more stroker quesions...

[wildman326]

I've been told by people in the know that strokers have one REAL bad side effect.

Their owners quickly become addicts.

Maybe it's like crack.

 

[cookerq62]

I know longer rods put less stress on the sleaves, but what else do they do? Do they slow down the piston speed or affect torque because of the different geometry between the wrist pin and crank? just curious

 

[Mile9c1]

I know longer rods put less stress on the sleaves, but what else do they do? Do they slow down the piston speed or affect torque because of the different geometry between the wrist pin and crank? just curious

The longer rod (same stroke) will have longer dwell time at top dead center and bottom dead center. I don't know if that's good or bad, but they say that with longer rods you get a wider powerband and more RPM's.

Think Kawasaki 750 vs. Yamaha 701.

 

[Mile9c1]

I don't think you need longer rods unless you go with an 8mm stroker. I have a 6mm stroker and the piston skirts nearly contact the crank. Almost every 5mm and 6mm stroker that I've heard of used stock length rods.

 

[Crab]

I don't think you need longer rods unless you go with an 8mm stroker. I have a 6mm stroker and the piston skirts nearly contact the crank. Almost every 5mm and 6mm stroker that I've heard of used stock length rods.

My question is, when you use say a 6mm stroker crank, the piston is 3mm higher and lower than stock with stock pistons. Do you have to raise the entire cylinder by the 3mm and use an extra thick special spacer to keep the port timing in check? That seems like it would allow more transfer porting to the bottom of the port. Or do they run custom pistons that have the pin location moved?

 

[Mile9c1]

My question is, when you use say a 6mm stroker crank, the piston is 3mm higher and lower than stock with stock pistons. Do you have to raise the entire cylinder by the 3mm and use an extra thick special spacer to keep the port timing in check? That seems like it would allow more transfer porting to the bottom of the port. Or do they run custom pistons that have the pin location moved?

There are many options, like we said above. You can raise the cylinder, but you don't have to. I have a 6mm stroker and it doesn't use any spacers; the domes have been custom cut to allow the piston to travel upwards those extra 3mm.

 

[Crab]

There are many options, like we said above. You can raise the cylinder, but you don't have to. I have a 6mm stroker and it doesn't use any spacers; the domes have been custom cut to allow the piston to travel upwards those extra 3mm.

So in your case, the rings don't quite make it to the head gasket? Did you do any porting lower to maximize the incoming charge? I had wondered about stroking a 650 kaw with a 750 crank, or 650 crank and modded 750 cylinder. Supposedly that works good but required some machining of the cylinder.

 

[robertg]

I know longer rods put less stress on the sleaves, but what else do they do? Do they slow down the piston speed or affect torque because of the different geometry between the wrist pin and crank? just curious

I think a longer rod has less stress on the crank and wrist pin also. At 90 and 270 degrees you have less of a rod angle.