Thanks guys for the replys,
But i still cant get my head around this..... the bike came out the factory according to the original paperwork with an a10 casing (from new ) and a frame prefixed with a7 ( from new), also registered ( from new) as an a7 (500cc)engine ! i could kind of understand all this if the bike had had a new crankcase fitted due to an accident or the like but its the same number on it from its birth !!
The only other explanation is someone has removed the internals and swapped the head ect. if so, why ?
I also thought that it seems that this might be a late a7 and the factory "cobbled" it together with any bits lying around !
Again, many thanks for your imput, the bike has been stood around for over 20 years prior to me buying it, after cleaning the slip ring on the mag, and de lousing the carb, she fired up third kick !!!
Signboy