Measuring valve clearance

[ptm]

I'm doing a valve adjustment on a '78 GS750EC - 8-valve with shims.

According to the manual you can measure the clearance either when a cam lobe is pointing up perpendicular to the top of the head, or when the lobe is pointing parallel to the top of the head (pointing forward for exhaust or pointing to the rear if it's an intake).

I measured each valve in both positions and only 4 of them (3 exhaust and 1 intake) measured the same in both positions - 1 within spec, 2 too tight and 1 too loose. Of the others, 3 were within spec when pointing to the side and either too loose or too tight when pointing up. The other was within spec when pointing up and too tight when pointing to the side.

My question (finally) is which measurement should I trust?

The bike has 37,000 miles and I have no idea if it has ever had the valves adjusted.

Also, the spec is 0.03 -- 0.08 mm. The smallest feeler gauge I have is 0.04 mm, so when I say too tight, it's really just less than 0.04

Thanks

 

[Anonymous]

shims

shims

Find the right gauge, your wasting your time other wise

 

[KEITH KRAUSE]

I "experimented" once like you did and got different reads too.
I have the factory manual for my '79 1000 and I just follow the procedure to the letter. I always follow Suzuki's word if in doubt. Never had a problem. The way the manual says to do it requires the least amount of turning the crank and is the quickest/easiest way to check. I'm always careful to turn the crank slowly and not have to "start over".
You turn the crank to bring #1 exhaust cam lobe parallel with the head, at this time you check BOTH #1 and #2 exhaust lobes. AT THIS TIME you change shims if necessary and wipe a light coat of the motors oil on the replacement shim before installing. Then rotate the motor 180 degrees and the intake cam lobes of #1 and #2 will be in the correct position to check and change if nesessary. Turn another 180 degrees and check/change the lobes at exhaust #3 and #4. Another 180 and check/change the lobes at intake #3 and #4. Do this only on a motor that's sat overnight. Stone cold. Not just a few hours.
You really need to get a gauge that has .03mm. My gauge is made by RSK. If they're still around, that may help you locate one.
Two tips: If riding the day before doing the clearances, after shutting off the motor, push the forks up and down several times to help more oil drain out of the cover area. It's even better to lean the bike over (be safe) some. This helps drain the oil and the job will be less messy.
If using a stock fiber gasket, apply a very light coat of bearing grease to both sides and it will come off much easier the next time.

 

[ptm]

Yep, I'll get another gauge - hard to imagine what a .03mm blade will be like - that's awfully thin.

The reason I'm approaching the way am is this bike is new to me and I wanted to get a record of all the shims in there, and I don't have a supply of shims so I can't adjust them as I go. I was hoping to go through them all and then either swap some around if I could and/or buy new ones of the size that would (hopefully) make the clearance right.

By the way, I am using a factory manual and it's where I got the info about measuring the clearance when the cam lobe is in either position, but you're right - I wasn't going through their step by step procedures. I'll try that and see what I get.

Thanks for the help.

 

[KEITH KRAUSE]

You can do the "cycle" and write down the clearances and then pull/replace each shim for its size as you go. Then you should know what you have to buy after any swapping. I've done this though, carefully, and still found 1 or 2 clearances "changed" on me after shim changes. Hopefully, all your shims will be installed with the numbers facing down, because they'll wear off if installed facing up. Some shops will trade you shims if you like, others will charge maybe $10. Just don't go to a Kawasaki/Suzuki dealer and get Kawasaki shims by mistake. Kawasaki shims are smaller diameter across (29mm), Suzuki's are 29.5mm.
You can also buy "fat" shims. A fat shim has an "X" after the thickness number. A fat 2.70 for example will actually measure 2.71 up to 2.73mm.
If any of your shims are a "tight" .03mm, always error on the loose side. A .08mm is better than a tight .03mm. Again, this is where the fat shims help a lot.
Valve clearance reads can be funny. After I've set all the clearances, I always do the cycle again and re-check per the manual's procedure.

 

[Poot]

I'm also about to do my clearances......

the manual says clearance should be between .03 and .08 mm....what is the desired clearance? right in the middle at like .05? or right a .03?
I bought this non-magnetic feeler gauge set

http://buy1.snapon.com/catalog/item...D=9522&group_ID=1126&store=canada&dir=catalog


I was planning on putting the two larger sized feelers together , which would give me .03mm.

Will this give me problems??

poot

 

[ptm]

Thanks, Keith. Actually, one of them was in upside down, but it hadn't worn enough to erase the number.


Poot - That feeler gauge won't work - those measurements are in inches. You want .03 mm, which is about .0012 inches.

.0305 mm = .0012 inches

http://buy1.snapon.com/catalog/item...D=9511&group_ID=1122&store=canada&dir=catalog looks like it might work.

In general I believe it is OK to use two smaller blades together to get the thickness you want.

As far as the 'optimum' clearance, I don't think it matters as long as it's within the spec. With the shims (even with the 'fat' X ones) it's near impossible to get an exact clearance. As Keith mentioned, it's better to be a little loose than tight, so closer to .08 is better than closer to .03.

 

[bwringer]

I've found that the aftermarket shims I get from Cycle Recycle II are usually a wee bit fatter than marked, but Suzuki OEM shims are usually dead on (YMMV).

This can be useful if you're trying to "fine tune" clearances so you don't have any right at .03mm.

Or it can drive you nuts if you don't know what's going on. A good micrometer or digital caliper is your friend. Even if you can read the number on the shim, sometimes it's a damn dirty lie. Measure everything, even (especially) new shims.

I have seen clearances that seem too tight just after replacing a shim -- sometimes you have to rotate the engine a few more few times to squeeze more oil out from between the shim and its bucket. Surface tension should hold them in pretty well -- if they're easy to rotate or pop back out, there's probably still too much oil in there.