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Fuel setups on the 421 Cub?


Lethaface

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Hey guys. had a few questions running into my mind while doing a search.. I have been doing a frame up build on my 99 banshee since about september.. I have been buying parts week to week and just slowly getting it all together..I have made sure to get all the common must haves like the longer swinger, Barnett clutch with toomey springs and even went as far as replacing all Bearings, seals orings, and even the Flywheel key and keyway..

 

So, my new 36mm TMX carbs came in last week and it's got me wondering if my stock petcock is going to give me enough fuel..In case it matters i'm running 110 octane with 17cc domes..My big concern is running the bowls dry on long straights.. My riding basically consists of fire lanes and i'm gonna try and hit the local 1/8th a couple times a month.. I've read a little bit about people using fuel pumps but wasn't exactly sure how that would work on the banshee..I've also read a few mixed reviews on the pingel..If a pingle is needed would it need to be used in conjunction with the fuel pump?? If there needed i don't mind at all delaying the completion by a paycheck or 2 i really just don't wanna blow it up on it's debut date lol..Any help is much appreciated

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How long is a long run? I ran 35PWKs on mine, with a power jet...never came close to running out of gas....

I think you should put a powerjet on them, then a fuel pump....that way when you jump to alky, all you gotta do is drill the carbs...LOL.

 

Seriously, you should be fine. Worst comes to worse, remove one of the floats in each carb....

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is it me,but 17cc domes are for alky right,i mean the cub will run on 17cc i know that,but not as reliable,atleast thats what i was told by the BIG GUNS.gas just gets to hot .............. :banghead: :banghead: :biggrin:

just remember elevation plays a big roll.iam in cali so maybe the smaller domes only apply to the guys that are at sea level. :thumbsup:

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Thanks guys.. I would run alky but honestly there is no place i know of to get it here..The nearest speed shop to me is probably 120 miles away..Just to put it in perspective for you guys, the fastest atv in this town that everybody always tell's me is going to beat me is a Honda 450R thats piped/cam'd..People are more into mud here i guess..When i took my cub and crank to the local shop i felt like i was delivering Fire to the first cave men lol..They were in ahhh to say the least.

 

Dave, A good run honestly varries..I'm thinking the most would be a mile becuase some of the firelanes are pretty long/open..Of course all of that mile isn't with the throttle pinned or anything but there is alot of open spaces..So probably a honest guesstimation would be 1/4 mile pinned at the very most

 

As far as the domes i am at 2,000 feet elevation, so if i'm not mistaken thats at about 185-190lbs of compression..Majic performance warned me about them so if i end up with to much compression then i'll go to a 18cc dome.. My last motor was a dune/drag port, stock stroke with 17cc domes and by the time i was done i ended up with 175lbs of compression..My mistake buying the 17cc domes this time for the cub is i didn't take into acount the bigger piston and longer stroke making more compression..I'm hopeing that with only the 4degree timing advance and running the 110 detonation won't be a issue..

 

 

So Dual Feed pingel should be sufficent??

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I ran 185PSI and a ton of timing on my cub, you'll be fine with 110.

Pingel might not be a bad idea if you're going to hold it wide open for 1/4 mile...

 

The problem with fuel pump is you can't just run 'em with normal carbs...you need to have carbs designed to run a fuel pump, the needle and seat are totally different. (It's what I got for my 10 mil running alky)

 

I'd say remove a float for more volume, but...if you put a pingel and remove a float, you'd definately be safe on gas.

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Hey thanks alot for the help dave..The pingel is gonna have to wait a few weeks till i can budget it a little better..I just wanted to get all my eggs in a basket so i wouldn't have any issues after its all together..I think now everything is pretty much covered!! Anyways thanks for the help fellas..

 

Jeremy

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