TOPIC:

Just got to thinking about the possibility of only having two larger carbs opposed to 4 smaller ones. It seems to me that it could work if you made an intake manifold with equal length runners for each cylinder, make two cylinders turn out to one side...and the other two turn out to the opposite. Put a flange on the end to mount the carb and have a small filter for each carb. Kind of like a cruiser bike...only with one on each side.

Just hashing this over in my head, seeing if you guys think it would be do-able. It would be kind of a neat one off thing to do, plus you could use newer...easier to come by carbs and only having to deal with two of them. Seems to me that two cylinders sharing a carb wouldn't hurt anything as long as the carb had a big enough bore...v-twins do it.

Maybe i just have too much of a creative imaginiation...its what happens when i have tubing laying around. The old tater gets to clickin.

Anythings possable. Milkman did something similar on his 4 cylinder, using only one carb though and piping. His bike runs well with the set up.

I just did a spark plug check last week after 3600 miles. All four were a nice tan. There was no sign of lean burning on the outer 2 as someone here mentioned that they thought would be a problem.
I had it out on 95 today and used that for the speed limit for a couple miles, that was fast enough for me. , .
I am pretty happy with the outcome of the experiment.
Ride Safe,
Les

kz1300's did it from the factory. used 3 big carbs instead of 6 little ones. by the way milkman, nice job!

Thanks, arobsum. I appreciate that.
Ride Safe,
Les

Anythings possible. Here a link to a twin carb set up for the CB 750

www.cyclexchange.net/Carb%20System%20Comp%20Page.htm

Fish

Thanks for the info, atleast now i know its atleast been done before. Only thing to figure out now, would be what size carbs one would have to use on a dual configuration. I imagine the linkage would take a little bit of imagination as well.

What size carb is that on the previous single carb setup? I don't think i've ever seen a carb like that before.

Torch it's a 1.5 inch Zenith Stromberg off a Triumph 1500 british car. I have another one off another british car that had a 1300 cc engine in it. This on has an adjustable jet that is adjusted from the bottom of the fuel bowl, whereas the one I am using now has an adjustable needle that is adjusted down through the top of the diaphram spindle.
I am going to test that one to see if it works even better. I figure that my 650 revs probably twice as fast is a car would so it may work more efficiently.
They did make versions of this carb that have a 1.25 bore which are hard to find and one with a 1.75 bore which are on ebay all the time.

Ride Safe,
Les

LOL that may be why i've never seen one before. I've heard of strombergs but never seen one. Im kind of wondering how much carb it would take to run a dual setup.

the concept works, milkman's bike is testament.

i think of it this way, i run a mikuni hsr-42 mm carb on my 1075 turbo engine.

if that single carb can move enough fuel to keep a 1075 with 9psi of boost happy, then it would be quite content running a bike with no turbine.

what would the drawbacks be? not many that i could see. you might lose a little bit of throttle response, but you will not have to balance carbs, the longer intake runners should contribute to some lower end torque, jetting will involve ONE carb vs. 4... the list goes on.

i should just try it. i could use the turbo manifold with a silicone coupler... just fire it up.

hmm.

--r

I thought about maybe trying a 40mm or 42mm carb instead of a duel carb setup like described earlier. The linkage would be a nightmare to design if they were not mounted side by side.

My main reason for even pondering this would be like you said, easier tuning and jetting. Plus you could use a carb from a later model bike...and have parts falling from the sky. I still don't know which direction im going to go, a total rebuild and tune is going to cost me around $280 and then i still have to deal with 4 carbs. I've got the tubing and plate to make a pretty decent equal length intake manifold, so basically all i would be out would be the cost of a BIG carb. Which i haven't really checked to see what the prices on one of those would cost. I might give this a go.

A single carb would probably go a little bit better with the bobbed drag bike look im going for.

This is a fascinating topic to me you guys. Let me know how it comes out.Here's a mikuni 42 mm with manifold adapter and air filter..something like that perhaps?
cgi.ebay.com/ebaymotors/Mikuni-carb-42-c...QQrdZ1QQcmdZViewItem

Post edited by: pumps, at: 2006/08/07 00:28

Post edited by: pumps, at: 2006/08/07 00:28