Ok here is my dilemma. I just bought a 1976 Yamaha 4 stroke. I was told it was a 450 however I find no reference to it on the Bike or the internet. How can I find out what I have here. Its a nice bike loads of power. Looks like a Stainless or chrome tank. When I look online I see 500 TTs that have this tank but different markings on the tank. Help?