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CV 2-1 or New Dual Carbs.......


Nitmare67

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Ok I just had my cylinders ported by Eric Gorr and im now looking to upgrade my carbs. I have 370 mains in my stock carbs and im still learning and fooling with this jetting stuff. I finally have the mains according to the plug chop. I have what most would call a Dune port and my bikes runs great now in the top but I know im leaving alot of the table with the stock carbs. Hell even still has the TORS lol.

 

My question is would I be better off going with a 2-1 or a new set of 28mm or 33mm carbs? Im realling hating this pulling my damned bike apart to jet it. I ride mostly in Hollister which is here in Cali. Most hauling ass on trails, playing on the track, racing down long stretches of road and some rough terrain too. Keep thinking im going to go to the sand "Pismo" but havent made it yet. I'll probley make 1-2 trips a year to the sand most so what do you guys think. This is my current combo

 

 

2002 Banshee

Fresh top end .040 over

Eric Gorr ported mid range - top "dune port"

Toomey T5s

Stock carbs with huge mains lol

Boyseen Dual Stage Reeds

Stock head - Going to do a compression test to determine what size domes to buy with new Noss Head. Not sure what compression im hitting beings exhaust is slightly raisied.

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I changed my carbs to a single 35mm when I put in my +4 stroker (no porting). I loved it! Super easy to change jets, nice clean look, snappy throttle response, and a LOW END! When I got my porting done I added a 2nd 35pwk and kept it that way for 1 weekend. Found that I had too much damn top end for my stock swinger and I really missed the ease of jetting changes. Also the bottom end that I'd grown to love wasn't there anymore. I made myself a new 2:1 manifold to replace the first one I made since it had a few design flaws. Just finished putting the single carb back on and I'm taking it to the dyno next week for tuning and to see what kinda numbers I'm pulling.

 

So I guess what I'm saying is: I love having a single carb, but they're not for everybody. You're going to lose a little on top, but you'll get it back down low. Most single carb guys ride mostly trails and everybody says for strictly sand to go with duals. Well I ride glamis 99% of the time and I say that its really personal preference and I'll keep my single thank you.

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I'd ask eric gorr, since he ported it and will know exactly what size carb will work best for your setup..plain and simple, otherwise you'll be spending hundreds of dollars in carbs and still won't have All the hp you should have..

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hey man. i run a 35mm carb with the trinity setup and i love it. i don't notice any real loss on top although i'm sure i might have lost a little. i plan on porting to really wake her up cas right now i have NO bottom due to high compression and the shearer pipes i'm runnin, but i love the hard hittin powerband. i would say don't knock it till u try it. if u can get a used setup try it and if u dont like it u can always sell it. my opinion is that the twin carbs aren't reeally necessary unless ur strictly drag. my bike runs great with the single carb. and is a little better on gas too. hope this helps. feel free to ask me ne other questions. dunedemon and some others have some nice banshees with the setup as well and they ride dunes all the time.

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Ive been doing a ton of reading on her about the 2-1 setup and it seems like almost everyone thats running it loves it. Ive became really frustrated trying to jet these stock carbs. It such a pain in the ass everytime having to pull the bowl and all this crap to get to the mains. I just realized that all the pwk carburetors have the plug in the bowl though that alows the main jet to be changed without removing the carburetor which is a big plus for me. All this TORS junk on my bike is also irritating. I figure I'll leave a bit of top end power on the table with a 2-1 but for racing down trails and hauling ass the 2-1 will probley be better for me. Either way im sure it will provide more top and bottom power than the shitty stocker carburetors right?

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Yeah it'll definately improve the bottom end. You might lose a little on top but it won't be much. Changing the main is about a 2 min job. Just loosen the clamp, rotate the carb. Use a 17mm on the nut, a 6mm on the jet, put it back together and ur done. Don't even have to pull the carb or filter off the bike.

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How would a single 35 compare to dual 28 pwk's. Do all pwk 28s have the flat slide or whatever? I notice the carb tops in the pictures look different than the round screw on type. Will 28's work with the factory intake manifolds? Im sure these would be easier to jet beings i can still make needle changes without taking the tank off and main jets changes without pulling the carbs. Thats already a big improvement over the stock pain in the ass.

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I bet anything you won't lose any top end over stock carbs if you're jetted right! Now w/ dual 28's, I'd think it would be a lot closer. And I remember seeing a dyno chart that showed 30 mm's pull longer than a single 35.

 

Plain and simple, if you are looking for easier jetting, you will be more than happy with the 2 into 1 set up. I've got Eric's "Woods" port and a single 34 mm PJ. I couldn't be happier with the way she runs. I mostly ride MX, trails, and open fields.

 

Call Eric and see what he recommends...

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You will lose a little peak power w/ the single, so if you can handle that, then no problem...As for the size of the carb though, you really have to ask Eric...I've done a lot of dynoing w/ 5 different size carbs on my stroker. The bigger the better, BUT!!!! when I did my stock shee w/ just Pt mids and heads, the stock carbs pulled the best hp....even ported stock carbs lost 2hp across the whole curve...I'm sure a mild porting would probably like the 28's, and a drag port would like even bigger carbs, but your guess is as good as mine..w/ my research, you could gain very little and lose a lot if you don't have the right size. I've also noticed that too large of a carb will make jetting extremely hard to dial in since your over carbed and don't have enough air flow (velocity) going through the carb to make it work efficiently....Eric Gorr is very reputable and I'm sure he can take out a lot of the guess work for his porting..

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