I was on ebay today looking around and found a stroker crank? Item # 1871434161
i was wondering just what it is. They way the man talks about it sounds like it should give your atv a big burst of power

Is it factory?
Is it aftermarket?

 

Stroker means the travel of the piston has been lenghtened to get a bigger displacement. Displacement is calculated using the bore size and piston stroke in mm.

One way to increase displacement is to bore out the cylinder

the other way is to stroke the crank, in the one picture on that auction you can see the crank pin was welded into the crank, this pin is aftermarket, the portion that the rod rides on is off center. This pin being off center moves the rod out further on the axis, thus the piston would travel further up and down the bore, increasing the displacement.