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

dj9ten · Veteran Member

How to check valve clearance

TTRfan · Super Guru

The engine parts look great - should be a nice runner when you got it fixed.

Valve clearance adjustment covered here

Lots of other "show and tell" guidance here

Hope it all goes well and you get the TTR running.

Brian

dj9ten · Veteran Member

In the process of inspecting everything I found this......how can i get it scrwed back in level ? It's stuck ....the one for the rear seems fine it's just the one in the front that's come out while trying to get the nut out

TTRfan · Super Guru

Can you borrow a stud install tool like this one?

Otherwise Vice grips on the collar might do it. But they will leave some biggish bite marks!

pug · Guru

tip 3
Try locking two nut's one against each other on the thread then wind down the top nut should turn it back in it always works for me

dj9ten · Veteran Member

Thanks guys ....the 2 nut method work after letting it sit in penetrating oil for a while .....backed it all the way out cleaned the inside of the threads up w q tips and used the same 2 nut method to turn it back in....you guys are awesome !

ttr steve · Super Guru

Don't think anyone can beat a Bri/ Martyn techno combo biggrin biggrin biggrin

heffh084 · Veteran Member

TTRfan wrote:
The engine parts look great - should be a nice runner when you got it fixed.
Valve clearance adjustment covered here
Lots of other "show and tell" guidance here
Hope it all goes well and you get the TTR running.
Brian

Hello all,

I've been away from the forum for a while, as my partner Anna's TTR has been running like a dream all the way through our trip through Russia to Mongolia and the occasion green lane in the UK since.

But now I am need of advice as it came to the time where some major maintenance was necessary.

At the same time we decided to fit the 325 kit from thumper racing and during the rebuild, after having the engine, barrel and head modified by a machine shop, I noticed my camshaft clearances are very low , without shims installed.

I'm getting 0.017 and 0.015 thou on the inlets and 0.007 on both exhausts, again, with no shims fitted.

I found this after fitting the shims I took out pre machining, and when I tightened the camshaft caps down, the camshafts would not turn, and had no measurable clearance.

So ive taken the shims out and I'm measuring the clearances above.

I had the valve guides replaced for new, and the valve seats re-cut. But by my math, the engineers have removed upto 1.35mm of material from the valve seats/valve faces, meaning the top of the valve stems sit 1.35mm closer to the cam shaft lobes.

There is no shim that I can buy that will take the inlet clearances into spec as they are all too but, starting at 1.20mm.

Question is, can I run without shims fitted, or am I looking at new valve seats to sort this problem?

I don't want to continue with the rebuild of the head until this problem is sorted as it could prove to be even more costly, especially if the current cable seats are too thing to dissipate heat effectively now I've the big bore kit fitted.

Many thanks for any advice you can all give, we were so looking forward to getting the engine back and rebuilding it, but now we have this disappointing problem to deal with. :'-(

ttboof · Super Guru

Will see what others have to say but no shims should be OK as long as there's sufficient gap (haven't come across it though) in the cases when seats and valves are machined in other engines I've also taken a bit off the top of the valve stem to allow for the machining keeping the need for shims

pug · Guru

Stick with shims in take the extra off the Valve head to bring it within adjustment of the shims if you don't have the tools to do it take it to a engineers shop its best dun with a Lathe and tool post grinder. But can be dun post apocalyptic Mad Max hard times with a bench grinder a good eye and a calliper gauge

Pug

TTRfan · Super Guru

Hi Howard and good to hear that Anna's TTR ran well through Russia and Mongolia - probably all to do with your excellent preparation smile

Your measurements of the existing clearances are in thou and Google reckons 0.017" is 0.4318mm, 0.015" in is 0.381mm and 0.007" is 0.1778mm

I would be wary of letting the cam caps run directly on the valve spring retainer or valve stem so one solution would be to thin out a 1.20 shim to what you need. Some motorcycle engineers do this as a matter of course to get the exact clearance they want.

You say that the machine shop re-cut the valves. Depending on how much they removed, new valves might restore some clearance although an expensive chance to take unless you can compare your valves with new.

Les's and Pug's suggestion of machining some material off the top of the existing valve stems sounds a good solution and give you the possibility of adjusting clearances in the future if required.

I think you may need to account for valve clearances reducing with wear as valve heads bed into their seats - is that right Les/Pug?

I prefer the thinning out of shims solution wink

Brian

ttboof · Super Guru

Agree thinning the shim is a good option

Taking a bit off the valve stem is usually done in a machine shop so the end is square and contacts the shim properly

Agree clearences tend to close up as valves settle in and the seats wear

heffh084 · Veteran Member

Hi all, thanks for the quick replies.

