Valve Shim Help.

[GreenoBeano]

I was checking valves today using BaltimoreGS youtube guide. And my smallest feeler gauge of .0015 does not fit under any valve. Since this is my first time doing this, i'm assuming they need to slide all the way under so you can see it on the other side. I get about 1/2 way before it stops completely, pushing any causes the feeler gauge to buckle.

So without being able to get a feeler gauge under it, how do i calculate the shims i need?
the intake shims I could still read the number of 2.60. the exhaust i could not read anything on them, in fact they were so tight i could hardly rotate the bucket to get them out.

any help mucho appreciated.
thanks!

[HPP8140]

Use a dial caliper to get more precise measurement of the shim and then start by dropping down two sizes to get a measurement, if that tight

[SK Racing]

Can someone please confirm what diameter these shims are? Online I found 9.48mm, but that seems rather small.

In this thread, Kerry suggests that it should be a larger diameter. Something like 29.5mm.

[Bluesmudge]

29.5mm sounds familiar. If you buy shims from a Suzuki dealer or website from the GS500 parts fiche then you know you are getting the right size.

The GS500 uses the same shims used in all the Suzuki GS bikes. So, you can buy used shims for a GS1000 or GS850, etc off eBay. That's what I do to stock up on lots of sizes because the 8 valve engines come with 8 shims and it's not a part most people buy so they are much cheaper buying lots on ebay than buying new. Lots of times they come with the buckets, but I just toss those in the recycling. Usually, shims don't wear out but you should check any used shims you buy with a caliper to double check. Plus, sometimes buying shims from salvaged bikes you get the x and + sized shims that only come from the factory, so you can end up with, for example, a 2.62 or 2.67 shim which can be helpful for those times when a .05 jump is too much. Doing this I've amassed a set of all the shims I could ever need (3 or 4 of each size between 2.30 and 2.80) for my GS500 and GS1000 and I probably spent less than $100 total. Now I never have to worry about shims when I go to do a valve check...I know I have it in stock already. The GS1000 uses a lot of shims when you have to change 8 of them! If I only had the GS500 I wouldn't need so many of each size.

Going back to the original question. You should get a set of metric feeler gauges. Cyclegear should have them or you can get them cheap off eBay.  Why? Because .0015 inches is .038 mm which is still within the Suzuki specification. So your feeler gauge might not fit, but if you had a .03 mm feeler gauge maybe that would fit and you would actually be within spec. And yes, the feeler gauge should go all the way through under cam lobe. You will know its the size of the clearance when it drags just a little bit but still goes all the way through. Most metric feeler gauge sets go down to .02 mm so you know for sure if you need to change the shim. Its worth spending the $10 or $15 to get the right set of feeler gauges. Then stock up on the shim sizes that are smaller than your existing shims so you don't have to waste time ordering them when you do the valve checks.  My valve check kit is the Motion Pro tool, a pair of tweezers, a digital caliper, and a couple film canisters full of shims of various thickness. The shims fit perfectly in a plastic 35mm photographic film container, and you can put a little bit of oil in there and but the air tight lid on so the shims never get rusty in storage.

[GreenoBeano]

Thank you for the very thoughtful message Blue.
I called my local Suzuki dealership right after I posted this, and talked to a tech.
He recommended going down 2 sizes (250) and then checking again to see if I'm in spec.
He gave a part number of 12892-45000-250. I ordered them from partzilla, should see them later this week.
I'll order myself a set of Metric feeler gauges, and will report back once I have the shims!
thanks,

[SK Racing]

29.5mm sounds familiar. If you buy shims from a Suzuki dealer or website from the GS500 parts fiche then you know you are getting the right size.

Thank you.

I'm familiar with doing shims because I've been driving Alfa Romeo's since the early 70's and I worked on my own cars for many years.