It does sound like a starter clutch problem,in the drive train, between the starter motor and the engine is a "sprag clutch" or if you like a device which permits rotation of the engine by the starter but not rotation of the starter by the engine, a sort of "one way" device.They can be fixed quite often, but not always.It is easy to buy replacement springs and rollers, and also (but not so easy) the plungers.There are six of these little blighters, with each spring about the size of a biro type.If all the plungers are "free" then you are laughing, and its not too hard to do, but if they have seized in their bores (likely) then they can be quite a bitch to get out.In the end though if extraction by fair means or foul of these little plungers fails,(I usually tack a weld rod to them and then twist and lever out) the unit can be seperated, by grinding off the rivet heads which hold the component parts of the cklutch togethere, and then with the application of lots (and I do mean lots) of heat, the whole caboodle can be got apart.Much simpler would be to source a used item, shouldnt prove too hard to get, but in order to do this repair you will be removeing the genarator cover, and then the inner caseing, together with the generator stator, not hard to do, with the exception of the corect bolt to remove the generator (the front wheel spindle can be used).It wont affect the ignition, as on series 11's this is on the front of the primary cover.
If the bike is a good one, I would not be put off by this, but as every seller would say, "its easy to fix" not actually every time, no its not.
CLEM
