how do I calculate shim size needed?

78 kz650. I'm trying to calculate the shims I need the book says take the current clearance minus the suggested clearance (0.15) then take that answer and add the existing shim number and that will give me the new shim needed. It's giving me the same shim number I currently have under the bucket.

blink543 wrote: 78 kz650. I'm trying to calculate the shims I need the book says take the current clearance minus the suggested clearance (0.15) then take that answer and add the existing shim number and that will give me the new shim needed. It's giving me the same shim number I currently have under the bucket.

Not sure about the 650 but with the 900s-KZ1000s... you read the number stamped on the existing shim, and use the next number shim smaller for a decrease in thickness of about .002"/.05mm. The next number bigger is also +.002"/.050mm.
So, with a really tight shim gap and you measured at say, .001"/.025mm... you might pull the shim and read that it says 240, and go buy a #235 which would open your gap an additional .002"/,050mm or to about .003"/,075mm.... where buying a #230 shim would give you a .005"/.125mm gap.
You'd go the other way... up in numbers (245, 250 etc).. in shim numbers if the gap was large and your were tightening it up....
.15? If that is in mm.... it is about .006".
So are they saying the lash needs to be about .006"/.15mm?

The shim over bucket "shim thicknesses" vary by .002"/0.05mm for each number... up and down.
You'd think that would be the same with yours.

If the measured gap is too small, subtract the difference from the current shim. If the measured gap is too large, add the difference to the present shim.

P.s. Your math is flawed. If you add .15 to your current shim, it cannot equal the current shim. If your current shim is 230, which is really 2.30, and you add .15, you would need a 245 shim. That would make the gap .15 SMALLER.

missionkz wrote:

blink543 wrote: 78 kz650. I'm trying to calculate the shims I need the book says take the current clearance minus the suggested clearance (0.15) then take that answer and add the existing shim number and that will give me the new shim needed. It's giving me the same shim number I currently have under the bucket.

Not sure about the 650 but with the 900s-KZ1000s... you read the number stamped on the existing shim, and use the next number shim smaller for a decrease in thickness of about .002"/.05mm. The next number bigger is also +.002"/.050mm.
So, with a really tight shim gap and you measured at say, .001"/.025mm... you might pull the shim and read that it says 240, and go buy a #235 which would open your gap an additional .002"/,050mm or to about .003"/,075mm.... where buying a #230 shim would give you a .005"/.125mm gap.
You'd go the other way... up in numbers (245, 250 etc).. in shim numbers if the gap was large and your were tightening it up....
.15? If that is in mm.... it is about .006".
So are they saying the lash needs to be about .006"/.15mm?

The shim over bucket "shim thicknesses" vary by .002"/0.05mm for each number... up and down.
You'd think that would be the same with yours.

Good grief! :blink: Just use the Valve Adjustment Chart in the manual. Ed

The number 3 intake measures .203. You said your goal is .15. That means the gap is .053 too big. If I read your chart correctly, the shim is 2.65. Add 2.65 and .053 and you need a 318 shim. Since they come in .05 increments, a 315 should be ideal.

TexasKZ wrote: The number 3 intake measures .203. You said your goal is .15. That means the gap is .053 too big. If I read your chart correctly, the shim is 2.65. Add 2.65 and .053 and you need a 318 shim. Since they come in .05 increments, a 315 should be ideal.

???
2.65 +.053 = #2.70.... not 315! LOL!

However... 650ed's comment is right on! The FSM chart is really easy to understand!

There is an excel spreed sheet located at this link for determining what shim you need. It is specially for the (K)Z650 s. Hope it helps you.

tips.kz650.info/index.php

Ok so you need a 260 for #1 exhaust .......... and a 270 for #2 and #4 Exhaust

And a 255 for #2 intake......... and a 255 for #3 Intake............... check out the Valve clearance thread you made too for assembly tips.

Maybe someone else could add to that too so you don't mess up something.

See that? Proof that folks should do their own math! Doh!
I think that chart was deemed unimportant by Clymer and was omitted from their lovely little book.

missionkz wrote:

TexasKZ wrote: The number 3 intake measures .203. You said your goal is .15. That means the gap is .053 too big. If I read your chart correctly, the shim is 2.65. Add 2.65 and .053 and you need a 318 shim. Since they come in .05 increments, a 315 should be ideal.

???
2.65 +.053 = #2.70.... not 315! LOL!

However... 650ed's comment is right on! The FSM chart is really easy to understand!

Yup, t he chart is very simple. So is the math as long as you don't let goobers like me randomly move the decimals around....