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Easy Peazy Valve Shim Calculator


yamagrl

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...while adjusting Big Red's valves today I made discovery. Probly nuthin' major but it hit me like a "Profound Revelation"!

 

...if you "Think Metric" it's simple math. No need for an Excel spreadsheet or shim table. After a few times it just comes to ya.

 

...of course it works the same for the intake and exhaust valves and whether the valve is too tight or too loose.

 

First Gen Specs

Intake .11-.15 mm (.004-.006 in) ideal/average .13 mm (.005 in)

Exhaust .16-.20 mm (.006-.008 in) ideal/average .18 mm (.007 in)

 

THINK METRIC

Measured Clearance

+ Existing Shim

= Existing Total

- Ideal/Average clearance

= Ideal new shim size.

 

 

Example:

exhaust valve measuring .13 mm clearance (a bit tight) with an existing installed shim 2.80 mm

 

Measured Clearance .13 mm

+ Existing Shim 2.80 mm

= Existing Total 2.93 mm

- Ideal/Avg Clearance .18 mm

= Ideal new shim size 2.75 mm

 

We all know that numbers rarely work out perfectly like the above example. And we do not always have the exact shim we might need. So I'll work out another example:

 

Exhaust valve measuring .13 mm clearance (a bit tight) with an existing installed shim 2.68 mm

Measured Clearance .13 mm

+ Existing Shim 2.68 mm

= Existing Total 2.81 mm

- Ideal/Avg Clearance .18 mm

= Ideal new shim size 2.63 mm Your choice may be 2.60 rendering .21 mm (slightly over the loose end of specs)

2.65 rendering ..16 mm (limit on the tight end of specs)

I think slightly loose might be better. It will wear into the specs, whereas max tight will soon wear out of the specs.

 

And ya probly wanna verify things with a micrometer.

 

 

"Close enough for government work"

Measured with a micrometer...Marked with a grease pencil... and cut with a chain saw!

 

Attached is a PDF Worksheet. Print it out.

 

Heather

 

[ATTACH]105064[/ATTACH]

 

[ATTACH=CONFIG]105065[/ATTACH]

 

Easy Peazy Valve Calculation Sheet.pdf

Easy Peazy Valve calc.jpg

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