Single carb on a twin.
- Thread starter DC74inc
- Start date
should work fine, if anything would work very very well on the honda twins for around town riding as the 180* crank means that when one cylinder isn't receiving fuel the other is, hence there is always a nice vacuum. it will even work with one stock carb thats rejetted, but will run out of steam before high RPMS.
but yes, you will have to make sure intake runners are the same length and all. screw up and you could make one cylinder run lean (rich isn't TOO big of a problem) and before you know it, the piston seizes.
but yes, you will have to make sure intake runners are the same length and all. screw up and you could make one cylinder run lean (rich isn't TOO big of a problem) and before you know it, the piston seizes.
lingo
social pariah
Rocan, I didn't think about the 180 degree crank. The carb size I posted should flow about the same as 2 Mikuni carbs. You would have to go up in carb size some but maybe not as far as I was thinking. Why do you think a rejetted carb would be able to keep up? I would think it would be a little anemic.
well, when one cylinder is taking in mixture, the other is completely closed. so essentially the carb is never doing work for both at the same time.
it would start struggling higher in the rpm range as the time between intake cycles on either cylinder isn't long enough to allow the air redirect/stabilize itself... hard to explain, but in short the mixture becomes turbulent as it tries to move between either cylinder. larger carb helps remedy the issue slightly as you can make the manifold diameter greater leading to a drop in manifold pressure (technically, vacuum), but really this defeats the purpose of having a single carb (from a performance standpoint).
DISCLAIMER: This is all speculative, and works in theory and most likely in practice, but I personally DO NOT have experience trying this on a parallel twin... though I had helped my cousin get a manifold made for a 2 into 1 manifold on his big S&S twin, its a totally different ballgame (to an extent).
i know a while back another member here had run his 350 (or 360?) using only one stock carb... can't remember who? anyway, if i remember correctly his practice of this lead to a similar conclusion that I would expect; nice and torquey, but lacking wide open power.
it would start struggling higher in the rpm range as the time between intake cycles on either cylinder isn't long enough to allow the air redirect/stabilize itself... hard to explain, but in short the mixture becomes turbulent as it tries to move between either cylinder. larger carb helps remedy the issue slightly as you can make the manifold diameter greater leading to a drop in manifold pressure (technically, vacuum), but really this defeats the purpose of having a single carb (from a performance standpoint).
DISCLAIMER: This is all speculative, and works in theory and most likely in practice, but I personally DO NOT have experience trying this on a parallel twin... though I had helped my cousin get a manifold made for a 2 into 1 manifold on his big S&S twin, its a totally different ballgame (to an extent).
i know a while back another member here had run his 350 (or 360?) using only one stock carb... can't remember who? anyway, if i remember correctly his practice of this lead to a similar conclusion that I would expect; nice and torquey, but lacking wide open power.
Walkin_Stick
Miles to go before I sleep
I've seen it done a lot on KZ400's and 440's. Most cats use a Keihin PE 35mm carb from the late 90's CR125's. I won't swear to you that it'll be perfect on your bike, but I've seen it done plenty with great results on the KZ twins. There's a lot of jetting/tuning involved though.
Think T110 and Tr6 single carb Triumph versus twin carb T120. Same size carbs IIRC or pretty close to it and not a whole lot of difference in performance up to the top end where twin carbs do help because the runner is straighter and flows better.
Sudco sells a single carb kit for some bikes and it tends to be a little large, but seems to work OK.
Bigger issues are fabricating a manifold that doesn't hurt performance too much and fitting the whole affair without the carb hitting a downtube.
Sudco sells a single carb kit for some bikes and it tends to be a little large, but seems to work OK.
Bigger issues are fabricating a manifold that doesn't hurt performance too much and fitting the whole affair without the carb hitting a downtube.
DC74inc
Come on in and sit on it.
!yeah! thats sounding amazing. right now im two keihins but damn, a 40 mm mikuni with equidistant intake ports sounds so primo to me for some reason... probably have to do major jetting experiments. ...but if it was good to go i could see that catching on. the bonnevile that it was on was at Trophy Motorcycles in San Diego, a resto vintage shop, and it had a machined alum or steel one into two intake with kind of a goofie wide and flat rounded filter, my imagination went wild with honda applications.
people run them on XS650's
http://cgi.ebay.com/ebaymotors/XS650-two-into-one-intake-street-tracker-ceramic-chr-1-_W0QQcmdZViewItemQQhashZitem3cb944a365QQitemZ260806320997QQptZMotorcyclesQ5fPartsQ5fAccessories
I want to run a DCOE on a twin, but that's different than a typical carb since it's basically two combined.
http://cgi.ebay.com/ebaymotors/XS650-two-into-one-intake-street-tracker-ceramic-chr-1-_W0QQcmdZViewItemQQhashZitem3cb944a365QQitemZ260806320997QQptZMotorcyclesQ5fPartsQ5fAccessories
I want to run a DCOE on a twin, but that's different than a typical carb since it's basically two combined.
joeyputt
The green flag sets me free
Brother the DCOE is a Weber carb, I built a similar system to run dual carburetors instead of four on a inline four cylinder engine, my carburetors are not webers but it is a similar system.
The carburetor has two individual throats, butterflies, etc. that feed off of the same fuel bowl so it is like having two carburetors built into one.
The fuel bowl is off in these photos but they will give you a general idea of what they look like. The first photo shows the engine side of the carburetor and you can see the individual throats and butterflies.
The front of the carburetor.
The carburetor mounted on a custom built intake manifold.
The carburetor has two individual throats, butterflies, etc. that feed off of the same fuel bowl so it is like having two carburetors built into one.
The fuel bowl is off in these photos but they will give you a general idea of what they look like. The first photo shows the engine side of the carburetor and you can see the individual throats and butterflies.
The front of the carburetor.
The carburetor mounted on a custom built intake manifold.
Walkin_Stick
Miles to go before I sleep
Basically a downsized 2 barrel Jeep carb. My tattoo artist put one on his Shovelhead and once we got it tuned it kicked ASS.
Walkin_Stick
Miles to go before I sleep
Frogman- that would be insanely awesome. I've got a metric butt-pile of single barrel Rochesters, Strombergs, you name it. I might give that a shot one day. 
Joey- yeah he ran a little Weber two bbl on a home built manifold. The motor was crazy hot to begin with but that carb really brought it to life. I'll try to dig up some pics and pm them to you if I can find them.
Joey- yeah he ran a little Weber two bbl on a home built manifold. The motor was crazy hot to begin with but that carb really brought it to life. I'll try to dig up some pics and pm them to you if I can find them.
frogman
'74 CB360, '71 CB450, '75 CB550SS
Stick, my first vehicle was a 1950 dodge 1/2 ton pickup with the stock flat-head 6 and a Carter Ball & Ball Single barrel down draft carb. I HATED that bastard until I figured out how to get it tuned, after that it was a BLAST. That mofo maybe this winters project, it's been sitting in my pops shed for 10 years waiting on me.
Link to a pic for those that are interested
http://www.classicpreservation.com/carterBallandBall.html
Link to a pic for those that are interested
http://www.classicpreservation.com/carterBallandBall.html
