from four to two

There is a company that makes such a set up for cb750's. They claim it works good and is a horse power gain. My Hardley ridin' buds think this has gotta be the sh*! for some reason and are always trippin' on how I insist that four carbs are better. I have my doubts about how 2 carbs works better than 4 well tuned carbs. Anyway, I would google CycleX (the name of the company) and try emailing 'em about the tech involved. They seem knowledgable and friendly in general. I can get ya a link if the google search doesn't turn it up for ya.

Ok so i looked into Cycle X and there are doing dual carb setups exactly the same way i intended. with out any problems. Theyre building them for CB750's which share the same firing order. As far as Im concerned the engine doesnt care where the air and fuel are coming from as long as it gets there in the proper ratio. The timing and the valves will take care of the rest.

Ive emailed them to talk about designs. Im waiting to hear back form them now.

Thank you everyone for your input.

This looks real cool any one else thought about pros an cons?

Looks like they are running 1,2 3,4

What is the external jeting they speak of ??


How far off is the spacing of the CB 750
to say the kz 700 or 750 or 650 any of us come close or are we gona have to beg for a one off??


One more and I am done !

Am I the only one tired of buying things in 4? I mean it would be so nice to only have to deal wit two carbs.
Thanks for the thread :woohoo:

Difference in spacing is: kawi 75mm and honda being 76mm (c-c distance between 1-2 & 3-4).

My buddy has the cycle-x mikuni setup you speak of and his bike is a screamer: '74 Honda CB750 bored to 836cc.

Hopefully soon Ill get on prototyping it. im gonna have to pull some brain power from some old timers to pull it off. I might just start with buying the intake manifold used for the cb750's and modify it.

Sham WOW!!!!

Subscribed.


Alot of interesting info on this thread! Can't wait to see some build pics. Reminds me of Chryslers 413 Cross Ram setup.

Different length intake runners will pull different vacuum on the carbs. It is important to remember that the vacuum comes in pulses and the air pressure tries to accomodate these pulses. But air has momentum.

It would not be an issue if the vacuum was constant.

I did small scale modeling of the effects of port volume here. It also shows why a tuned port will get you more CFM with equal vacuum pulses from a cylinder.

I also did an electrical anlog model of it to confirm. (Electricity has many analogs in fluid dynamics.)

It's a lot of reading, though. Scroll down past the manometer stuff to the "further discussion".

home.comcast.net/~loudgpz/GPZweb/Manomet.../ManometerNotes.html

Actually after some careful deliberation, I have decided to run a log type intake with a single carb. This will give me fewer headaches in initial tunning and for future tunning and diagnosing. One carb is always easier to deal with than two or four.

Thank you EVERYONE for their input, advice, suggestions and comments. Its much appreciated.

Itll take some time to get this going but once I do ill be sure to post some videos and pics.

A few year back a member here - biquetoast I think - put a single carb on a 650. Memory is hazy but I think the carb was an SU from a auto. By all accounts it worked very well. Manifold was made from inch and a half copper pipe.

Ive seen a CB750 run the same setup with an SU it worked real well.

I wont be using an Su but most likely stayin with the mikuni, or possibly a Bendix.

In my opinion, the single carb would look much cooler too. An artful manifold will become one of the attractions on the bike.