what do you think about this crazy idea

[chiz]

OK  I know valve shims are as hard as diamonds but was thinking if you needed a thinner one could you not not brush it down on a wet stone? Conversely if you need a thicker one could you not  add a circle of steel shimstock under the shim?
Lez

[red]

OK  I know valve shims are as hard as diamonds but was thinking if you needed a thinner one could you not not brush it down on a wet stone? Conversely if you need a thicker one could you not  add a circle of steel shimstock under the shim?
Lez

Lez,

You may be able to whetstone a thicker shim to a thinner spec, but if the reduced shim has numbers left on it, that wrong info may complicate any future shim adjustments.  Just a thought.  I would not want any substitutes for real shims in the valve train, because they may wear or fail in unexpected ways.  To me, the correct shims seem like a very minor expense, over the lifetime of an engine.  You may be able to "rent" a full shim kit through members here, paying only for the convenience and the shims that you need there, not the full price of the kit.

[MOTOMYSZOR]

reducing shims thickness is quite easy if You have special magnetic grinder.
adding thickness by putting something under ....  


I think that any "savings" on shims are.... let say senseless

[Pat Conlon]

Didn't I read somewhere that the shims were surface hardened?

If so, that would mean grinding down the cam side would be a no-no, the bucket side not an issue.

Sounds like a lot of work when shims are only $8.00 each and readily available.

[Tuned forks]

i agree with Pat.  I would be surprised if the shims were not hardened steel and that hardness is measured in thousands of an inch.  Yeah Lez, the shims are kinda pricey when you have to replace eight of them or so.  Talk to Randy or Robert.

Joe

[T Legg]

  I prefer to use regular shims but it is hard to get half sizes. I grind mine if i cant find what i need .i always grind the numbers off and use the unground side for the cam lobe. i grind them by hand by putting a peice of plumbers sandcloth on top of a large metal file(to hold the sand cloth from slipping)and then sliding it back and forth across the sandcloth.the shims dont get very hot much cooler than a running engine so it wont ruin the temper of the steel and it has a mirror finish when its done.since valves get tighter over time you can keep grinding the shims.it isnt very fast so you arent saving money if you value your time but you can finish the job without ordering parts. 

[racerrad8]

  I prefer to use regular shims but it is hard to get half sizes. I grind mine if i cant find what i need.

FYI, I have every size Yamaha shim from 200-320 including the "2" & "8" sizes not available at your local Yamaha dealer.

Genuine Yamaha Valve Shim

I do not recommend grinding, sanding or honing them unless you have the appropriate holding fixture to keep them flat. We have hundreds of "modified" shims over the years and most of them do not have a parallel surface. One side is usually thicker than the other.

An old machine shop in town used to have one when I was just getting started with the FJ 24+ years ago. We could use the holding fixture and grind them with the valve grinding machine. They went out of business and I did not get a chance to buy that tool. But now that I have every size in stock, there is no reason to grind shim.



Randy - RPM

[PaulG]

Sounds like a lot of work when shims are only $8.00 each and readily available.

With my last valve adjustment I only needed one shim.  My local Yamaha dealer tossed me one for free.  Miracles happen.

[giantkiller]

Yah my local dealer actually exchanges them for free.

[ribbert]

I know every tip, trick and method of grinding shims and I know exactly what can be gotten away with and what can't but I don't recommend any of them unless you are in a bind. If you have access to replacement shims, that is your best option.

My advice, "Don't try this at Home" The fact that you may have gotten away with it previously does not by default make it a good idea.

Just to get in first in case someone calls me out, I grind my shims but that's a bit different. I measure them, pull the camshafts and take them to a vintage automotive machine shop I use. They have a machine literally made for this purpose that guarantees micron perfect uniformity.
The advantage for me is that it's faster and easier than ordering shims (and they don't charge me because it's for my own bike) and all the valves are then set to exactly max clearance, not near to but spot on. I last did this 60k ago and they were still pretty good when last checked.

I have previously worked out that the reduction in thickness for a typical valve adjustment is no more than a few percent of the total shim thickness, not enough to be concerned about compromising the strength of the shim.

At 250,000km and going strong, I must have got an engine from a good batch of Jap steel!

Noel

[Paul.1478]

  I prefer to use regular shims but it is hard to get half sizes. I grind mine if i cant find what i need.

FYI, I have every size Yamaha shim from 200-320 including the "2" & "8" sizes not available at your local Yamaha dealer.

Genuine Yamaha Valve Shim

I do not recommend grinding, sanding or honing them unless you have the appropriate holding fixture to keep them flat. We have hundreds of "modified" shims over the years and most of them do not have a parallel surface. One side is usually thicker than the other.

An old machine shop in town used to have one when I was just getting started with the FJ 24+ years ago. We could use the holding fixture and grind them with the valve grinding machine. They went out of business and I did not get a chance to buy that tool. But now that I have every size in stock, there is no reason to grind shim.



Randy - RPM

I know I am new to this form and bike but do you guys know how lucky you are to have RPM? these guys have everything and are all over the form and willing to help anyone who asks. I know were I will be getting my shims from (and the valve cover gasket). I am positive they will do a great job on by carbs and forks.

[Tuned forks]

Paul, I'm sitting in RPM's shop right now. First time meeting Randy and Robert face to face. I can testify they are the real deal, as nice in person as when doing business. You are so correct about how fortunate FJ Owners are to have patrons like this forum, RPM and the Raduechels.  My FZR 1000 is same year & manufacturer as the FJ but it doesnt have nearly the same support.  We are fortunate.

Joe