What would cause this?

So I started my aerox this morning left it to idle and warm up (cold weather) noticed the bike shaking backwards and forwards and all of sudden the bike shot forward and cut out and fell over (was a violent jolt) . started it up and the bike just juddered forward and cut out...feels like the crank etc. Any help much appreciated.

 

Sounds like rollers stuck out, check the vario

 

Would rollers cause that jolting and cutting out?. The bike rides fine when riding but it happens on stand still idling ?

 

check the clutch springs could have snapped one and a shoe is sticking
also as stevep mentions check rollers have not flat sided are are not returning back into the roller well fully.

 

Yes they would. Rollers get thrown out and engage the clutch which grips the wheel and makes it turn

 

Thanks mate!! I'll let u know how i get on with it