Undersized pipes?

[Up north rider]

I’m trying to help my brother jet his banshee, but we are coming up short. The banshee in question is almost the same as mine. 
421 driveline assassin. He has paul turner mid range pipes on it as hold overs from his last engine setup (stock cylinder 4mil). We’ve tried so many different jets that we’re wondering if these pipes are just undersized for this engine. 
what are some of your more experienced opinions on this? Also we leak tested the engine. It holds 10psi for 10mins with zero loss, and the carbs are brand new out of the box from redline. 

 

 

[SKEETER]

Talk to bill @ driveline.  BansheeHP on here.  

[T13]

This ^

 

I'm running "undersized" pipes on my big bore stroker and it runs great. Am I leaving hp on the table? Absolutely, but it still runs good.

[Jereme6655]

So what’s the problem? Are you struggling to jet it? Or just curious if different pipes would perform better?

[Up north rider]

21 minutes ago, Jereme6655 said:

So what’s the problem? Are you struggling to jet it? Or just curious if different pipes would perform better?

Both actually. We’re running 35 pwk’s with CEL needle ,and we’ve tried every clip position and mains from about 150-165. I may have even thrown some 148 mains I can’t remember but either way no good. 

[Up north rider]

We checked resistance on all the electrical components. Everything is oem and checks out. 

[Up north rider]

Am I just over looking the 140 range of jets assuming there too small?! lol 

[kawa110]

Lean is mean, but i prefer fat and happy.


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[Up north rider]

57 minutes ago, kawa110 said:

Lean is mean, but i prefer fat and happy.


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I do too! Sometimes we’ll do 50 mile trips into the night so temps and elevation changes quite a bit. I like the buffer of a slightly rich tune. 

[Jereme6655]

I believe the same thing as I ride trail…. Not drag strip. Might wake up to a morning 25 degrees different than the afternoon before. I’d rather ride than worry about if I’m too lean…. 
 

I’d comment about the jetting but I don’t play around with the pkw carbs too often 

[T13]

Regular pwk's or air striker? 

[Up north rider]

Standard 35 pwk’s 

[JerzOutlaw350]

 Are the cylinders ported or unported ? 

[locogato11283]

Driveline really liked Shearers with their 4mm motors.

[BANSHEE HP]

What is doing or not doing? I wouldn't doubt if the jets were 130-140 mains, those pipes are not pulling any rpm or flowing anywhere near what a good pipe does.