My secondary pulley spring (the big one) still vibrates against the hub/centre boss, I have turned the spring end for end and it's still vibrating.
This time I gave the spring a good look over and the only thing I can see is one end is not flat or at right angles to the side's causing the spring (when fitted) to bow in on one side and out on the other, I think this is what is causing the vibration.
I have  a new spring on order but I'm tempted to try and heat the spring so I can level the last coil, with the hope that it sit's nicely 

[2015 Z Force 800 53/Trail EPS]

Well..if you heat the spring and not re-temper it the same as the factory, it will either break, stretch or do something other then it was supposed to do. Mine isn't flat on one end either..but it is pretty flat on the other...and that's the end I point down.

At the moment I'm more worried about it breaking due to the vibration

[2015 Z Force 800 53/Trail EPS]

At the moment I'm more worried about it breaking due to the vibration

I'm not sure how it can vibrate with the preload on it. I know one way mine rubs the boss and the other way it doesn't. Are you sure your exhaust springs are rubbing that "U" shield on one end? Mine were and made a hell of a racket..thought it was clutch-related.

I've replaced the exhaust springs for better one's and fitted silicone tube to the springs in an attempt to find the source of the buzzing/vibrating, they don't touch the heat shield so I'm confident it's not them making the noise.
My hub or boss had rub marks on one side and after flipping the spring it now has rub marks on the other side

I'm fairly sure the spring end that is not flat or square to the side's of the spring are causing it to bow out on one side and with the centrifugal force pulling that bow side out further the other side of the spring come's into contact with the hub causing the chatter/vibration

I have replaced the wet clutch as this was thought to be at fault but the noise continues

Back to heating spring steel or any heat treated steel for that matter.  If you heat it up and then let it cool slow you will soften it. No more springyness. If you cool it fast than it will be harder than before and brittle and break. Should you be determined to do it, heat it up and get it the shape you want. Quench it in oil let cool to room temp. After that temper at 475 for 2 hours twice letting it cool to room temp between.

I wouldn't heat a spring. They are pretty inexpensive aren't they? I would just get the new on in there.

Back to heating spring steel or any heat treated steel for that matter.  If you heat it up and then let it cool slow you will soften it. No more springyness. If you cool it fast than it will be harder than before and brittle and break. Should you be determined to do it, heat it up and get it the shape you want. Quench it in oil let cool to room temp. After that temper at 475 for 2 hours twice letting it cool to room temp between.

Im not saying you are wrong in ANY of your above statement...But Im sure you realize the amount of work you are talking about when you can replace the spring for $30 LOL

[2015 Z Force 800 53/Trail EPS]

I wouldn't heat a spring. They are pretty inexpensive aren't they? I would just get the new on in there.

Naa...30-something bucks. Looks like there are some bad springs out there so I hope the new one fixes davidpaul's.

I think I had underestimated the work involved in heating and bending a spring, last night I watched a vid on YouTube of a guy practising the process which showed some interesting results, the only difference being that I didn't intend heating the hole spring as he did in his tests.
When he heated the whole spring to red hot and allowed to cool slowly the spring lost most of its memory, so when stretched a fair amount it stayed in that position but didn't break.
I only intended to heat a small area so I could rotate the last coil up to a flatter position, I'm not sure what difference it will make to the spring if it looses some of it's spring memory over say 1" of the springs total length.

I have a new spring on order, I'm just thinking out loud as the saying goes

Just a thought. Do you have the old rear shocks? The ones with the helper springs?
Before the upgraded shocks my rear shock spring vibration rattled like hell against the shock. Sounded like the engine was knocking.

I wouldn't mess with it for $30.

Does anyone know the inner diameter of the big spring ?