Valve clearances

I do find it disturbing after all these years that errors are repeated time and again.
How many have stripped threads or will strip them in the future because they have been mislead?

I think Grants idea is a good one.
 
At the risk of asking yet another stupid question...at the beginning of this thread the valve clearance values for F1 cams were stated as 0.2 inlet, 0.25 exhaust.  I went to the Laverdamania site and for A11 cams they list values of 0.25mm inlet, 0.30mm exhaust.  I have 4C cams so...I checked the archives and didn't find anything there.  Does anyone know the values for my 4C cams?
 
Think 0.2 in and 0.25 exhaust are considered as safe minimum clearance for all triples/cam profiles and one shouldn't go below those figures. My old 3C manual says 0.25 to 0.35 on all valves. It's said that going too far to the upper limit might affect clean idling. Better than burnt valves, at least. :D
 
According to my archives (don't remember where I sourced the info) minimum clearances for inlet and exhaust respectively should be
A11 - 0.25, 0.30
A12 - 0.10, 0.10 (seems a bit tight)
4C - 0.20, 0.25
F1 - 0.20, 0.25

Maximum clearances are 0.05mm greater than minimum, except for A12 where the max is 0.20 for both inlet and exhaust.

I made up a little Excel spread sheet for doing valve clearances. Put in your cam type, existing clearances, shim sizes, and it'll tell you what shims you need. I know, it isn't rocket science, but it saves me making dumb arithmetic mistakes. I save the file with a new date and mileage each time so it keeps a record.


PS: Happy to share the Excel file. I've added it as an attachment.
 

Attachments

I was quoted $9.00 each Australian (plus GST/tax if applicable, plus post) by Precision Shims - theirs are hardened to a depth of 0.3mm. 
Went with Wolfgang who is cheaper @ $7 CAN plus post
 
SimonR501 said:
I would guess that if the material is too soft then the constant pounding of the valve would flog out the shims.
Click to expand...


I can see where you're coming from: doubtful though. I expect shims are turned to size from a bar of hardened steel and that's it. Whether you buy or lap one to size is probably the same difference..
 
AndyW said:
I can see where you're coming from: doubtful though. I expect shims are turned to size from a bar of hardened steel and that's it. Whether you buy or lap one to size is probably the same difference..
Click to expand...

Rather than have me blather on, it might be better to read this:
http://www.practicalmachinist.com/vb/general/making-valve-shims-motorcycle-have-questions-178704/
 
blab said:
I'ts a fairly new motor.
Once I get the clearances right it will be ready to roll.
I guess more clearance is preferable to less, which is what I have now.
Click to expand...
1.6 for inlets and  2.0 to 2.2 is fine with modern valves..as are in your engine... ...run the Cico at 6 and 8 thou.

They dont grow anywhere near as much as the original valves do when hot..

If too  loose as can cause other issues such as damage to the buckets or the shim popping off and jamming...
( But what would I know as only been adjusting valve clearances for a mere 40 plus years )
 
You must log in or register to reply here.
Back
Top