Resolution on K&L Valve Shims

[MaxD]

I've had a different thread going asking about good sources for valve shims, given that Suzuki shims are running $16 each and have to be special ordered.  I've been getting great information from the forum members on valve adjustment and shims, along with the warning that K&L shims have a reputation for breaking and causing severe engine damage.  Not wanting to reward Suzuki for that extreme price mark-up, I have wanted to get to the bottom of this and find a better source of safe valve shims, preferably in kit form form for best convenience in keeping the exhaust clearance right at the high end of the spec range where the valve recession is minimized. 

I think this has come to a reliable resolution.  I talked to K&L tech support (408-727-6767 ext. 210, San Jose, CA) on this, and they seemed very honest about it.  Anthony there reports that they had never had a problem with their shims in any bike, and then in 2014 they had a sudden burst of 6 shim failures on GS500's, spread over the world.  They analyzed the problem and found that the subcontractor who made the shims had over-hardened them.  They paid for the damages, switched to a new sub-contractor, and have had no failures since then in GS500's or any other bike.

Based on that, I ordered one of their 13-7008 shim kits, $111 on Amazon (list price $165).  It has two each of 2.3, 2.4, 2.5, 2.55, 2.6, 2.7, 2.8, 2.85, 2.9, and 3.0mm.  I supplemented it with a bag of 5 of the 2.65mm for $31.  My understanding was they run about 2.7 out of the factory and tend to need thinner from there. 

There are a few Amazon offerings for $7.95 that say bag of five.  My guess on those is that they are mis-marked single shims, but if they really are bags of five they might be so cheap because they are OLD shims that have a possibility of being bad.  So, I'm staying away from those and from any K&L shims on E-Bay.  The E-Bay shims would be particularly dangerous, as there may be no way to tell when they were made. 

But, based on how honest they seem about the problem at K&L, I personally feel safe about brand new shims from K&L. 

I posted this under the previous thread also, but to make sure the word got out I thought it worthy of a stand-alone post as well. 

[crackin]

Why don't you just get the shims machined down a couple of thou at an engine reconditioning  shop, I do it all the time with no problem.
I ride my bike at speeds of up to 170kms hitting redline in every gear all the time and have never had any failures.

[MaxD]

Crackin, if that can be done without weakening the shim, it sounds like an excellent idea.  If it's cheap to thin down then it's saving money, and it also allows for getting steps in-between the minimum available 0.05mm in order to really keep that exhaust clearance fine trimmed as recommended by gsJack.  But, if the hardening they do is a function of shim thickness, then I would think they could only be safely thinned a little.  I tried to call Anthony back several times to ask, and did not catch him in his office.  I'll report what he says when I do catch him.   

Incidentally, I could not find any Moose or Hot Cams brand shims in 29.5mm outer diameter.  As far as I can tell, it's either K&L or pay twice the price for OEM.  Though there are no reported problems on OEM that I have heard about, my guess would be that Suzuki subcontracts their production rather than tying up capacity with that little bit of production.  I would not be surprised if they got them from the same source as K&L. 

[The Buddha]

I had thicker shims than 2.7 in mine. In fact my 48K miler seemed to get thicker even though one was @2.55, it still got thicker.
I also used to run the shims tighter end of the spec and ran the bike in commute conditions almost daily, short rides with super thick oil and rarely getting warm enough and staying warm. So 15 mile rides with 60wt Valvoline = shims getting thicker.
Cool.
Buddha.

[crackin]

One of my inlet valves is about 3 thou from being at Suzuki minimum spec, I have had it machined atleast four times. There is not a mark on it.

[MaxD]

Crackin, I don't know much about these mechanical issues except what I am told or read.  I note in "The Essential Guide to Motorcycle Maintenance" p. 25: "Normally when a valve seat needs renewing it is simply recut with a special tool."  If you are about to hit the minimum, maybe you can have that seat repaired.  I do see on-line some services fixing those valve seats, and claiming they are better than new with better heat conduction.  For example:

http://www.ridejbi.com/jbi-cylinder-head-valve-seat-replacement/

These guys are in Chandler, AZ, USA, and report they replace a valve seat for $60, and then only $40 for any additional seats in the same head.

[herennow]

A trick we used to do was to grind a small amount off the end of the valve to recover a bit of space. 

[The Buddha]

A trick we used to do was to grind a small amount off the end of the valve to recover a bit of space.

You cant do that on a GS without taking the motor apart. The valves are in a pretty deep hole. You could machine the bucket and hope you don't blow through it though, in fact much better than grinding the valve stem anyway, buckets are replaceable.
Cool.
Buddha.

[MaxD]

I checked with K&S on what they thought about thinning down the shims as Crackin suggested, and here is the e-mail reply:

"I am not sure if it would be ok to grind these down.  ( I don't know enough about these to answer the question properly)

I will try to email the vendor and see what they say but I would assume they would be against that?

Respectfully,

Anthony Morter
R&D and Tech support
K&L Supply Co., Inc.
2099 S. 10th St, Unit #80, San Jose, CA  95112
Tel: 408-727-6767 (ext. 210)
Fax: 408-727-4842
Online: www.klsupply.com"

I followed up by phone with Anthony, and he said he did just not know enough about the detailed metallurgy of the shim to be sure of:
1.  How much they can be thinned before possible hardening as a function of thickness becomes an issue, and
2.  If there was an issue of starting micro-cracks that could lead to shim breakage.

I mentioned that at least one of the users on GStwin made a common habit of machining the shims down thinner, and had not had any problem.  But, Anthony notes that one guy is not much of statistical trial.  Even back when they had their problem in 2014, that was only 4 to 6 shims that failed out of tens of thousands installed.  When the failure rate is that low, you cannot uncover it unless you are testing thousands of shims.  You might thin a thousand of them and have no problems at all, and then on 1001 it might break and ruin your engine. 

He's going to ask the manufacturer, and if they have any opinion he will get back with us. 

Personally, unless the manufacturer comes back with a strong NO, I think I am going to try thinning a few to have an option between the 0.05m steps.  That is only a few hundredths of a mm and should have no real hardening process difference.  I'll check them under a microscope I happen to have handy, and if they have no cracks from the machining process, I'll assume they are OK.