Jump to content
Sign in to follow this  

Yamaha banshee big bore/stroking options

Recommended Posts

Ok ive been reading alot on different stroking and boring options and am very confused on all the talk of long rods, short rods, +4mm cranks, +5mm cranks, and blaster pistons. If some one could fill me in a little bit it would be greatly appreciated. I understand a longer rod and bigger piston increases cc's but Im unsure on advantages and disadvantages of some of the stuff. Thanks :bonk:

Share this post


Link to post
Share on other sites

theres a solution to this old post.

You should talk to the nearest fourwheeler junky you can find.

They can usually clarify anything.

Or i can try to throw some stuff at you for a later date

Share this post


Link to post
Share on other sites

The "+" on the cranks refers to how many millimeters the crank will increase the vertical movement ( stroke ) of the piston. On a +4 crank, the piston will go 2mm higher in the bore and 2 mm lower. When increasing stroke, it is wise to use a longer rod to keep the rod angle in check. The longer rod does not affect stroke. That all happens at the crank. At 90 degrees before and after TDC, that +4 crank is causing the big end of the rod to move 2mm more forward and aft of the crank centerline. Too much rod angle causes too much side thrust on the piston skirt leading to premature failure. Since changing the stroke causes so many changes in geometry, you will usually need different rods, pistons, and cylinders to make it all work properly. When going to a bigger bore, the main issue is maintaining proper balance. It's simple enough to make a bigger piston that weighs the same. If you want to build a stroker motor, you might as well get an engine kit that increases bore and stroke from Trinity or Vito's or someone else since they've already gone through the work and expense of blowing up motors to find what works reliably. As for the Blaster pistons, I haven't heard anything on that one. You can use RZ350 street bike motor parts but they generally cost more. Hope that clears things up a bit!

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×