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thinking of doing a 4mm.


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Have a banshee with 69.42mm pistons. Want to do a 4mm but can I? Since it has that big bore shit done to it would I have to buy stock cylinders or aftermarket ones? Has like 175psi comp. It has trinity stage iv cool head on it and pro circuit pipes.ill need different carbs for sure, just needed to clear up the piston/cylinder problem.thanks in advance.

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Not sure on piston clearance with your bore size and head. I would call Kevin at HJR and ask him what you should do. He does really quality work at a very affordable price and is very friendly. With $1500 he could easily port and put a 4mil in that stock shee. Actually with $1500 you have some options. Give him a call...858-945-3622.

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I would buy some good shocks and a arms and a decent roundhouse swingarm and carrier. A fast bike is pointless if it can't be handled worth a shit.

Also there's more then just a crank and port.

What pipes? Carbs? Reeds? Head? You need a whole package that compliments every other part.

Like stated above trans and clutch need attention too. All this adds up fast if your jumping in with a all stock bike with almost no salvageable parts.

So start with suspension and see how much faster you get.

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everyone says to run it way up there but on gas its a bad idea, anyting over 165 really starts to hammer the motor, there becomes a mark where its un efficient, without an aggresive balance factor built into your cranks its hard to plow through that much compression, and if you arent into a ton of maintenance and totally understand combustion, squish velocity its best to be under 150psi, parts live longer and still make impressive numbers, just my .02.

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It has works dual rates,+6 round house swinger already. it has the cheapo +2 a arms and such.its pretty much ready to go for a better engine.I like the one in it but the porting on it seems to be for drag racing. Because its pretty mild until you get into high rmps then it flys.ill definitely be getting a promod tranny and I already have a lockup and cover from my other banshee.as it sits how could I lower the compression on it? idk very much about engines but I know a little, not much about banshees becides they haul ass and are expensive

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everyone says to run it way up there but on gas its a bad idea, anyting over 165 really starts to hammer the motor, there becomes a mark where its un efficient, without an aggresive balance factor built into your cranks its hard to plow through that much compression, and if you arent into a ton of maintenance and totally understand combustion, squish velocity its best to be under 150psi, parts live longer and still make impressive numbers, just my .02.

Very little of that makes much sense honestly. Just sayin.

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