Zero valve clearance problem

[IL_Rider]

maybe its cheaper just to buy a 'new' head and transfer all the hardware over..   Anyone happen to know of a place in Los Angeles where I could get new valve seats done?  It seems that everyone agrees that this is the underlying issue causing the lack of valve clearance.  Also, what does it cost for that kind of work?

[werase643]

Ian,
It's a race engine...therefore it should have a shorter service life...also the valves should be checked every 2-3 race weekends

if it was a street engine....what is the shorter service life...10k....15k..?before the valves mushroom

another option is to get 1-2 mm bigger valves and have a valve job done

and check the valve clearance before you reassemble the engine  just reassemble the head with cams

[IL_Rider]

Maybe I'm confused, but since I am short of clearance, dont I actually want smaller valves rather than bigger  ones?  Or does bigger mean something different to longer?  I just spent $200 on having the head reworked and two new exhaust valves installed  so I'm kind of surprised at the current situation.

The valve situation arose because I took the bike to the track after buying it without checking the clearances myself.  My mistake for trusting other people to do things right, should have checked them myself and then the current situation would have been caught earlier.

[werase643]

bigger valve will require the seats to be cut....wider...therefore the valve should be sticking out a bit further...therefore better clearance

[werase643]

check out kibblewhite...valves.... they make them in SS and could cut them 0.010 or what ever shorter so you have plenty of room for shims
they are pretty cheap...15-20 bucks each   i've heard 12.....

[The Buddha]

They make a GS500 kit.
blackdiamondvalves.com
Cool.
Srinath.

[gsJack]

I mentioned before that my old 97 GS had the original intake valve shims in it and adequate clearance at 80k miles.  And yes sledge, considerable exhaust valve seat regression does occur on the GS's.  At the same 80k miles, one exhaust valve had the min 215 shim and the other was close to it.

IL_Rider, since the intake valves are to spec now I'd leave them alone if they were mine and I would consider grinding the ends off of the exhaust valves. I really wouldn't expect any mushrooming or significant wear at the ends of the ground off exhaust valves, they seem to be as hard as rocks thru and thru. There seems to be a little over a millimeter sticking out of the valve keepers so I'd probably grind off a little more than half of that.  Should increase required shim thickness from 1.65 to 2.15 or so.  The bucket has a raised pad inside it that contacs the end of the valve.



My 02 GS had a sticking exhaust valve bucket and with approx 21.5k miles on it, I cranked the engine one very cold morning and it stopped with a bang!  That exhaust valve stuck open and it's head was broken off.  Fortunately it crashed at cranking speed and only broke off the one valve head.  That very hard exhaust valve nicked the edge of the intake valve and grooved the piston top a bit but the exhaust valve head itself was not marked, it just broke off like a full hardened thru valve stem would.



I just replaced the broken valve and the tight bucket with parts davipu sent me and also lapped in both valves to make sure the intake valve wasn't bent a bit.  Only had to buy the head and cyl base gaskets and she's been running like new for two more seasons with about 42k miles on it now and I expect it to go another 40k like the 97 did.  

If a reasonable fix couldn't be made, I think buying a used head assy would be less expensive around here than getting someone to replace valve seats.

I don't see why one side of the case hardened shims couldn't be ground off and placed down in the bucket recess with the remaining hard side up to take the cam wear.  I was considering doing that on the 97 next time but it was totaled, retired, and replaced with the 02 before further valve adjustment was required.

[sledge]

All valid points Gents.............here is a good site all about valves. Lots of info, the failures section is very good.

http://www.gsvalves.co.uk/surface_treatments1.htm

[IL_Rider]

So if I want to grind the tips on the valves, is this a job for a professional?  I guess that surface has to be perfectly flat and perpendicular to the valve stem in order to minimize stresses in the valve stem?  Looks like it would be very easy with the right tool, but not one that I have!

[werase643]

calculate your clearance
then calculate the amt to grind off to get you back into the middle of the valve shim range
then go to a machine shop and have the tip ground down

[IL_Rider]

job done, clearance achieved - thanks for all the help!  Just waiting on the new shims now.  Just for future reference, I had 30 thousandths ground off the tips and that was as close as you would want to go.  I think we calculated the original clearance gap at 65 thousandths (1.65mm) or so.  I suppose this might help someone figure out how much to grind off their valve tips if they get into the same situation.

[ducati_nolan]

Nice, back on the road finally  ........almost
Good luck