What is the difference between the it 490 engine and yz?

Answer 1

1. it490- 5 speed....yz490 4 speed. 2. yz490 has lighter, balanced crankshaft. this motor spins easier and higher, however, this is what causes the vibration as a yz/it piston is a heavy thing. 3. Same cases. 4. yz piston has slightly higher dome (more compression) 5. yz barrell has bigger exhaust port, however barrels are interchangeable. 6. 40 mill carby for yz- it has 38 mill. these are interchangeable. there may be more differences, i havent really checked properly, however there is interchangeability as mentioned.