I was just wondering how you build one? I know you have to get a longer rod. I want to know what kind of power gain I will get from this setup?
Thanx

 

you bore the crank flanges off center the amount you want to stroke the crank, where the rod pin goes through. then you make a bushing to press into the crank flanges that fits the rod pin. i would recommend that you tack weld the parts after you align the crank. you will need to put a spacer under the cly so the piston does not come out the top of the cly. nothing to it if you have a machine shop.

 

Yeah ok, but what kind of power can you achieve from doing this modification, any drawbacks?
thanx

 

The horsepower has a lot more to do with than just stroking the crank (cc's, porting, etc., etc.). Building a stoker engine is pretty serious business. Are you sure you want to go down that road? What kind of riding do you do? You can build some pretty serious power without having to stroke the crank. Give us some details about what you are trying to achieve.

lump-dog

 

A stroker motor and a motor with a long rod kit are two completely different things. You can have one without the other or both together. You can't build a stroker motor simply by puting in a longer rod and adding a base spacer. You will still have the same stroke! By doing this, however, you will have an engine that puts less strain on the rod (less angle of rotation). Some motors will produce better torque with this modification too.
Like the others said, the only way to stroke the motor is by moving the crank-pin (the area where the rod and crank meet) further out from the center of rotation of the crank. If you move it outward 1mm, you will have a 2mm longer stroke. Since stroke is a function of the volume or cc of an engine, stroking gives you a bigger motor. A bad consequence of a stroked motor is that the degree of rod rotation is now increased and the stresses on numerous parts (most notably the rod bearings) is increased. This means a higher likelyhood of failure in these stressed areas.
To help alleviate some of the problems assosiated with a stroked motor, a longer rod can be added at the same time. You then will need either a base spacer or a piston with the rod pivot point positioned closer to the piston top.
Of course, this is all for information purposes only. I definetly don't suggest that you try to make the crank changes yourself and then mix and match parts until you have a combo that works! At least now you have a better idea of what you will be getting into when you converse with your chosen performance shop.

 

I am just trying to learn more about the different setups for a motor, and what takes to accomplish them. I really dont need to stroke my motor but, its nice to learn something new.
thanx for your posts.
peace