450F How to determine Valve Shim replacement if current gap is .000

thousandbuckle

thousandbuckle

Hello all, I have a 2002 Honda CRF450R that I am trying to adjust the valves on. This is my first time adjusting a bucket valve system and need some advice.

When I measure the gap on both of the Intake valves the smallest feeler gauge I have .003 will not fit. If I am unable to determine what the current gap is how do I figure out the new shim size. I am guessing the gap is between .002 and .000. I have done alot of reading but unable to figure out how to figure it out if there is a zero gap. I want to do this myself instead of taking to a shop to save the money I don't have.

Your help is greatly appreciated.
 
James

James

Staff member
thousandbuckle:
Hello all, I have a 2002 Honda CRF450R that I am trying to adjust the valves on. This is my first time adjusting a bucket valve system and need some advice.

When I measure the gap on both of the Intake valves the smallest feeler gauge I have .003 will not fit. If I am unable to determine what the current gap is how do I figure out the new shim size. I am guessing the gap is between .002 and .000. I have done alot of reading but unable to figure out how to figure it out if there is a zero gap. I want to do this myself instead of taking to a shop to save the money I don't have.

Your help is greatly appreciated.
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Do you have a shim kit or will you be ordering shims?

If you have a shim kit I'd start from a .002 gap and then remeasure after it's been adjusted. Otherwise buy shims for .002 & .001 gaps (they're cheap).

Also here are two How-To's that might help you:
https://www.dirtbikeaddicts.com/content/threads/checking-valve-clearances-2005-kx250f-rmz250.4199/
https://www.dirtbikeaddicts.com/content/threads/adjusting-valve-clearances-2005-kx250f-rmz250.4214/
 
cleonard

cleonard

If it's truly gone to 0.000 then it might be time to remove the head for rework. If it is not quite zeroed out then guess what shim you need, install it, and take another measurement.
 
SRAD97750

SRAD97750

Moderator
Staff member
You must pull the shim either way. :noidea:
The size or some number will be printed on it. That number correlates with the honda shim chart.
If not, use a micrometer, or vernier calipers.
Once you know what size is installed, subtract the specified spec from that measured size and install the nearest shim.

EXAMPLE: if you find a 3.000mm shim and you need a .150 gap (made up spec) then you should purchase the shim nearest 2.850mm.
73 different thickness shims are available from the thinnest 1.200 mm thickness shim to the thickness 3.000 mm thickness shim in intervals of 0.025mm.

Another way is to use the honda calculator.
http://crfsonly.com/calculators/crf250-valve-shim-calc.php

-BIG DAN:thumb:
 
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