What fails first in a stroker motor? I was looking at the piston speeds of a stock crank at 10krpm vs a +6 mm stroker crank. Piston speeds at 10krpm on a stock stroke are already pretty darn high at 21 m/s (~4100 FPM). Speed at 10krpm for the 6 mm stroker is 23 m/s (~4500 FPM).
Those of you with big bore stroker engines, do you drop the redline or can a set of heavy duty rods (carrillos, goldens, etc) handle the speeds and G-forces seen at 10K? What about ring flutter and sealing issues at those speeds? Or is the valve train still the weakest point with respect to RPM?
The reason I am interested is because I was considering the benefits of destroking a crank to allow for higher rpm and less piston speed. But if the valve train is still the limiting factor, destroking wouldnt really be all too smart for reliable power development.
Many modern bikes employ an oversquare design with stroke ratios around 1.2 to 1.5 and up. They develop great power vs. size at high rpm. But aftermarket still provides stroker systems for these little zingers. So what's the secret... Hmmmm. CB750's are stock square-bore engines, kind of the middle of the road. Larger pistons gets you closer to the modern oversquare designs, but then the addition of a stroker knocks you right back down to the original square design.
With these old engines, is it best to just move the power down in rpm by stroking the crank, or is there potential for reliable high spinning power development?
