433 motor question!!! Identification Help!!

[snowpromod]

Hi, I have these two Yamaha motors listed below, does the R on the cylinder mean anything different than the SF?? Any help on the application of these two would be greatly appreciated!

1. Yamaha Snowmobile Motor
• Year unknown
• Crank #S433-017309
• Head and Cylinder #433CC SF


2. Yamaha Snowmobile Motor
• Year unknown
• Crank #S433-015936
• Head and Cylinder #433CC R
• Keihin twin carbs #844EI

 

[montynormand]

sounds to me like a '74 GP433 motor (f)
and also the '71 SR433 (r) motor.
I have the cylinders for a '71 sr, but am looing for the heads. I am picking away at building a '71 SR replica racer, so if you ever decide to part with the head or cylinder please give me a chance to purchase
thanks

 

[Snojet Steve]

#1... 433cc SF is 1978 Exciter 433. 1974 Yamaha 433 R/V engines use "SB 433" in their designation, SC is 75', SD is 76'.... and so on.

#2... no clue.

 

[montynormand]

sorry if I lead you a-stray. I know my 70-73 stuff pretty well, but the knowledge drops sharply after that. LOL
I based my '74 GP433 callout as that was the gp433(f) modles
I am correct regarding the 433cc R cylinders thought

Monty

 

[YAMAHABUNCH]

Engine #1 Is A 78 Exciter 440 And Engine #2 Is A 73 Gp 433b
For Sure !