i have just over hauled a dk which had the factory conversion fitted and still had 2 head gaskets , it ran fine but needed a good decoke , i fitted a flat top piston just to make it correct and it runs fine but it shakes , crank / flywheel run true , timing spot on it is a 2hp 1000 rpm engine with the smaller flywheel , its ok at 750/800 rpm so might just change the gov springs , has anyone got any ideas ? my other 2 ''d's '' run dead smooth but are both 1.5hp 750 rpm units