Moving the power band.

[vizmark]

I installed a new top end on my wife's banshee this winter and we finally got it out to Coos Bay this past weekend. It ran great with more power than before (stock cylinders/bore). We like to trail ride and hill climb through the trees. With this set up the power band comes on too high (late) in the rpm band and is short. So it doesn't work real well with our riding style. The porting job that was done to the cylinders I was told was more of a clean up and smooth out.

 

How can I lower the power band and make it wider?

[majorcr3]

who did your porting?

[lms1977]

most will tell you they suck but the 2 into 1 pipe works for me in the woods and add some compression to it that will help some.

[lms1977]

also if the exhaust ports were raised much more than 1 to 1.5 mm low end power will be decreased.

[vizmark]

who did your porting?

 

I don't know. They were ported prior to me buying them.

[Larry's Shee]

Are these cylinders new to this build? I see in your sig that you have Vito's pistons, are they the ones with a cut-down on the exhaust side on the crown?

[vizmark]

Are these cylinders new to this build? I see in your sig that you have Vito's pistons, are they the ones with a cut-down on the exhaust side on the crown?

 

Yes, the cylinders/pistons are new to the rebuild. Yes, the pistons have the cut down on the exhaust side of the crown.

[newbatv]

just install new gearing, that moves the powerband down.

[Hibnecker1]

just install new gearing, that moves the powerband down.

x2 lower a tooth on the front sprocket or go with smaller rear tires

[spurdy]

x2 lower a tooth on the front sprocket or go with smaller rear tires

 

 

You're kidding, right? Adjusting your gearing changes the *speed* you are going when you come into the powerband but does nothing for the time the powerband hits in relationship to the RPMs of the motor. This is primarily controlled by the exhaust pipes. Drag pipes come on higher and mid pipes come on lower. However, everything works together as a system. The bike has to be built around the kind of riding you are going to do and how you want it to perform. It's kind of like a cake recipe, fuck up and put the wrong ingredients in and you wind up with something not so much like a cake.

 

SP

[vizmark]

You're kidding, right? Adjusting your gearing changes the *speed* you are going when you come into the powerband but does nothing for the time the powerband hits in relationship to the RPMs of the motor. This is primarily controlled by the exhaust pipes. Drag pipes come on higher and mid pipes come on lower. However, everything works together as a system. The bike has to be built around the kind of riding you are going to do and how you want it to perform. It's kind of like a cake recipe, fuck up and put the wrong ingredients in and you wind up with something not so much like a cake.

 

SP

 

SP,

The gold series pipes I am running were great for a mid range power band when I was using stock pistons/bore. I changed to vito pistons, cylinders with a very mild porting, coolhead, reeds, and +4 timing. Although she hauls butt, the power band recipe as you say got messed up for my wife style of riding.

[mikechief]

you have to much sugar in your cake man ! Get rid of the pistons . Those pistons raise exhaust duration , if you have some porting done youmight have a drag motor

[vizmark]

you have to much sugar in your cake man ! Get rid of the pistons . Those pistons raise exhaust duration , if you have some porting done youmight have a drag motor

 

mikechief,

Can you explain more about the pistons issue and exhaust duration? Is it because of the tapered ends on the exhaust side of the pistons? When I bought them they raved about a 8hp increase, which I got. (seat of the pants feeling anyways). All the new power though is is in the high rpm power band. The power band window seems to also be very short. Almost when it hits, its time to shift.

[mikechief]

those pistons are a poor mans port job . If your cylinder are also ported ...you have 2 port jobs worth of exhaust duration . Which will do what you are saying

[WINDYCITYJOHN400]

Those pistons work great if you don't have porting. But if they are ported cylinders....then you just doubled the extent of the porting. So YES. You now have a serious drag port. You'll have to go with a standard Wiseco piston. (Don't get the Vito's stock style replacement pistons, they aren't good at all.) The Vito's Super Stock pistons are a great item....but just aren't a good fit for your build. Sorry....looks like your going to be swapping some slugs. Maybe you can find someone without any porting who wants to see big HP gains on their next re-build.