selecting the proper valve shim

[Papakeith]

This is for my 04 CFR450

It had been some time since I had checked the valve clearance on my bike. It was hard starting it on the last ride so I figured I'd better get to it. Well, sure enough, the intake valves were out of spec. Would you guys check my math and help me make sure I'm doing my calculations correctly so that I get the right replacement shims?

Specified valve clearance:
Intake .006 +_.001 .16mm
Exhaust .011 +- .001 .28mm

The exhaust valves were in spec so I'll get right to the intake valves. Here are the numbers I came up with

Left Intake
<.002 or somewhere between .0254mm and zero. I don't have any feeler gauges thinner than .002
current shim size is 1.65

Right Intake
.003 current shim size 1.75 .0762mm

Doing the math: A= (B-C) + D
Where A = new shim thickness
B= recorded valve clearance
C= Specified valve clearance
D= Old shim thickness

Left Intake
A=(0.0254-.16)+1.65
A=1.5154
So, do I go with 1.50?

Right intake
A=(.0762-.16)+1.75
A= 1.666
and this one would be 1.675? or 1.65?

Available shims: 1.200mm – 3.000mm in .025mm intervals

 

[Rich Rohrich]

PK, those intake valves are done. Forget the math and pull the head.

 

[Papakeith]

Damn, I was afraid someone was going to say that. :(

But, is my math right? ;)

 

[Rich Rohrich]

I stopped reading after I scanned down and saw the clearance. :)

Your stuff looks like the Honda formula which is obviously correct. If you are in between shims I always lean towards the loose side.

A couple of things to keep in mind:

- You ALWAYS have to measure the shim you are taking out to make sure it is the size you think it is. You'd be surprised how often they are mismarked.

- Even if you do the nice neat math the clearances don't always cooperate as expected. They usually do, but you ALWAYS have to verify the new clearance by turning the engine over by hand for a few cycles and then verifying the clearance again at TDC.

Just make sure you buy extra shims smaller and larger than you think you need, and don't be surprised if the dealer only stocks them in 005mm increments. ;)

My advice would be to buy a Hot Cams shim kit and save yourself a bunch of trips to the dealer. ;)

Investing in a good metric 0-25mm micrometer will save you a ton of grief , and the SK (Facom) 804.P Metric feeler gauge makes this a lot easier.
It has 19 blade sizes in 1/100mm (4-5-6-7-8-9-10-15-20-25-30-35-40-50-60-70-80-90-100) so you can measure the upper and lower limit of the clearance using a GO , NO-GO approach.

You can get the feeler gauge for $6.00 and it's worth 10 times that when you need it.

http://www.ultimategarage.com/shop/part.php?products_id=444&osCsid=13eda459d776c5c74effbee68fb91b59