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Discussion Starter #1
I have an exhaust valve clearance way too tight (21/27). Its shim size was no longer visible so I brought it to a shop and they measured it to 1.63. If everything is correct it means I need a 1.00 shim to bring it back to spec, but there are no shims that small! Going to get a micrometer and recheck everything myself but what sorts of valve problems am I looking at if the smallest available shim (1.2) will not bring it back to spec??
 

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I think you're making an error on your sizes D.S. What was your measured valve clearance and what is spec for your bike? I take it 21/27 is the desired clearance spec range. You should only be changing the shim from a 1.63 down to maybe a 1.60 or something like that. Not a 1.0 mm as you mention. That would be way too much a probably why it's not available.
 

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I have an exhaust valve clearance way too tight (21/27). Its shim size was no longer visible so I brought it to a shop and they measured it to 1.63. If everything is correct it means I need a 1.00 shim to bring it back to spec, but there are no shims that small! Going to get a micrometer and recheck everything myself but what sorts of valve problems am I looking at if the smallest available shim (1.2) will not bring it back to spec??
You can very carefully grind a shim to the required size.
I recommend grinding the face that has the size marked so nobody accidently uses it without measuring it.
I would be checking why you need such a thin shim though. Have the valve seats been re-cut?
 

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I think you're making an error on your sizes D.S. What was your measured valve clearance and what is spec for your bike? I take it 21/27 is the desired clearance spec range. You should only be changing the shim from a 1.63 down to maybe a 1.60 or something like that. Not a 1.0 mm as you mention. That would be way too much a probably why it's not available.
Good point Den.
I didn't think to check the calculation but I don't know what the 21/27 means either.
By "way too tight" what exactly is your measured clearance?
They should be 0.13-0.19mm IN and 0.24-0.30mm EX.
If you're looking for a 0.6mm shim reduction then the valve isn't even closing and it has no clearance.
 

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Discussion Starter #5
Ok I wasn't very clear..

I used feeler gauges in mm. On one of the exhaust valves of cyl #2 (specs for exh valves are 0.270mm +- .03mm) I could get a .22mm gauge in easilly but not a 0.20, so I estimate clearance to 0.21mm. The '21/27' is measured clearance vs desired clearance.

So if the clearance is 0.21mm and the existing shim is 1.63

a=(0.21-0.27)+1.63
a=1.57... ehm.. ok I'm officially retarded. Nevermind, carry on.

Denzee, thanks for noticing the obvious, sometimes one needs an extra set of brains..
 

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Ok I wasn't very clear..

I used feeler gauges in mm. On one of the exhaust valves of cyl #2 (specs for exh valves are 0.270mm +- .03mm) I could get a .22mm gauge in easilly but not a 0.20, so I estimate clearance to 0.21mm. The '21/27' is measured clearance vs desired clearance.

So if the clearance is 0.21mm and the existing shim is 1.63

a=(0.21-0.27)+1.63
a=1.57... ehm.. ok I'm officially retarded. Nevermind, carry on.

Thanks for seeing the obvious, sometimes one needs an extra set of brains..
You add feeler gauges together for measuring so you should be able to measure to within 0.05mm and always check your feeler gauges with a mic. I actually keep my feeler gauges in my mic box so I can't use them without the mic :)
 

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Discussion Starter #8
You add feeler gauges together for measuring so you should be able to measure to within 0.05mm and always check your feeler gauges with a mic. I actually keep my feeler gauges in my mic box so I can't use them without the mic :)
Good point, I actually used borrowed gauges because I couldn't find any in smaller increments than 0.25, 0.30 etc). His gauges were 0,20-0,22-0,24 etc. Will try and find a good set and a micrometer. Oh, and a bigger toolbox, it's been swelling at an exponential rate ever since I started on this bike..
 

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Good point, I actually used borrowed gauges because I couldn't find any in smaller increments than 0.25, 0.30 etc). His gauges were 0,20-0,22-0,24 etc. Will try and find a good set and a micrometer. Oh, and a bigger toolbox, it's been swelling at an exponential rate ever since I started on this bike..
It doesn't take long until it becomes far easier to move the vehicle to your tools than drag your tools to your vehicle, at which point you no longer have a toolbox, you have a workshop :)
 

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Discussion Starter #10
It doesn't take long until it becomes far easier to move the vehicle to your tools than drag your tools to your vehicle, at which point you no longer have a toolbox, you have a workshop :)
Haha.. sounds like a plan to me! :thumb:
 
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