valve clearence and me

[spaceboy]

Hey all,
I'm in need of some guidance. I checked my clearances today, here's what I found:

Left Exhaust:
<0.03mm clearance
2.62mm shim

Right Exhaust:
<0.03mm clearance
2.7mm shim

Left Intake:
<0.03mm clearance
2.65mm shim

Right Intake:
<0.03mm clearance
2.6mm shim

Bike info: '94 gs500, just under 50000 kms on the clock. I guess the valves have not been adjusted for a while 

All of the buckets spin freely. I was able to fit a .03mm feeler under all of them with a bit of force.
So since all of my valves are out of spec, what would be a good starting point? I'd imagine around 0.05mm of clearance all around would be fine. So what should my respective shim thicknesses be? Or should I get a test shim and go from there?

I also tried swapping two of the shims. The valves that I swapped, then swapped back again to original, wont let me slide a feeler under, like before. And one of the buckets doesn't spin as freely as it did. I cranked the engine over a few times, thinking it was oil under the shims, but that didn't help.

Also, I cranked the engine a bit to move the cam lobes, and one of the lobes moved over a bucket with no shim. No harm done, right?


Thanks again, guys.

[simon79]

Your best bet could be to measure every shim's thickness. So you know if, say, a 2.60 is really 2.60 or has worn out somehow.

Once you're sure about it, you can buy/get the next lower shim size, the factory ones can be odd sizes like your 2.62 but the shims you can buy at dealers come in multiples of 0.05 mm, eg. 2.60, 2.65 etc... (the smallest available being 2.15).

That said, assuming
a. you actually have shims as thick as those you listed, and
b. you have around 0.03 mm of play, (you said you can barely fit a 0.03 blade under there)

a suggestion could be as follows:

Left Exhaust:
<0.03mm clearance
2.62mm shim ---> change to a 2.60 or  a 2.55... on the EX you're better off loose than tight

Right Exhaust:
<0.03mm clearance
2.7mm shim -----> change to a 2.65 or even a 2.60, same as before

Left Intake:
<0.03mm clearance
2.65mm shim-----> change to a 2.60

Right Intake:
<0.03mm clearance
2.6mm shim ----> change to a 2.55

Some set their valves - especially EX - on the loose side of the recommended OEM range (0.03 - 0.08 mm), so as to reduce valve seat wear and improve fuel consumption or whatever. (I have one EX valve at 0.09 myself and decided to leave it like that)
No harm in doing that, except if you like to redline, which increases probability to toss a shim.

[spaceboy]

All of those measurements are using a digital calliper. The indicated shim thicknesses were a little off. Also, I couldn't fit a 0.03mm feeler normally, I had to lightly force it in, so I'm guessing that its around 0.02mm all around.

Any particular reason why all my valves are so tight? Even the intake? Maybe abuse by a previous owner?


Also, back to my OP, why did my clearance disappear after a shim swap? And did I do any harm by cranking the engine with one of the intake shims removed?


Cheers.

[tt_four]

Spin the crankshaft around a couple times. You lost your clearance because a little bit of oil gets under the shim and reduces the clearance, but if you spin it once or twice it should squeeze the oil out and get your clearance back. I'd go down a size on all of them, but 0.03 isn't bad.

[commuterdude]

03 is in spec...your valves are fine....ride ride ride.   Seriously unless you had to cram the gage under there you are good to go.   Check 'em again in 4K.

[spaceboy]

Like I said, its less than 0.03, I had to push the feeler in.

[jp]

I would ride the bike for now, but I would order the shims to have them ready to swap when you check the next time. Unless you're really revving the crap out of your engine, you're better off with the clearance at the high side of the spec.

[spaceboy]

Not going to be riding until April. By then the salt should have been washed off the roads.
I just emailed the dealer asking for shim prices. Should have a reply back tomorrow.

Sometimes I like to rev her a little, but not too much. I guess with that, .04-.05 would be best?


Left Exhaust:
<0.03mm clearance
2.62mm shim ---> change to a 2.60


What would this increase my clearance by? 0.02mm?

[spaceboy]

Local dealership was kind enough to offer to swap shims with me. I'm going over there in a few days.

[jeremy_nash]

be sure that you get the same diameter shims, they arent the standard suzuki size

[black and silver twin]

be sure that you get the same diameter shims, they arent the standard suzuki size

29.5 mm diameter