Bore And Stroke

vmaxdad8657

vmaxdad8657

New member
Joined
Dec 29, 2004
Messages
76
Age
66
Location
Upstate New York
When I was a kid growing up ( early 70's / SS-338, SS-396 ),
I learned that the 396 cylinders would fit on the 338
the stroke was the same, just a bigger bore.
Then if you bored the 396 .120 over, it was 433 cc
A year later with the SS-433

I learned from coming to this site. that you could take a 643 piston, and bore your 292 out to a 322 and use the 643 pistons, Stroke was the same?

What about the GP 246 and GP 292
I dont think that you can put a 292 piston in the 246.
Isn't the 246 a shorter stroke?

Can you use any of the old air cooled 250 MX pistons, cylinders, heads,
from the 70's on the GP 246?
Were the GP246 snowmobiles the same bore and stroke as their 250 cc dirt bikes and early motorcross bikes?

Just trying to figure what could be done to a GP 246,
shy of putting a GP 292, SS 292 or SR 292 motor into it.
 

SS 292? Sorry, I can't answer any of your questions, my time was spent with the twins you mentioned and not the singles. But I couldn't help notice 'SS 292', I've never heard of such an animal, can you enlighten me? G.
 
vmaxdad8657 said:
When I was a kid growing up ( early 70's / SS-338, SS-396 ),
I learned that the 396 cylinders would fit on the 338
the stroke was the same, just a bigger bore.
Then if you bored the 396 .120 over, it was 433 cc
A year later with the SS-433

I learned from coming to this site. that you could take a 643 piston, and bore your 292 out to a 322 and use the 643 pistons, Stroke was the same?

What about the GP 246 and GP 292
I dont think that you can put a 292 piston in the 246.
Isn't the 246 a shorter stroke?

Can you use any of the old air cooled 250 MX pistons, cylinders, heads,
from the 70's on the GP 246?
Were the GP246 snowmobiles the same bore and stroke as their 250 cc dirt bikes and early motorcross bikes?

Just trying to figure what could be done to a GP 246,
shy of putting a GP 292, SS 292 or SR 292 motor into it.
Click to expand...


GP246 and GP, SL, SM, GS, and SR 292 have the same bore. 73mm. The gp246 has a shorter stroke. You can use 292 pistons in 246 motors, all you have to do is cut the piston down. Same goes for the enticer 250.
 
Gorkon said:
SS 292? Sorry, I can't answer any of your questions, my time was spent with the twins you mentioned and not the singles. But I couldn't help notice 'SS 292', I've never heard of such an animal, can you enlighten me? G.
Click to expand...


Yamaha made SL, GP, SS, SR...etc......

I knew they made GYT kits to convert them to
"SS" "SR" specs.....

I agree with you about the SS-292...( never made one )
We had SL-292's and GP-292's
 
vmaxdad8657 said:
Yamaha made SL, GP, SS, SR...etc......

I knew they made GYT kits to convert them to
"SS" "SR" specs.....

I agree with you about the SS-292...( never made one )
We had SL-292's and GP-292's
Click to expand...


No ss, they made a gyt cylinder in 71, the cylinder on the side says "292 cc S" That was to upgrade your 71 into a hd carb and GP292 porting specs. (which i have one for sale) They never made any cylinder that was the same specs to an sr that i know off. SR was reed ralve too.
 
Thank-you for that, I knew that I had never heard of an SS 292, but I'm being a little more cautious since finding my SS 338 which I never knew existed before either.

The SR 292 being reed valve is news to me as well! Cool. G.
 
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