XJ Valve Adjustment

Has anybody performed these valve adjustments by simply shimming the factory shims with shim-stock?

For example, if you measure .010 clearance & it should be between .004 & .006, you might cut a disc of .005 brass shim stock & place it under the factory shim.

This seems to be a reasonable fix.

Any experience or suggestions regarding this?

 

NO NO NO NO NO!!! The shimmed shim will spit out just about as soon as you start the motor and cause great destruction. FALSE ECONOMY don't destroy your motor to save $6!!!

 

Thank you for the reply. It's not that I don't believe you; I just don't understand why it would "spit out" of the depression in the bucket? Can you please elaborate on this.

And FYI the motivation is not to save $6, but to quickly be back on the road without having to wait for the shims to come in; I have tons of shim stock in my garage, but no spare shims.

Thanks.

 

have you checked the clearances yet? your valves are probably tight, not loose, so you would need not to add but to subtract from the existing shim.

definatly do not double stack shims, they will not stay. also, the shim stock you have is probably not dense enough and will squish causing the adjustment to be off after some run time.

why let the valve adjustment "down" the bike? ride it until the shims comes in, unless you have checked them and they are HORRIBLE....?

 

Hydraulic pressure will form between the Shim Stock and the under-side of the precision made Shim.
The hydraulic pressure will break the normal surface tension between the under-side of the Shim and the Valve Bucket Seat, and cause the Precision-made Shim to constantly "Float"

In that state, the inertia on the Precision Shim will be forcing the Precision Shim out of the Valve Bucket.
If the bottom of the Precision Shim escapes its Seat and you "Throw a Shim"... the Shim hangs-up on the lip of its Seat preventing the Cam Lobe from making its next full rotation.

The Camshaft stops or fractures.
A catastrophic engine failure ensues.
The resulting immediate loss of control places the rider and any passenger in great danger of bodily harm.

 

a big no no in other words

 

our man chacal is quick to ship and has every size shim you need in stock, you'll be on the hiway in no time at all

 

It's even simpler than breaking the surface tension, Rick. The lip on the top of the bucket is only so tall, tall enough to restrain A SHIM. NOT a "shim" made of layers. By putting shim stock under the shim itself, you would be reducing the amount of "lip" holding the actual shim in place, effectively raising it up toward clearing the "rim" of the bucket. This isn't a problem with thicker actual SHIMS, they are one piece and therefore always held by the entire width of the "lip." But if you put a .010 shim stock under a shim, it now has .010 LESS engagement with the lip that holds it in place, less and less the thicker the shim under the shim. A recipe for certain destruction.

 

Umm quick question.. When the valves and seat wear, the clearance usually closes instead of opens. If that is true then why are you .01 out of tolerance?? You might have other problems. Seems like you might have a burned valve or a stretched one.

I have never shimed a shim but I have surface ground a few thou out of them before. You need a surface grinder to do that job and always make sure that the ground surface is in the bucket, not on the cam side. Probably not something the home mechanic has unless he has access to a machine shop.

Sean