bad idea, i know. twin carbs.

so i kinda want to run twin 12mm bings on a cheapo puch kit. not to really go fast or anything, just to do it kinda. i'll go at least 45 or so. don't really care if it's perfect, just rideable. figure i'll make an intake from plumbing parts w/ a T, and two 90 elbows. two carbs right next to each other pointing out the side of the bike. put a T in the fuel line, and rig up some cable system for 2 carbs w/ 2 adjusters.

i'm gonna plan on running the same jets/needles/needle position/slides/airflilters,but something tells me they're gonna be different.

anybody do this? just want to idle and not 4stroke or run lean at WOT. i kinda hope it gets 4 strokey somewhere in the half open range.

Re: bad idea, i know. twin carbs.

You could have them on seperate throttles, maybe the second one on a thumb lever. Using the first carb for better gas mileage you can open the second with richer jetting for higher rpm if you have a big pipe

Re: bad idea, i know. twin carbs.

kinda want to sync them and just figure i have a 17 mm carb. we'll see...

Re: bad idea, i know. twin carbs.

Make it a twin cylinder and run one carb

Re: bad idea, i know. twin carbs.

Jason S.s Wrote:

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> Make it a twin cylinder and run one carb

Re: bad idea, i know. twin carbs.

but i already have 2 12mm bings!

Re: bad idea, i know. twin carbs.

I did all kinds of math on this last year.

Two identical carbs won't get you anything. It will work if you can get them synchronized. There just won't be any performance gain.

For two carbs to increase performance, you need two different sized carbs that are progressively linked. Not easy to do, but there are performance advantages to different sized throttle bodies at different engine speeds.

Re: bad idea, i know. twin carbs.

4stroke but my 84 honda xl 600 has 1 cyl and 2 carbs. same size carbs but diff jetting. the first carb (primary) has idle jet and main. it opens first and has the larger main jet. linkage opens the secondary carb at abt. half throttle. the secondary carb has no idle circuit and smaller main jet.

the bike rips. itll smoke any newer single carb honda xr650 or any other brand 600/650

food for thought

Re: bad idea, i know. twin carbs.

i did some math and figured the area of 2 12mm circles is about like 1 17mm circle. so if the last part of my intake was 17mm, it might seem like a 17mm carb right? idk, i'm a guesser...

Re: bad idea, i know. twin carbs.

Yep.

Re: bad idea, i know. twin carbs.

Just get a cheap 19mm dellorto clone on ebay. It won't just be hard to get the throttle linkages to work in sync, but that T will mess you up. You would need one 17mm pipe coming from the T and two 12mm pipes. Not only will that be impossible to find, but a T has horrible geometry. You want a smooth curved and blended transition, not a 90* angle.

Some more food for thought:

The total flow isn't just based on the total area of the carbs, but also the area of the pipe wall. Think about the flow in a pipe like this:

You will get more velocity in the center if you only have one hole as opposed to two. As the pipe diameter gets larger, the velocity in the center of the pipe can increase.

So just as a recap: two 12mm carbs are not equivalent to a 17mm carb and they will be way more hassle than they're worth. Just buy a cheap carb and call it a day.

Re: bad idea, i know. twin carbs.

Re: bad idea, i know. twin carbs.

Pistachios^

Re: bad idea, i know. twin carbs.

Overpriced Parts /

I ran two 14mm bings with a homemade intake on a puch kit .

Worked fine both carbs had the same jet both opened at the same time .

A mild but noticeable power gain over one 14mm bing only about a mile or so faster but that was prolly due to the pipe. Large Motorcycle throttle, 2 cables, two fuel lines with splitter, two air filters and being cluttered and goofy looking I went back to one bing. Performance was about as good as a 17mm bing or 19mm phbg though

Re: bad idea, i know. twin carbs.

yeah. that's what i'm going for. cluttered and goofy looking. like a rolling junk pile aesthetic. ramshackle sheik if you will...

an e 50 w/ a treat kit or a hero kit is gonna go 45, no matter what kind of shitty carb/carbs i put on it. i got a welder, mapp/oxy/acetylene torches/metal turning lathe. i can do whatever i want really. just trying to build something that will keep up at rallies and look downright silly.

Re: bad idea, i know. twin carbs.

Overpriced Parts /

Go for it. Treats sells a cable with a splitter now .

Things are eaiser now because of Internets stuff

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