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Discussion Starter · #1 ·
i got a 24mil bb twister and the guy i got it from had 38mm carbs on it and it killed the power so im gonna upgrade to a bigger set and was wondering what you guys thought would be the best,,i was thinking 48mm lectrons or maybe 44's and have dennis bore them to 45mm..anyway do you guys think the 38mm carbs hurt the power on the motor?..
 

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QUOTE (tripledsracing @ Dec 3 2008, 02:18 PM) index.php?act=findpost&pid=18357i got a 24mil bb twister and the guy i got it from had 38mm carbs on it and it killed the power so im gonna upgrade to a bigger set and was wondering what you guys thought would be the best,,i was thinking 48mm lectrons or maybe 44's and have dennis bore them to 45mm..anyway do you guys think the 38mm carbs hurt the power on the motor?..
48mm lectrons from packard are your best bet
 

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hmm i have 38/40's on my stock cylindere'd 350cc alky motor. i'd say the biggest carbs you can find a 24mil is HUGE>
 

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I'm going to say YES those tiny carbs killed the power. I have 41's on my 14 mil. I'm about to upgrade to 44's. That should help you out.
 

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That is a very good carb that you had though, and I bet it was a breeze to tune!

The bigger (48's 50's) will make more hp, especially on the dyno. But they will be more difficult to tune. I think a 48 would be a good choice for you.

Not sure why Eric sells the 44's for the same price as the 48's. They shouldn't be the same price.
 

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Discussion Starter · #8 ·
k..what about my compression about were should it be at?..i was thinking around 190-200psi?..im also going 80mm bore im at 78mm right now,that should bump my comp up but i dont want to much do i ?...
 

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Something in the 44mm range would be good. As some have mentioned a good balance between a carb that is easy to tune and still will work well on the top end.

As for your compression. Maybe I'll be a bit frank here and perhaps even a little pointed. You have a $10,000 motor, now is not the time to start taking short cuts on set-up. You really should know what compression RATIO that motor is. To me there is an apparent absence of any knowledge of the configuration of that motor- thats not necessarily a bad thing if you had professional engine builder do all the set-up for you based on their testing and proven outcome. But when its bad is when someone buys a motor and starts making changes without even knowing where they are starting from.

Its the cutting edge of Banshee performance currently and its not your average 350 duner. As such you need to make sure your set-up is correctly done in an effort to prevent a catastrophic failure. Head geometry is crucial to that- with that much bore and stroke there is little wiggle room to get it wrong. You must know what the compression RATIO is- such a large motor will typically not tolerate much above 15:1(gas) & 16:1(methanol). If you start jacking the compression around to try to establish some mythical PSI reading- you may very well wind up with a failure. The massive stroke and bore of that set-up will need to have increased squish clearance, reduced MSV values, and a moderate compression ratio. Get on Ebay and find a burrette tube. Then. Many thanks to one of my mentors Howard Richards of RED- here's a nifty link to an article on how to calculate your UCCR:
http://www.sacoriver.net/~red/uccr.html

That much bore and stroke will make plenty of torque- risking $10K on trying to squeak another few HP out of it by putting it on the edge of detonation with a high and perhaps even unknown compression ratio......
 

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QUOTE (Backcountry @ Dec 17 2008, 09:43 AM) index.php?act=findpost&pid=21100Something in the 44mm range would be good. As some have mentioned a good balance between a carb that is easy to tune and still will work well on the top end.

As for your compression. Maybe I'll be a bit frank here and perhaps even a little pointed. You have a $10,000 motor, now is not the time to start taking short cuts on set-up. You really should know what compression RATIO that motor is. To me there is an apparent absence of any knowledge of the configuration of that motor- thats not necessarily a bad thing if you had professional engine builder do all the set-up for you based on their testing and proven outcome. But when its bad is when someone buys a motor and starts making changes without even knowing where they are starting from.

Its the cutting edge of Banshee performance currently and its not your average 350 duner. As such you need to make sure your set-up is correctly done in an effort to prevent a catastrophic failure. Head geometry is crucial to that- with that much bore and stroke there is little wiggle room to get it wrong. You must know what the compression RATIO is- such a large motor will typically not tolerate much above 15:1(gas) & 16:1(methanol). If you start jacking the compression around to try to establish some mythical PSI reading- you may very well wind up with a failure. The massive stroke and bore of that set-up will need to have increased squish clearance, reduced MSV values, and a moderate compression ratio. Get on Ebay and find a burrette tube. Then. Many thanks to one of my mentors Howard Richards of RED- here's a nifty link to an article on how to calculate your UCCR:
http://www.sacoriver.net/~red/uccr.html

That much bore and stroke will make plenty of torque- risking $10K on trying to squeak another few HP out of it by putting it on the edge of detonation with a high and perhaps even unknown compression ratio......
you wont win planetsand that way.....
 

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Discussion Starter · #19 ·
thanks for the info backcountry, also louie at twister done the motor and im gonna send the motor to him and let him decide on what to do,if he says to go 80mm bore thats what we will do..but on the carbs im working on a set of 48mm wk billet carbs so thats gonna be the carb im gonna use,but one thing has me confused is why louie would put a small set of carbs(38mm)on such a big motor?..would anybody have an explanation to why?..it still dynoed over 150hp on motor!..
 

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because there is still to much metal in the port tunnels....the billets have in them that can be took out then you can go to some bigger carbs
 
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