I was able to get the bike out and ride up/down the driveway to test the clutch.  (A longer ride is not possible as the roads are covered in salt).

It works fine - it really doesn't feel any different.  There are 2 new plates that likely need a bit of wearing in - but it engages and releases just fine.

The hub boss is 1.730”.  You want clearance similar to the stock setup.  The stock hub boss is 1.335” and the stock pressure disc is 1.340”, so stock clearance is .005”.  I suggest you bore your pressure disc to 1.735” -1.740”.

Heads up on this clutch mod, mine started to slip after I threw on a new high flow muffler.  The new muffler flows very close to your black Mac muffler.  So, again I have found the clutch to be a weak link.

All clutch components look fine.  All seven fiber plates are .115”.  All six steels are .062”.  The springs all have the same force at installed height as they had when new.  It just can’t handle the power.  Only remaining option is stiffer springs.  I’m gonna go with the early DR650 springs.  I,ve triple checked and they don’t coil bind so that shouldn’t be a problem unless I get stupid and adjust the cable way too tight.

It will be a while before I can test it.

The sintered throw out is The weak link. If you are going to increase the spring pressure I would suggest keeping a spare throwout around. Getting a hunk of material and making one is the best answer I can come up with.
I put a washer under the springs and mine broke.

I am already into to the engine mods, so no turning back.  At this point, the 13 plate clutch is better than the stock with these engine mods.  In my mind it would slip less than an 11 plate set up - as DBM said, more surface area.  I will put some thought into the actuation geometry and parts design to see if I can help come up with another solution to the slip issue.  I also have some mechanical engineer friends from my career days, maybe replacing some parts made with stronger materials/design could ease the failure mode of the weak link...

Mike:

I wonder if the broken clutch release pawl is caused by the loose fit on the shaft....as much as using washers to increase preload or using stiffer springs?

When I had my Cafe' bike apart I took the shaft apart and I saw the same wear pattern as you had....my bike has 15,000 miles on it.  I put in the little metal shim that you invented to tighten things up.

The wear marks in the pictures posted would indicate more force being applied outward instead of only on the flat turning the shaft.  Slop could be a contributing factor in the pawl failure.  Welding or soldering the pawl to the shaft would be a good experiment to see if the pawl would still fail under stiffer springs.  Any more pictures of failed pawls?

I have wondered if welding/brazing/soldering steel reinforcement plates on the side of the cam would help to strengthen it.  I don't know how heat would affect the strength of the metal it is made from....soldering would impose the least amount of heat.

Here is a thread with photos of a broken cam.

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1533781090

It appears the break happens at the "thinnest" portion of the part that is opposing the load.

I looked on YouTube to see if/how welding can be done on a sintered part - I didn't see anything.

Here is how sintered parts are made:

https://www.youtube.com/watch?v=z5327SSM6G0