Question for the Gurus

[Terry Jackson]

Anyone ever play with rod length on a 2 stroke?
On 4 strokes longer is generally better, but is seems on 2 strokes, shorter might be better. A short rod makes the piston hang around the bottom,increasing port timing without changing port heights. Since the piston moves down faster, the crankcase pressure would build quicker, had have more time to pump into the combustion chamber. I would liken a shorter rod to tightening up the lobe centers on a 4 stroke, rougher idle, faster drop beyond peak HP, but more torque & HP in the usable range.
Do you race guys play with this?
Is this getting in the areas where no one lets out info that may help their competition?

[T-REX]

I know of sum ov da boyz dat been playing wit pin locations in the pistons, and stroked cranks...but all the rods are the same lenght...the results have very mixed results...REX:cool:

[Raceman]

Yamaha came with long rod kits for their YZ's several years back and they followed into production several years later.


Short rods in themselves can carry a load of heavy baggage. There's increased side loading in the cyl walls and the increase in piston speed you mentioned is almost always a bad thing.