Ok, well that makes sense I guess.
I was under the impression that the Banshee cranks were pretty weak, and that it was not a good idea to push them (the crank) in stock condition. Thanks for the clarification.[img]i/expressions/face-icon-small-smile.gif[/img]

 

anytime sweetheart

 

well there are two sides to the compression story.

on a stock port banshee, bumping up the compression would be a good thing to do because the stock banshee motor doesn't rev the way a small two stroke twin should. when you start building for more rpm though, the higher compression #'s will put a strain on your motor's ability to rev out up top where all the horsepower is at. hurting a banshee's ability to rev is bad. less rpm = less power. the torque gained by running higher compression will offset the loss of rpm some and on most applications, the higher compression higher rpm motor will make more horsepower with the lower compression lower rpm motor. On a drag ported engine that likes to be run at 11,000 rpm though, (the fastest 350 banshees) excess compression is bad. I believe the fastest 350 banshees out there only run in the neighborhood of 150 psi.

with more compression, you are going to have a torquier banshee. great for off the pipe riding. great way to gain more power on stock or mild ported banshees. great for riding a gear high and great for getting off the line quick. bad on the wallet depending on how much compression you are planning on running. bad on the internal parts. the crankshaft will take more abuse with the added strain of compressing the air/fuel mixture in a smaller combustion chamber. running around 160 psi is safe with 91/93 octane depending on your area. 160 psi probably wont even put much more of a strain on the crank than a stock banshee just cause the way they don't rev out the way they should stock.

well that's my 2 pennies.

 

agree with you with the exception of most of the fastest 350's running 150psi in each hole. Remember a small bore short stroke wants to rev naturally, it doesnt need low compression to help it. Bumping it up to 170-190 (if alk) will help get the torque that a banshee doesnt have in the stock stroke/bore setup.

 

I bought my 2000 used and compression was 105 psi cold at sea level in both sides. The general consensus was to do a top end at that time and avoid any chance of piston failure due to loose piston to bore fit. It did run strong at the time with 105 psi and some even advised to keep running until compression dropped to 100 psi. You do not want to run it until it quits before checking compression. After a fresh top end is well broken in, do a compression check for reference. When compression drops 10 to 15 percent, freshen up again.