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Discussion Starter · #1 ·
Ok im putting a 78 CB400A into a mini dunebuggy and id like to swap to a single carb mainly for simplicity reasons and so i dont have to run the factory airbox as i dont believe ill have room without hacking up the box. Ill be able to run an equal length intake and can build my own intake. Biggest question is what size carb? Ill probably go with a round slide unless theirs better options. If yall would like i can post a build thread but unsure what section to put it in.

Also can someone tell me what this broke off sensor is on the block under the right intake? Will it affect how the motor runs?

 

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Messing with the airbox might be a paint, read this, is not exactly about what you want to do but gives you an idea of what you will have to do to change the airbox http://www.hondatwins.net/forums/63-fuel-supply-carburation/23714-cb400-cv-carbs-pods-how-make-them-work.html
So if you want to convert to signle carb you will have to fab some stuff and a lot of try and error will be involved, this means you will put some time into the machine, so why not trying an efi conversion? you are not rebuilding a bike so I assume you are not concerned about authenticity, I looked into efi conversion but it was too time consuming for me, I wasn't willing to figure out a way to make an efi fit into the frame, but you don't have a frame to fit into.
Ecotrons has a "plug and play" kit that might be interesting even if on the expensive side, and I am not an expert since you can't find many in italy but there is something called microsquirt that should be cheaper since it's only the ecu and you can get the trhottle body injector fuel pump ecc ecc from a scrapyard for cheaper than the ecotrons kit
400cc to 800cc Small Engine Fuel Injection Kit
Also, it comes down to how much you want to spend on the buggy but the efi opens up the opportunity for fine tuning at every rpm and maybe a tubro? you can find some for cheap online or at a scrapyard and might be something fun to add.

I think the best place for the build thread should be the "off topic" section or maybe a in the "project logs"

Here is another similar thread might be interesting for you
http://www.hondatwins.net/forums/63-fuel-supply-carburation/29309-2-1-carb-conversion-2.html
 

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The broken sensor is a change switch and to run the motor with out it you will have to change the rotor, stater and CDI box to a 400t.

There is a sticky in the 400 section that will explain it far better than I can.

Bill
 

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Or replace the switch, if you can find one.

Topic moved to "Fuel Supply and Carburation".

There are folks here who can advise as to the best size carb to use. I believe the EFI mod has also been done and I've seen a single carb conversion on the bike. Haven't seen much on how happy folks have been with them.
 

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Discussion Starter · #5 · (Edited)
MikiZed......Fabing up stuff wont be much of a problem. Ive also thought about fuel injection but i think thats a future project as id like to just get this buggy runing and driving atm. Thx for the links. ill read those tonight. Ive read the pod on cv thread several times front to back and infact ive got the shims and jets it calls for i just dont think i wanna mess with two carbs all the time. Ill probaly start a build thread tonight.

Bill H....Thank you for that. The motor cranks up and idles as is but is real sputtery when given throttle and i didnt know how much of that was carb related and whether or not that switch had anything to do with it. I plan on swaping to a GL1000 stator and igntech ignition along with the gm coil.

J-T.....I remember seeing a thread and video on one running on efi but thats all it did was crank up and idle. I also remeber seeing a few on dual to single but i couldnt find them again and also remember reading a discussion on carb size and it seems like it wasnt much bigger than a 30mm but of course now that im ready to do it i cant find those threads lol
 

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Discussion Starter · #7 ·
That was a good read....To bad it just ended outa nowhere with no results as usual :/ I think ill make an intake outa pvc for testing purposes and i have a 30mm round slide carb ill try out to see what happens till i get more opinions on carb size.
 

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BEFFKINGG69 If you remove the change switch see if it has the alum sealing washer under it. The washer should measure .030. if so maybe hang on to it someone with a CB or a Cm 400A could probably use it. Also when you replace it to cover the hole make sure the what you use doesnt go deep enough to hit the shift cam.

Just some thoughts. PS love what your doing. Also the carb boots if you dont use them they are very hard to find.

Bill
 

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Discussion Starter · #10 ·
Thx and I sure will buddy and ill probably leave it in till i find another unless someone wants the washer your talking about. I would like to replace it so i can keep my indicator lights for my buggy build. I found out how hard it was to find boots already lol.
 

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If you dont already know it and you search for a replacement the cm 400s are the same switch, they have a different wire harness but the wires have the same color code so changing the harness is no big deal.

Bill
 

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You'll probably need to go to the GL1000 stator to get enough charge voltage to run the EFI. Stock is only 170W, GL is 300W+. That entails a different ignition system also.
Why are you sizing for 150-200cc, are you going to run dual throttle bodies? Why no O-2 sensor, it provides feedback for mixture control?
 

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Discussion Starter · #15 ·
I meant option 4......I was reading it wrong and seller said only difference between the kits was throttle body size so i see no need for paying almost 400 bucks for the 350-450 when i can get the same thing for 250. The ecu in the kit takes care of spark i just gotta find out if it allows custom tuning of the advance. Single throttle body for now if i go this route just gotta figure out how big. GL1000 stator is in the plans
 
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