TOPIC:

Hey all,

Just a small update. I took out the cams, cleaned the buckets and shims, and tightened everything down again. And got different numbers!

I've been using the 180 degree lobe method this whole time, so I also tried the FSM specified method and got some more reasonable numbers, but I'd like them a little more loose I think.

What do you guys think:

- Do my clearances look okay?
- Should I just get smaller shims while I have it open?
- Would torquing the cam caps too tight cause the valve clearance to tighten?

If they currently are set using the FSM method and if they are all at the clearances shown in the FSM column in your spreadsheet, I would leave them alone. They are all within the specified ranges. Further fiddling may lead to stripped cam cap threads.

Keep in mind that as hours are put on the engine the clearances can get smaller OR greater. Mine have varied very slightly in both directions. Any particular valve can get tighter and then looser over time because there are many variables that affect the clearances.

Again, I would definitely leave well enough alone and then measure them again after another 1,000 miles or so to see what, if any, changes have taken place. Assuming everything has been put together and measured correctly I believe you will find that they change very little if at all. Ed

650ed wrote: If they currently are set using the FSM method and if they are all at the clearances shown in the FSM column in your spreadsheet, I would leave them alone. They are all within the specified ranges. Further fiddling may lead to stripped cam cap threads.

Keep in mind that as hours are put on the engine the clearances can get smaller OR greater. Mine have varied very slightly in both directions. Any particular valve can get tighter and then looser over time because there are many variables that affect the clearances.

Again, I would definitely leave well enough alone and then measure them again after another 1,000 miles or so to see what, if any, changes have taken place. Assuming everything has been put together and measured correctly I believe you will find that they change very little if at all. Ed

Thanks Ed! Yes, the FSM method is in green. It's actually much easier to check the clearances that way than eyeballing if the lobe is exactly 180 degrees away from the bucket.

I can finally move on to getting the carbs on! One step closer...

I'm on a '78 KZ650 C2 and have the factory service manual and the Clymers—I checked the valve clearances using both the factory method (align T marks, check two shims at a time) and the other method (visually align cam lobes pointing 180º away from shims) and all but two valves came out with the same numbers—and even those two were still within a ~0.01mm difference) so I'm going with the factory method based on feedback listed here (i.e. cam cap wear, valve spring pressure skewing results, etc.).

Here are my measured and calculated numbers (using factory service method; my feeler gauges have millimetre increments of 0.038, 0.051, 0.063, 0.076):

Cylinder (1-4 exhaust, 5–8 Inlet) / Measured Gap / Current Shim / Needed Shim
1 / 0.063 / 260 / 250
2 / 0.063 / 260 / 250
3 / <0.038 / 265 / 250
4 / 0.063 / 255 / 245
5 / 0.063 / 265 / 255
6 / 0.076 / 255 / 245
7 / 0.051 / 265 / 255
8 / 0.051 / 270 / 260

So if I calculated this correctly and swap some shims around, then what I need to buy are:
245mm shim x 2
250mm shim x 3

Posting this for posterity 'cause this thread seems the best I've found so far…and in case anyone wants to check my math / chart reading abilities / faith in a just and fair cosmos. Note this is my first time checking valve clearances; bike has 35,000km and I don't really know the previous owner maintenance history.

jeffwerner wrote: I'm on a '78 KZ650 C2 and have the factory service manual and the Clymers—I checked the valve clearances using both the factory method (align T marks, check two shims at a time) and the other method (visually align cam lobes pointing 180º away from shims) and all but two valves came out with the same numbers—and even those two were still within a ~0.01mm difference) so I'm going with the factory method based on feedback listed here (i.e. cam cap wear, valve spring pressure skewing results, etc.).

Here are my measured and calculated numbers (using factory service method; my feeler gauges have millimetre increments of 0.038, 0.051, 0.063, 0.076):

Cylinder (1-4 exhaust, 5–8 Inlet) / Measured Gap / Current Shim / Needed Shim
1 / 0.063 / 260 / 250
2 / 0.063 / 260 / 250
3 / <0.038 / 265 / 250
4 / 0.063 / 255 / 245
5 / 0.063 / 265 / 255
6 / 0.076 / 255 / 245
7 / 0.051 / 265 / 255
8 / 0.051 / 270 / 260

So if I calculated this correctly and swap some shims around, then what I need to buy are:
245mm shim x 2
250mm shim x 3

Posting this for posterity 'cause this thread seems the best I've found so far…and in case anyone wants to check my math / chart reading abilities / faith in a just and fair cosmos. Note this is my first time checking valve clearances; bike has 35,000km and I don't really know the previous owner maintenance history.

Good job. I found there to be a larger difference between the two measurement methods but regardless, you are on the right track.

When positioning the cams I don't even look at the timing marks. I simply point E1 lobe forward and then check E1 and E2. Same thing for E4 pointing forward and then checking E4 and E3. With the Intake cams, point I1 at 90 degrees and then check I1 and I2, and so forth... It's very simple once you realize all you need to remember is two cam positions. The method described is detailed in the Suzuki GS service manuals. The GS engines are a copy of the KZ so it's all in the family.

Nessism wrote: The method described is detailed in the Suzuki GS service manuals. The GS engines are a copy of the KZ so it's all in the family.

Good to know as I just picked up an '82 GS650G that I'll be going over next month.