Shim Calculation

[Bubbleheadsh]

Evening all, i would really appreciate some advice from those in the know.

Today i finally got round to checking the valve clearances on my 2003 ST1300, 91k miles. I'm not sure if they have been checked before so needed doing.

All were fine with the exception of both exhaust valves on Cylinder 2
Both measured .20mm ( Tolerance being .25+/- .003mm) So .002mm below tolerance..

Shims fitted had 155 stamped on them.

So, with the calculation on the worksheet:

a= b-c+d

a=new shim thickness
b=recorded valve clearance ( .20mm)
c=specified valve clearance ( .25mm)
d= old shim thickness ( 155)

Is this correct:
.20 - .25 + 1.55 = 1.5

New shim 1.50 / (150 stamped) ?

Could someone advise what the new shim number should be please?

Thanks

 

[dwalby]

yeah, 1.50 sounds right to me. You were tight by 0.05mm initially, so you want a shim that's 0.05mm less thick than the original.

BTW, are you measuring with metric feeler gauges? If so, what's the range of thicknesses you have available for this job?

When measuring with feeler gauges in inches, every 0.001" is one shim size, which is 0.025mm, so its pretty easy to do that math in your head. Whenever I've seen metric feeler gauges they were never in increments of 0.01mm so the range specified by Honda of 0.22mm to 0.28mm was actually more suited to the inch based gauges anyway. If your gauges are in 0.05mm increments for example, that's 0.002" so you'd get twice the resolution by using inch based gauges.

 

[970mike]

You sound like you are on the right track, make sure you measure the shim as they are not always what is stamped on it.

 

[Bubbleheadsh]

You sound like you are on the right track, make sure you measure the shim as they are not always what is stamped on it.

Will do, hadn't considered that! thanks

 

[Bubbleheadsh]

yeah, 1.50 sounds right to me. You were tight by 0.05mm initially, so you want a shim that's 0.05mm less thick than the original.

BTW, are you measuring with metric feeler gauges? If so, what's the range of thicknesses you have available for this job?

When measuring with feeler gauges in inches, every 0.001" is one shim size, which is 0.025mm, so its pretty easy to do that math in your head. Whenever I've seen metric feeler gauges they were never in increments of 0.01mm so the range specified by Honda of 0.22mm to 0.28mm was actually more suited to the inch based gauges anyway. If your gauges are in 0.05mm increments for example, that's 0.002" so you'd get twice the resolution by using inch based gauges.

Hi, Thanks for your reply!

Yes, using metric gauges.. I did have two sets with different increments which did give me a pretty good option to match up a different measurements so fairly happy with what it was measured at. Just wanted to check that i was reading it right and the answer we came up with was correct.

Funnily enough, my dad was helping, who had done his a few years ago, with imperial feeler gauges and did say it was easier to work out, unfortunately, my brain doesn't work with imperial..