Valve clearances need help

[Strikmabill]

Today I decided to check my valves as advised. I never did thid before but decided to give it a go and also had a mechanic mate give me some pointers. So here's what I did: Took out the coolant, radiator hoses, thermostat housing, radiator, everything I had to do according to the manual. Took out the magneto cover and turned the engine counterclockwise till the T mark aligned with the mark on the crankcase which according to the crappy pictures on the pdf manual I have should be under that little square edge of metal sticking out the crankcase towards the front wheel. Started checking the clearances on cylinder number 1, turned it 180º and checked cylinder number 2, again 180º to check cylinder number 4 and another 180º turn to check cylinder number 3. This is the correct way to do it right? My exhaust clearances are all within range but the intake are all off and under. The picture below shows what I measured.



Where I wrote <0.03 means the feeler gauge I had only went down to 0.03 and that still didn't fit between the shim and the cam lobe, so maybe they were touching and had (still do) no clearance at all. I'm not sure what to do now and can't really understand the manual due to the poor quality of both the pictures and the pointers/text.
Any help would be greatly appreciated.
Cheers.

[Evilchicken0]

Mark the intake cam wheel with a white paint dot and the same on the chain link so you know where they line up. Take the cam out (losen the bolts in sequence). Take off the cam followers and check the shim, they should be marked with a number on the underside, this is the thickness of the shim ....
Do a little mathematics and add your clearance to the shim thickness then work out if you can move a shim to bring the valve clearance into tollerance .... make a note of any new shims you need and get them from Yamaha.

Put them in, replace the cam (use a torque wrench and stick to the sequence) lining up the paint marks. Turn the engine by hand and check the tollerances agian - you won't need to change them if the maths is right.

[Strikmabill]

Cheers Evil. As I said I never did this before. I took it apart expecting to, if necessary, buy thicker shims and was caught off guard when I saw the intake were all under tolerance. My question now is having at least 2 shims touching the cam lobes how will I know how much smaller shims I'll need to get? Should I assume that those two valves aren't open and are just slightly touching the cam lobes? And another thing, at which clearance should I leave them at since the intake are all under and not over the limit? And how about the exhaust ones? Thanks.

[Evilchicken0]

The valves stretch over time ... something about the 14.5k rpm redline ... anyway take the shims out of the 0 toll valves and note the sizes, replace with the thinest that you have and put the cam back in then measure. That should give you an idea of the size you want.

Take a view on the exhaust tollerances ... you can always recheck them next year.

The worst case is the valve gets so long you can't shim them down anymore. The the valve needs to be replaced = head off etc

[Strikmabill]

Funny, I thought the valve spring shrunk over time due to pressure between the camshafts and the compression in the cylinders. Will get to it tomorrow. The bike has 16000km so most probably this check has never been done. Should the stock shims all be the same size? And since they must have the thickness marked on them i shouldn't need a dial calipers right? Will report back how it goes. Thanks a lot. Cheers.

[Evilchicken0]

Yes the diameter is the same ... the thickness differs

The wear is due to the valve getting longer not the spring shortening .... although you could check their lengh

[Marty_rillo]

Hi there! this is just like what i have done! I checked the clearances and they were all tight as hell some were in constant contact. so the head came off and i checked the wear on the intake valves and the valves themselves were worn to bits, completely dished every single one, so i have had to replace all the valves on the intake and while im in there have also lapped in all new exhausts valves as well. Quite a costly rebuild though, but the valve seats were all good, only one had a miniscule pit that came out easy with some elbow grease! still to stick the head back on but thats what im doing the end of the week.

[Strikmabill]

Took the camshafts off expecting to find valve shims that looked like coins and I found metal buckets and I think the valves are right under them.



And the camshafts were a real pain to take off, how do i loosen the chain or where can I find the camchain tensioner? And I might have dropped one of the three little metal tubes that have the black bolts going through them in the chain hole... How can I get it out of there? Or it might have fallen in the tubes were the carbs are held, because I'm an idiot and forgot to cover them with a cloth or something.

What do I do now?

[Evilchicken0]

The shims should sit on top of the valves - they're only small and sometimes stick to the underside of the cam follower.
The cam chain tensioner is on the back of the barrels in the middle - you can carefully undo the bolts that hold it in place so you can take the whole part off try not to break the gasket.

What do I do now?

Ummmm ... who's going to tell him ....


Quickly - you use an extenable magnet and a head torch you prod around and hope to hell you find the fuckers or you could get it in a fast moving gear and completely break your engine.

Longer - drain the oil and take the sump off and again look around in it carefully.

[Strikmabill]

I'll take the long road, already have the downpipes off so won't be too hard..
Is it my impression or do shims have a little magnetic centre? And they are 7.48mm in diameter right? A friend will lent me a dial calipers tomorrow to check but shims have 188 and 189 written on some. This means 1.88 and 1.89 mm in thickness?

And if the valves get longer with usage then I should get new shims so the clearance stays at 0,30mm for exhaust and 0,20 for intake so they have 'room to stretch' without needing another check in the nearest future am I right?
Will carry on and report back. Cheers.