While my clutch is better since changing the oil to 10w/30 Lucas, I decided to take it apart and buff the steels, which I didn't do when I put the new friction plates in, and check measurements again. The springs are still just under 31.5mm (good) and the friction plates are all just under 4mm (most around 3.85 to 3.96). I buffed the steels with 400 grit wet/dry and cleaned them, and cleaned/dried the friction plates and gave them a gentle circular sand on a sheet of 400 grit taped to a flat surface. I have them soaking in oil now, before installing.

My question: I've read of folks using washers under the head of the clutch bolt to preload the springs a bit more. I happen to have some split lock washers (2.3mm thick) that fit the bolts perfectly, and I flattened them. Thumbs up, or down on using these? I know Barnett makes heavy duty springs, but I've read they may be too stiff.

What model bike is it?  I've personally tried that on a rt3 motor, and I wasn't a fan of it.  The springs felt like they were starting to coil bind when the clutch was fully disengaged.  I know it's different for other models, but 360 clutch has 1 thicker steel plate, and that did bite me one time.  Also I've had bad luck with aftermarket steel plates.  I just reuse factory steel but clean them as necessary.  I upgraded to mx360/sc500 springs to keep it a little stiffer.

It's a CT-1, with the original steels and aftermarket friction plates, and the springs were new a year or so ago. The steels look much better now, and it may be okay without the washers. However, I might install them and see how the clutch lever feels, before putting the side cover back on and filling it.

No harm in trying.  At full disengage, it felt goofy to me.  Unsure how the helix is designed on the ct's, but I know for sure they are weak on the dt/rt motors.  That extra stress can break them that much easier.  Mine broke long ago, and I replaced it with a brass one.  Seems like a much better deal.

Turns out the washers are slightly larger than the bolt heads, so do not fit in the recesses. Oh well. Putting it back together without them, and will see if scuffing the steels helped.

I'm not following entirely, was the clutch slipping?

Shimming clutch springs was common on YZ's  put the shim in the bottom, check for coil binding with the cover off, I know you already are.going back together shimless, just sharing what I've seen and done myself

Yes, it was slipping, especially when I was using 20w/40 Yamalube, and moreso when cold. I recently put in 10w/30 Lucas for wet clutches, and that improved it, but it was still slipping a bit , even when it was warm. I just  put it together and went for a ride, and it is much better after scuffing up the steels. I think I'll call this good for now.

Hey Tom. I am looking at doing the springs and friction plates on my CT1B this weekend and will be sure to scuff up the steels like you just described. I ordered the same plates and springs as you did. I also have to try and break free the little hex nut on the clutch adjustment screw. Someone before me had buggered it up pretty bad and I wasn’t able to break it loose when I tried to make an adjustment a few years ago. No sense in doing new plates if I can’t adjust them properly……

Schu, I didn't post a before pic of the steels, but the scuffing really did improve the look. I think some old original friction plate material was embedded in parts of them, but there was no evidence of burning, and no warpage at all. I used one of those hard rubber 3M sanding blocks with 400 wet/dry and a flat surface.

A reminder... Make sure you don't lose the steel washer that goes on the nylon gear at the front. It always falls off when you remove the side case, and mine ended up on top of the skid plate. Took a while to find it, but I heard something fall when pulling the case off.