Hi everyone,

So today I decided to check my valve clearances and got some good numbers for the intake, .05 and .06mm but for the exhaust valves i got .09mm for both. I know that there should be between .03mm-.08mm clearance but is leaving the exhaust at .09mm bad? It should be getting smaller as time goes on right? I think maybe the PO but shims that were slightly smaller in order to avoid doing too much valve work.

If i were to change them I could only go up .05mm right? which would leave me at .04mm and really close to the tight end.

Quote from: Darkbluestar on June 10, 2011, 04:01:10 PM
Hi everyone,

So today I decided to check my valve clearances and got some good numbers for the intake, .05 and .06mm but for the exhaust valves i got .09mm for both. I know that there should be between .03mm-.08mm clearance but is leaving the exhaust at .09mm bad? It should be getting smaller as time goes on right? I think maybe the PO but shims that were slightly smaller in order to avoid doing too much valve work.

If i were to change them I could only go up .05mm right? which would leave me at .04mm and really close to the tight end.

Leave 'em.......conventional wisdom is slightly wide is better than slightly tight........a little "loose" and the valve will stay closed a little longer  better heat transfer and little to no chance of burning a valve...

Cookie

A few of us are running .08-.13 clearance on the exhaust, with good results. Leave em.

Quote from: burning1 on June 10, 2011, 05:22:46 PM
A few of us are running .08-.13 clearance on the exhaust, with good results. Leave em.

Wow, wish I knew you could set the clearances as high as .13 when I was adjusting my valves a couple weeks ago. I had read that a bit above spec can be good for engine longevity, but since my within-spec exhaust clearances turned out to be .06 and .07, I figured switching to .11 and .12 would be too far above spec. Next time I'll try the wider clearances.

Thanks everyone! I'll leave them in.

Sorry to resurrect a month-old thread, but I have a similar situation with my GS.  My exhaust valves both show about a .115 clearance, one of my intake valves has no clearance (was running a 275; thickness gauge reads it a 271, so going to order a 265 and 260 to be safe.)  The other intake is about .07, so I am ok there.

What does having the exhaust valves above spec do precisely?

How does having an intake valve with no or possibly less than no clearance affect the behavior of the engine?

Thank you in advance for your assistance.

The GS500 exhaust valves will recede into the seats over time if they are run on the tight side of the Suzuki tolerances for too long, they run too hot that way.  Giving them more clearance will provide more cooling seat time allowing more heat transfer to the seat and head and extend the exhaust valve life.

I left one of my 97 GS exhaust valves on the tight side for most of it's first 40k miles and it required repeated shim changes after that until it was down to a minimum 215 shim before 80k miles.  On my 02 GS one exhaust valve was on the tight side for most of it's first 40k miles also so when it needed smaller shims twice in a row like the 97 had I bumped it up to .005" (.13mm) and stopped the valve burning process and now the 02 GS is running mid size shims at 86k miles and I expect it to go 100k without further valve checks and shim changes.

If your valves are actually too tight without any clearance it will run rough on cold startup due to compression loss on that cylinder.  But unless it's way too tight the valve clearance will increase as the engine heats up and it will smooth out as compression is restored.  I found intake valves rarely if ever needed any shim changes since they run way cooler.

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