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The perfect Pipe for a 421 68mm bore, +4mm stroke. ?


EvilBanshee

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Hey guys, i want your opinion of the best pipe for my set up. Its a 421 with FMF fatty's and I feel like my quad is just starting to get into its sweet stop up high then it stops pulling. I think my Pipes are restricting my quad. I do open riding. Alot of drag racing. Dont get me wrong my quad pulls good. But if i let it rev out its like someone lets off the throttle. I know their is alot more in this thing. Its jetted perfect. I have 34mm Keihlins on it. It has to be the pipes. I have tried everything with the fuel lines to get zero restriction. I still want alittle mid range. But i would prefer a more top end pipe.

Edited by EvilBanshee
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i assume ur talking about a cub or a serval maybe? Well depending on budget shearers are my favorite, id like to try snipers someday but idk lol, if you still want some mid and wanna hit that top end try some cpi's. Also if its ported i would ask who ported it what the durations are set up for it u ported it for the fattys (heaven forbid) then it may run better than a pipe thats not set up properly. then again im just pretending like i know something so dont strickly go by my suggestion.

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The Company i bought the engine kit from said in frame Big bore Shearer's would be perfect for my engine. Me and my Builder did very mild clean up to the port's. We just made it "More Efficient" as he said lol.

Any body have any idea what a set of Shearer's are worth? like 600 bucks?..

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The Company i bought the engine kit from said in frame Big bore Shearer's would be perfect for my engine. Me and my Builder did very mild clean up to the port's. We just made it "More Efficient" as he said lol.

Any body have any idea what a set of Shearer's are worth? like 600 bucks?..

 

 

550.00 for raw shearers and you want small bore pipes,not big bore.

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big bores as i understand were developed for the 535. smalls were for smaller motors.

 

id look into small bore inframe shears. if you want more of a "dune/ low end motor try the snipers.

 

on my rider stocker 421 i run trinity inframes they have a nice mix of both.

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No one has mentioned the R-2's? I am building a 421 right now and have been reading around and it seems a lot of people are loving the r2's for their great mid range that keeps pulling much higher than the mid range pipes. I have yet to see a comparison between the top suggested pipes on the same engine though such as: shearer SB inframes, CPI, R2's, and Snipers. shrug.gif

 

When you consider the banshee being a twin, 68mm bore per cylinder isn't that big. Probably why the SB's are suggested mostly.

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Alright ill look into a set of small bore Shearer's or trinity's. I do have another question, Im a V8 guy. Changing the pipe to a shearer or trinity from FMF's, Will this throw all my jetting? If so how much? A jet size or 2 bigger or so?? Orr will i just bolt on and go?

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Alright ill look into a set of small bore Shearer's or trinity's. I do have another question, Im a V8 guy. Changing the pipe to a shearer or trinity from FMF's, Will this throw all my jetting? If so how much? A jet size or 2 bigger or so?? Orr will i just bolt on and go?

 

Depends how spot on your current jetting is. Might bump it up a main. Just go ride it and see how it responds really.

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