Engine seize? Plus rocket to jog conversion!

today i got my moped out and went for a drive after fitting a 107mm torque and clucth conversion to my previous 105mm on my mbk rocket , i should also mention that i changed the clutch springs from my old 105mm clutch which had leo vince yellows in them and put them in the new 107mm clucth with great difficulty, the reason ichanged to a 107mm is because there are more parts for that siza clutch anyways,
first thing i noticed was bike didnt really engage properly or if at all. then i carried on driving and it eventually shot of so i turned round going down a long hill at full throttle and then suddenly BANG engine died and kickstart wont move,took it home and removed the crankcase, i tried turning the flywheel with my hands and sure enough the rings or something have gone,

What i want to know?

1.is if this could of been caused by me fitting to tight clutch springs as they were for a 105mm and were very hard to fit

2.plus i have a minarelli horizontal engine from a yamaha jog i was thinking of buying the mounting brackets and fitting it to my rocket but was wondering how difficult it is wire up the engine,i will be paying someone else but just wanted to know if i would come into any problems with ignition coil output or what cdi to use.

I know guys lots of info, but would much appreciate peoples thoughts