how to measure valve clearance

255 to 265 is usually the first range of shims when the motor leaves the factory.

215 (or possibly 275) would be worrisome because that is pretty far out of normal range. By now, 35 years or so later, most 550 motors, that have only had routine maintenance done, will be in the 230 to 250 range. The 550's clearance tends to get smaller with age and wear.

I've never heard of a broken under-bucket shim from normal use on a 550. Since the head is already off, I guess just look for anything suspicious on the valves etc

Maybe a choke flap got caught in that valve for a while, then moved out. That would cause the cam lobe to hammer on the bucket/valve for a little while. Maybe that cracked the shim. Check for nicks in that valve seat and valve.

I'm not sure if money is a big issue for you, but I'd try to get a good, used micrometer on ebay. Condition is everything, though. The old Starretts and Mitutoyos I've gotten from ebay far out-perform the new, cheap ones from Harbor Freight etc. Once you get a good one, you're going to want to measure the shit out of everything.

(Calipers are sometimes not precise enough for shims, if you want to get the real thickness numbers. They are not always exactly as marked. A micrometer is better for shims.)

Or maybe someone put in a 215 where a 275 was needed thus hammering the shim. How do the valves look? I'd put in Viton seals while the head is off.
Steve

Hey guys another question.. It's actually quite a dumb question. Again two manuals, with different specs. Attached are the pictures. Can anyone confirm the proper clearances for a 1984 KZ550 ltd?

The first two agree with each other. I can't read the third too well, but I don't see a valve clearance range in the third photo.


And never mind about the choke flap comment. Your bike does not have them.

I recommend a set of calipers to measure the shims. You can get a set from Harbor Freight for about $20. A micrometer will work as well but is total overkill for such usage. Plus it's difficult to read unless you have a digital version which is more money.

kayodash wrote: As an update, I've got the shims out, all on exhaust side have a 255 In them. Now here's the kicker.. Cylinder 4 intake.. Has a 265.. Cylinder 3 intake I found a broken shim cannot read the size. Cylinder 2 intake..is either 215 or 275.. Can't quite make it out. Cylinder 1 intake looks to be either 275 or 225 I can't make out. Any way of measuring shims?? I tried holding the unknown next to the clearly printed and looked at visible thickness differences but they are close.

Those shims are almost certainly 2.75's. No way a bike with 2.65's and 2.55's is going to have 2.15's unless someone performed a hack valve job and cut the crap out of the seats. Very unlikely.

I've found shims can vary by almost .02mm. That's almost halfway to the next size. The mic lets you measure the center spot where the valve makes actual contact. Rather than the perimeter thickness that a caliper measures.

Splitting hairs on the micrometer vs. caliper. For guys that don't own either, get a caliper. It's far more useful overall.

Nessism wrote: Splitting hairs on the micrometer vs. caliper. For guys that don't own either, get a caliper. It's far more useful overall.

I agree with that for sure.

I had them measured at my local shop the biggest sim I had was a 270

kayodash wrote: I had them measured at my local shop the biggest sim I had was a 270

That's about right for a stock motor from the factory.

What was the smallest, 215?

And a huge rookie mistake, I realized the clearances were in mm I was measuring in inches lol. I've made the conversions but I'm at work so I don't remember what sizes where in what one. So ill have to wait til tonight to get the right sizes. I'm glad I caught it before I got shims I didn't need.

Hey, even Nasa screws that up.

One of the manuals you had shows both.
0.002" is very roughly 0.05mm.

So shims come in .05mm increments which are approximately .002" increments.