Hi , i can take some photos of my wiring if that helps , ive just had to resolder some of mine aswell. My bike is an 04 rev3 250 that i got on gumtree as a basket case , im sure it never had the brown wire either , the red wire on mine goes to the coil aswell. I noticed you said you tried refitting the kill switch but did you try for a spark with it unplugged ? I actually found your thread via gumtree , its a nice bike with some nice upgrades , seems a shame to sell out of frustration. 

Having not had a usable trials bike all summer I got so p****d off I stuck it on Gumtree. I've calmed down a bit now I'm persevering. I've tried everything I can think of and for most of this time I had removed the Kill switch. Took it to a local Auto electric engineer yesterday. He couldn't see anything wrong with the set up but is going to check all the output values for me with the system on the bike.

No worries be interested to see the cause if you do find it I know too well how frustrating these things can be. Ive just put a techno gearbox in mine and had to shim the clutch to stop slipping but got it sorted and now have a mostly sound bike for just over £500 after doing the shock bearing etc. Keep us updated on how you get on and if needed i can do tests etc to compare.

Will do and thanks for the offer.

Finally the bike is running. To wrap this up for anyone else having similar problems: I had a local auto electrician look at it. At first he couldn't see anything wrong so decided to check out the stator output on his oscilloscope. He couldn't get a decent trace by just actuating the kick-start so tried driving the flywheel with a power drill. While doing this and monitoring the readout he noticed he was getting a spark. So it seems the reason the ignition would fire up on the Bradford Ignitions test rig but not on my bike was down to the speed of the rotor and the way I was checking for a spark. I had been holding the plug with one hand against the cylinder to earth and was cranking the kickstart with the other hand. I had no plug in the cylinder head so I wasn't working against compression. I've always checked for spark this way but is seems that on this bike this method doesn't generate enough speed or current to create a spark. Stick the plug back in the head, connect it up and give it a good hard kick and away it goes. Strange but true. Another lesson learned! 

Thanks to everyone who offered advice.

 Hate to ruin your thoughts, but I bet you still have a ground issue. You went forever with no spark, and now it runs. I have knowledge of a guy that has been chasing the same thing on my old `01 for about ten years. It started a few weeks ago and he was thrilled. Until it did not.

I agree as ive always checked for a spark the same way, dont get me wrong though my uncle has a gasgas txt which is pretty much the exact same. He replaced the kill switch then tested the spark but couldnt get any , put the old killswitch on still no spark. Put plug in kick the bike and it will fire first time.