Parts may have been change over the years, here are the basic visual differences between the two.
Mk 1- Silver barrells, RH4 head, straight chain guard without the black kicker, perforated seat.
Mk 2- Black barrells, RH10 head, chain guard has Black kicker, Square pattern seat.
A few others, Mk 1 intake manifolds are 32 x 32 to match up to RH4 head.
Mk 2 intake manifolds are 32 x 30 to match up to RH10 head.
Somewhere along the line, second gear ratio was chnaged.
The head markings are above the right exhaust and can usually be seen when tank is removed.
Welcome aboard....