I am going to go over everything again tonight as after phoning the engineer who carried out the work, he assured me that he only took off a max of 20 thou in refacing the seats and valves.

With that in mind, as I was running approx 1.80 mm shims beforehand, so now he's removed a max of .508mm (20thou), it stands to reason I should require about 1.30 mm shims.

He suggest that the shims weren't sitting on the valve stem heads correctly, but instead, sitting on the valve spring caps somehow, in turn raising the cam followers. Not sure how that's possible but I will get a fresh set of eyes on it tonight and report back tomorrow for anyone that's interested.

I could grind down shims, but currently, the biggest shim I would need is one that's only 0.18mm thick. Not sure that would stand up to the load very well?

Brian, were you still after the new dimensions for the 325 sleeves supplied by thumper racing?

TTRfan · Super Guru

heffh084 wrote:
Brian, were you still after the new dimensions for the 325 sleeves supplied by thumper racing?

Yes please!

heffh084 · Veteran Member

Hi Brian,

Here are the dimensions of the 325 sleeve I was sent, at least according to my £20 digital caliper

heffh084 · Veteran Member

So I was just about to assemble the head for the last time post valve clearances and when I turned my head upside down, one of my spring seat fell out.

Odd I though as usually there is enough oil to keep them sticking to the head.

On popping it back in, I've noticed the seat rocks on something. A bit of grit I thought.

Nope, looks like the engineers who rebuilt my head have not fitted the valve guide retaining clip in fully, so the spring seat can't sit flush on the bottom.

Is there any chance I can reseat the valve guide at home? How much heat do I need to apply to allow the guide to press out? Can it be done with a heat gun? Or if I put the head in the oven for a short while at 100°, will that allow me to press the seat out, reseat the spring clip and press the guide back in?

Or am I best taking it to another machine shop and spending yet more money?

Many thanks for you help again!

Black8driver · Veteran Member

personally i would take the head back and get them to sort it but can understand after your problems that you may not want to take it to the same place
maybe get another place to have a look maybe report on the previous work.. im not sure what you have paid for exactly but if i was re-conning a head or even cutting seats i would also be shimming the valves/ to set clearance at the same time it shouldnt be your problem of making custom shims if they have cut the seats too deep.. it would also have an effect of having less spring seat pressure too unless they have made more spring seat shims to compensate..
im asuming all this of course as i cant be certain hwat you have asked for or been charged for but it all sounds a little dodgy..
si

heffh084 · Veteran Member

I asked them to replace the valve guides, and recut the valves and valve seats. I didn't supply the camshafts but now I realise I should have, but they didn't ask for them either.

Still, I've got the valve clearances set now, but it's just this valve guide clip that's not right now.

Sadly the machine shop isn't local, so I'm reluctant to pay for shipping both ways. I think I'll take the head to a local guy some stock car guys have recommended. Hopefully he can reseat the valve guide with the clip in the right place!

dlee22 · Senior Member

Valve clearance issue

TTRfan · Super Guru

I think it very unlikely the top of the valve stems will have worn.

What I think is more likely is that, over time the valve head wears, along with its seat, and it gradually sits into the head further thus reducing the clearance at t'other end.

Brian

dlee22 · Senior Member

Ahh okay, in that case a pair of new valves will be needed then?

Can the seats be removed from the head and replaced?

Thanks

TTRfan · Super Guru

Get the head off and check all the valves and seats before spending any money. If the valves have a definite ridge on their seat surface (or are pitted as I have seen occasionally) then get new ones. It is less likely that the seats will be worn as I think the valves are designed to be the sacrificial part.

If you have to buy new valves then you may be lucky and they will grind/lap in evenly. Otherwise the valve seats might need re-cutting, You don't really want to do that if it can be helped as it puts the stems up in the head a fraction....

Don't forget to fit new valve stem oil seals whilst you have the valves out!

Good luck - if you need help or advice just post up a message biggrin

There are a few guides that may help e.g. this one.

Christos · Veteran Member

Valve clearance check

Christos · Veteran Member

Any suggestion?

mossproof · Super Guru

I don't check mine unless there is an unusual noise or the engine is not running properly! 2000km seems a bit KTM!!
Probably somewhere in between is most sensible, say 10000? (My TDM850 manual says 40,000!)

Christos · Veteran Member

Thank you Simon!

oshanrube · Veteran Member

what kind of noise should i expect in case the valve clearance is off? and in case its off, there isnt a screw method to tighten right? in the manual it says we need shims , that means it should be something which goes to the dealer?

TTRfan · Super Guru

Have a look here to see if you thiink you could do the work yourself wink