Riva 7 ports cylinder Superjet

[Big Kahuna]

Ok. Maybe a better way (layman’s) to say what I think the data suggest is.

For a given displacement (cc) (class rules) a square bore produces best results. The point would end when piston speeds get to high for the length of stroke for a large displacement. The port windows can flow more volume with a square bore for a given volume than a large bore smaller stroke. Does that help?

You do realize some are thinking you are talking about square pistons.

 

[Quinc]

You do realize some are thinking you are talking about square pistons.

shhhh you are giving away the next leap in Jetski tech.

 

[Storbeck]

Little bit of trivia the last of the motocross 250's were actually undersquare, they had longer stroke than bore diameter. This is still true for current model Yamaha and KTM 250's.

 

[kevbo]

Ive noticed whenever there is a displacement limit and when a tuned pipe is used they like the strokes at or longer than the bore size. I have also noticed much shorter strokes being selected whenever a pipe is impractical, and when the main priority is low weight. You will never see a long stroke chainsaw or outboard marine engine.

 

[waxhead]

Little bit of trivia the last of the motocross 250's were actually undersquare, they had longer stroke than bore diameter. This is still true for current model Yamaha and KTM 250's.

They did this to get the torque. It limited the top end hp but it gave more torque

 

[rob-noten]

Hey,

Did you bought that Riva Cylinder in France ?