thanks to every for the help, i've move on a bit now........
i traced one problem back to the starter, as the quad had been stood for a few months the previous owner had tried to start it not knowing the run switch had broken, so he had melted the bushess open, ive ordered a new one, but i fixed the old one by un-jaming the bushes any way but i dont think it will last long, so now its trying but not firing. i had to remove starter to fix it so i span the engine over by hand just to check it was not seized and its not, but now im wondering if the position of the fly wheel coraspons to the spark at plug ?, any ideas graitfuly recieved, dont serpose any one has or knows were i can get bushes and cercular plastic holder as this was the only thing wrong with other starter

 

I've never seen internal parts for the starter available. But starters are so cheap that replacing the starter seems the way to go.

If you look at the outside edge of the flywheel you will see a raised bump that passes in close proximity under the pickup coil (which is also mounted outside the flywheel). The spark occurs near the trailing edge of the raised bump. The bump produces a small signal in the pickup coil which fires the CDI which drives the ignition coil.

But the raised bump must be going by the pickup coil at speed - you can't turn the engine by hand and expect to trigger the CDI.