Valve Clearance MAX?

[ivany]

Hey,

So I'm doing my valves. My intakes measure in right about 0.102mm which is fine. My exhausts are less than 0.038mm but spin freely. Should I knock the exhausts up by 0.05mm, or 0.1mm instead to give myself room to wear?

Thanks!

[gregvhen]

what do you mean spin freely?

[gsJack]

I assume you mean the exhaust buckets spin free.  I'd increase the gaps by 0.1 mm if they are less than .038 mm now.  I set my exhausts to .004-.005" gap now when changing shims.  Your bike, your choice.

http://img.photobucket.com/albums/v443/jcp8832/valveclearances.jpg

[ivany]

I assume you mean the exhaust buckets spin free.  I'd increase the gaps by 0.1 mm if they are less than .038 mm now.  I set my exhausts to .004-.005" gap now when changing shims.  Your bike, your choice.

http://img.photobucket.com/albums/v443/jcp8832/valveclearances.jpg

This is what I was leaning towards. Thanks!

The other odd thing is the wear. I last did the valves at 11,000 and change. I set the exhausts to about 0.9 each, and the intakes to 0.1-ish. Now I'm at 17,000 and change. The intakes have hardly changed but the exhausts are all the way down below 0.038. What's up?

[black and silver twin]

Exhaust valves get much hotter than intake valves and are more prone to stretching/recession

[gsJack]

I've found the intake valve gaps rarely change thru the life of the bike but the exhaust valves commonly recede into the seats and this is much greater if they are run at the .001" min clearance.  The GS valve set specs are much too tight in my opinion, the exhaust valves need more cooling seat time as provided by wider gaps.  I ran one too tight, min spec, on my 97 GS for a long time and ended up with a 215 min shim thickness at 80k miles with no adjustment left.  

After one exhaust valve ran on the tight side on my 02 GS for a while I decided to set the exhaust gaps wider to a .004" or .005" gap and it worked, took two adjustments to get there but it's held at .004" for another 40k miles since.  Linked my valve check record above so you could see that.  Expect to go over 100k miles on the 02 GS now still using mid size valve shims.

I'd suggest you set your exhaust valves to the wide side now and check them again in a few thousand miles and see how they are going.  If your redlining your engine all day long you might want to stay closer to the .003" max Suzi spec, I rarely if ever go over 9k rpm on my completely stock 02 GS.  No need to go further with an engine that reaches peak HP at 8500 rpm.