Something else the Japanese didn't invent

[Earl Svorks]

It may well be that the Genesis 5 valve engine came from Yamaha as a first.
I know of no other engine of this configuration. Any one who has had to adjust the valve clearances on one of these knows how big a pain, how expensive a pain,( if you're the owner) it can be.Yamaha made shims in increments of .01 mm, used in the factory where the engine was built. It seems the
dealer only had access to shims in increments of .05 mm. A non dealer service shop had little chance of getting the clearances exactly right. I have seen many a 5 valver that wouldn't even run
any more as the adjustment was put off too long, no clearance , leaking valves.
  My solution to this problem can be seen in the photos that follow. This was my own idea, design
and execution. This tool can be used to measure a shim. Simply put the shim on the mike stem, adjust the thimble 'till the shim is flush with the face and read the mike. it will show the size in metric
readings. Here's the cool part. As most of the time the shim you need is thinner than the one you have, just dial the mike up to the thickness desired, what part of the shim cap protrudes above the plate can be removed on the lapping plate or with a fine file as the mike can be held in the vice, no problem. The plate is big enough to be sure you can get a flat surface on the shim.
I have used this machine many times with unqualified success, every time.

[simi_ed]

So what I'm reading here is you're grinding the shim to fit the required gap.  As I remember, all shims are surface hardened.  Now, you're grinding off the hardened portion of the shim?  This seems like a bad idea 

[ribbert]

So what I'm reading here is you're grinding the shim to fit the required gap.  As I remember, all shims are surface hardened.  Now, you're grinding off the hardened portion of the shim?  This seems like a bad idea 

I'm reassembling my bike as I speak after having ground down 13 of the 16 she was silent now will sit point I wanted a milk makes it.

OK, so the voice to text has a few bugs in it.

I have just ground down 13 of my shims and they are now all within 0.01 of max clearance.

Noel

[simi_ed]

"Smart people learn from their mistakes. But the real sharp ones learn from the mistakes of others."   
― Brandon Mull, Fablehaven

Thanks for the heads up!

Ed

[Earl Svorks]

So what I'm reading here is you're grinding the shim to fit the required gap.  As I remember, all shims are surface hardened.  Now, you're grinding off the hardened portion of the shim?  This seems like a bad idea 

Hey Ed, yours is a valid point,and one that has already been considered. Because these are under bucket shims, there is no movement or rubbing action working against the top of of the shim. For this reason, they need not be ,and indeed are not very hard. If
how easily material can be removed with a mill bastard file is any indicator of the Rockwell index, which it surely is,,, well, I think it speaks for itself. When this style of shim, and I think the proper name for it is the "Winkler cap" is used the way Ford or Ducati have done, where the rocker arm
bears  directly upon same ,as it sits on the end of the valve, they are hardened just like any over bucket type shim. Hard as glass, and a file won't touch 'em.  Ask Noel,, he just filed a bunch of his down.

[Pat Conlon]

Interesting tool, thanks Earl!

So not only is the Genesis engine 5 valve (x4 = 20 valves) but it is shim under bucket?
The cams gotta come out to get to the shims?

Ouch!

[ribbert]

....... they are hardened just like any over bucket type shim. Hard as glass, and a file won't touch 'em.  Ask Noel,, he just filed a bunch of his down.

I should add, when you know what you can get away with sometimes you do just that, but crude grinding the shims in the garage was not a consideration. I did them on a milling machine, reducing the thickness by between 0.02 - 0.07mm.
I have no issue skimming them but they need to be perfectly uniform and smooth, mine are are as smooth on the milled side as they are on the original side and have only been reduced by about 0.5% of their total thickness.
When working at these tolerances you need very precise equipment. A gouge or scratch could well herald a fracture point. Having said that, I have pulled shims from motors that have clearly been ground with some sort of power tool at some point much earlier in their life, seemingly without issue. I guess the oil between the shim and the bucket will take up some discrepancies. Unlike the cam side, the load on the shim is distributed over it's entire surface area on the bucket.

I fired it up about an hour ago and one thing I hadn't even considered was the noticeably smoother idle, and I haven't even synced the carbs yet.

Noel

[JCainFJ]

I've never had a problem finding shims for any of my 4 Yamahas that use the 7.48mm O.D. shims. Cynthia's TDM has 48k and has never needed any shims and my dealer has either traded me for the ones I've needed for my FZR1000 , YZF600 and YZF1000 or been able to get them quickly. The shims I've had to buy were only about $9.00. The good thing about these bikes is that the valves use very light pressure springs, so the clearances almost never change. My YZF600 has over 50k miles and only 1 exhaust valve has gone out of spec.
The FJ's use 25mm O.D. shims and there are lots of "half step" (2.72 - 2.75 - 2.78) Honda shims out there. My air cooled FJ's have needed more valve clearance adjustments then my other liquid cooled bikes.

[fj johnnie]

 The Yamaha five valve engines have a 40,000 kilometer valve adjustment interval. So once the initial break in check is done it takes a while before it is needed. However many five valve motors are not checked at 5,000k due to the cost. That is a problem that has caused a lot of premature failures.

[Fj.itis]

I just tip the top of the valves ever so gently, it requires a bit of mucking round to get them perfect clearance but it works if you got the time. Thats how the head recon guys showed me how to do it, he hardly buys new shims unless they need bigger ones. I got all my clearances spot on within the range specified.

[Earl Svorks]

I just tip the top of the valves ever so gently, it requires a bit of mucking round to get them perfect clearance but it works if you got the time. Thats how the head recon guys showed me how to do it, he hardly buys new shims unless they need bigger ones. I got all my clearances spot on within the range specified.  When the head is off and the valves/seats are being attended to,the machinist can and should adjust the assembled height of each valve assembly for correct spring preload and valve clearance. I've been tempted but have never attempted to take material off the end of the valve with the head on the motor, as your post suggests, maybe I made the wrong inference ?

[Fj.itis]

Sorry i made the mistake thinking that you had the head off. I definitely don't do this with the head on sorry for the confusion.