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Banshee Porting


4stroker

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Hi guys, im from australia so dont have access to a heap of good banshee tuners like you guys do! The guy i want to build my motor is an old two stroke guru, sets up all the best cr500s for the finke desert races, and has done a few banshees as well for the desert race but freely admits to not being all that familiar with them.

 

anyway i explained to him that i want to flattrack/speedway race my quad but also keep it fairly reliable and tame enough to trail ride/play ride.

 

this is what he reckons he will do to it...

 

"The exhaust ports end up just a little higher, mainly to get a better flowing entry into the passage, and wider for more area, the transfer ports all get raised, reangled, and widened. The reed faces on the barrels are machined to raise the c/case compression, and the head machined as previously discussed.(Machine head face,squish,chamber on std head) Case matching is not really worthwhile.

This will not make it peaky and will certainly fatten up the power curve"

 

what do you guys think? the quad currently has fmf fatty's and power core 2s, k&n filter with adaptor plate, and i want to run either pwk 28s or 33s, not sure what size to go with. also will advance the timing by 3 degrees and run on 98ron fuel or better.

 

what compression ratio should we aim for? will probably be first oversize wiseco pro lite pistons.

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If you don't feel comfortable sending it to that guy, send it off to someone here in the states. There are plenty of well known builders here. You got to pay for shipping both ways but atleast you know they are going to do it right. With porting I would go with some 33's, and a Cool Head to get your comp to like 165, that depends on elevation also. +4 timing would be good.

 

Hope that helps. :thumbsup:

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Sounds good, buddy. If he tuned banshee for desert race, I think he know alot on durability.

He souldn't raise to munch, and you'll have a good port timming and duration. radiius is a simple way to have a better flow.

 

You should be happy with it.

 

Maybe you can ask him for with RPM range he will tune.

Edited by !TWISTER!
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thanks for the replies guys he is a very capable man so it should all turn out sweet.

 

what does a stock banshee with pipes and filter rev to anyone know?

 

 

with fmf fatty pipes on a stock port youd probably only be close to 7700-8000 rpms before it falls off the pipe and peters out .after porting and timing advance of 5 degrees ive seen 1000 rpm rise for them and 12-14 more hp with like 6-7 more pounds of torque its a vague description he gave but it sounds as though your builder is on the right path ,a popular port spec i have found that works great for all around play ripping with excellent lowend and broad midrange is 18cc domes with fmf pipes is 192 degrees of exhaust duration and 126 degrees of transfer ,equaling 33 degrees of blowdown ,exhaust port 70% chordial width with a large arc on the roof and keep transfer widths small and reangle the rear transfers directly towards each other .id run these port specs by him and ask his opinion .fmf kinda suck for over 9000 rpm,but they make really nice broad torquey power for all around fun IMO ,with that port you should be able to hold a 2foot high power wheely through first 4 gears with front wheels never touching the ground .

Edited by rocketboy
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