the bike should be yamaha RD200 DX according to specs you mentioned. can you confirm if it has a single carb or twin carburetor. performance of the two was quite different as twin carb model has reed valves and single carb model intake was controlled by the ports and skirts of the piston which was not a very effective method. pls post some pics Adil, i might be interested in getting my 3rd RD, as it may serve as a donor for the other one.
regards