I recenctly bought a 1973 gp433b with a stuck motor . I am in the process of rebuilding the motor when i noticed 2 different style jugs on it . The motor # is s433-012403. The mag side jug has smaller intake and exhaust ports with a w stamped on it by the intake,it had an oem piston with 2 rings.The pto side jug had larger intake and exhaust ports with a r stamped on it by the base,the piston was an aftermarket one with only one ring. Which cylinder and piston is correct for this motor.Motor also had dual carbs. Thanks for any info.
Yamaha Nutz
New member
the single ring "R" cylinder is the right one .......w motor from sl sw sleds sled should have twin carbs too