Gs450EX valve adjustment issues

[Guest]

Hello, I'm new to the forum and have been scouring it trying to find the solution to the problem I'm having, with no luck. So my issue is with valve clearance... I have a 1981 suzuki gs450EX that has 16,000 miles on it so I figured it was past due for valve adjustment. Cracked her open, checked the clearance of each valve, positioning lobe perpendicular as described in the manual. My issue is that on a few valves my. 0015 feeler gauge won't fit(so they are way too tight. They have 2.60 factory shims currently. So I purchased some 2.55 and 2.50 shims. If I replace the factory 2.60 shim with a 2.55 then for some reason I can fit a. O5 feeler gauge in between the lobe and shim. Which is WAY beyond spec. I put a micrometer on the new and the old shims to verify that they were indeed the sizes that are printed. I just can't figure this out. Am I doing something wrong? Haha

[tom203]

Spec calls for .001 to .003 INCH clearance.. But I aim for .002 to .004 myself (since it wears tighter). If you put 2.55mm in where you had a 2.60mm ,you increased clearance by .002 INCH. After you switched shims, did you rotate the cams one revolution and recheck? Was everthing clean?
PS : Never rotate cams unless a a shim is in place everywhere!

[Gs450EX]

I did rotate several times after switching shims then checked clearance again. It's strange that before swapping the 2.60 mm shim I get a clearance of. 0015in.(.038mm won't fit) after installing 2.55mm shim I get a clearance of. 005in. (. 127mm) I reinstalled old shim rechecked clearance again, it was the same as my original measurement. I've switched them back and forth several times and get the same result each time. I'm confused as to why I'm getting such a large difference

[John Park]

Maybe it's your feeler gauges; I've had some with a burr on the edge from the stamping process that can make them hard to insert. You may have more clearance with the original shims than you are measuring. The thinner sizes seem to not punch out as cleanly. I'd also measure the feeler gauge and sometimes you get two stuck together with rust.

[Gs450EX]

I checked feeler gauges for burs and checked their thickness with calipers and a micrometer before I started. Also verified new shim thickness before I began. All were good. Brand new feeler gauges, no rust, no burrs, accurately manufactured. I'm stumped

[tom203]

Yes, seems odd, but if you put in .002 inch smaller shims, you are safe. If you use new cam cover gasket, coat it with oil - this way, it will come off easy and be reusable when you recheck the clearances. Run bike for a while and when your curiosity gets too much, check clearances again!

Remember that cover bolts are torqued really low... like 7 ft-lbs. Most 3/8 and 1/2 inch torque wrenches don't work at this level.

[John Park]

Are they Suzuki shims? There are some 29mm diameter shims around that look similar but may fit the bucket differently. The Suzuki ones are 29.5mm, as I recall. I've never used the 29mm ones, and wouldn't think it's a good idea, even though I've pulled them out of running motors. Well, not While they're running….

[Gs450EX]

I measured the diameter as well. They are 29.5mm shims.