gasket, let it set for about 5 minutes and you'll be amazed how easily the gasket will lift off. Those that have become a permanent part of the engine case may have to have the surface of the gasket shaved off with a super sharp wood chisel for the remover to penetrate. But it WILL come off!"