Single carb on a twin.

[Walkin_Stick]

Hell yea frog. Buddy of mine used to have a 50 with a 4.5 inch chop in the top. Those things look sick with a short windshield. Find an old rv and yank the 440 and the toqueflite out of it and you'll have a badass ride.

 

[Rocan]

weberkid returns.... youve been saying youll do a dcoe on a honda twin for a year now... do it!

 

[crazypj]

In my experience,
single carb, lower power, higher torque at low rpm because of longer intake.
Generally won't rev out under load as carb should be too small (also, gearing is generally lower
twin carbs, slightly less torque at lower rpm, more of everything at higher rpm
Personally, never seen the point of going from dual to single, if you cant work on two, you can't work on one.

 

[beachcomber]

back in the day Single carbs were for touring - twin carbs for racing [ going fast ].

Virtually every major British manufacturer followed that trend. There was an active aftermarket supply of twin carb manifolds and set ups to convert the single carb. [ twin ] engines.

The benefits of twin carbs [ one carb per intake ] have been stated.

Quite a few folk in the UK have used sidedraught carbs on vertical twins - like the Weber DCOE and the Dellorto equivalent. They look trick and if you apply the logic "because I could" - then 10 out of 10.

That said - most high performance applications I can think of use one throat [ carb / injector ] per intake.

I'm not including US V8's in this - although circuit race versions in the 60's / 70's used 4 x Downdraught Webers [ ie 8 thoats.]

 

[scm]

We should keep in mind that all british twins with a single carb had
360° cranks providing a "symmetrical firing order", i.e. same conditions
for each cylinder.
Whereas Rocan mentioned the Honda twin crank was a 180° one,
causing a 180°/540° firing order, which is unfavorable for a single carb
(e.g. both inlet valves open at certain crank angles).

Best regards
Sven

 

[beachcomber]

Webers / Dellortos were / are regularly used on 4 cylinder car engines with 1 twinchoke carb feeding all four cylinders.

 

[dustywang]

Im running a single carb on my kz400.

Kinda hard to see in the pic. Ill get a better one if you want.

I have a Keihin Pwk 35 running a 140 main jet 50 pilot jet. Runs amazing pulls super hard compared to the 2 carbs. Finding the correct jets took some figuring out.

 

[WeberKid]

weberkid returns.... youve been saying youll do a dcoe on a honda twin for a year now... do it!

I've been busy with law school and havent had time to play. I stated the manifold to do it:

but realized:

We should keep in mind that all british twins with a single carb had
360° cranks providing a "symmetrical firing order", i.e. same conditions
for each cylinder.
Whereas Rocan mentioned the Honda twin crank was a 180° one,
causing a 180°/540° firing order, which is unfavorable for a single carb
(e.g. both inlet valves open at certain crank angles).

Best regards
Sven

and am now planning an XS650 engine project. still keeping the cb450 frame though - but am thinking of frankenbiking it in. I'm surprised anyone remembers me!

 

[speedwobble]

Another side draft resurrection, sorry. But, is it decided that, due to crank design, a Weber DCOE or a Dellorto DHLA side draft carb is not practical, or impossible on a Honda motor? I have a set of DHLAs, and before selling them to a car buddy, I am researching to find out if I can use one on my 1975 CB360..
Any and all definitive input is welcome.

 

[DesmoBro]

there is a member on here shermanator86 he has a pretty badass lil build with a single carb set up on a twin i'll try and find the link......Found It......http://www.dotheton.com/forum/index.php?topic=28708.0


Not really sure what kind of fab would be involved in making it work (havn't seen your carbs)....but it is entirely possible....

 

[canyoncarver]

Kinda reviving an old thread here. I've been searching for a 2 into 1 manifold for a KZ750 twin. Any seen a source for these or interested in fabbing one?

 

[crazypj]

Another side draft resurrection, sorry. But, is it decided that, due to crank design, a Weber DCOE or a Dellorto DHLA side draft carb is not practical, or impossible on a Honda motor? I have a set of DHLAs, and before selling them to a car buddy, I am researching to find out if I can use one on my 1975 CB360..
Any and all definitive input is welcome.

1 into 2 manifold doesn't work so well on 180 degree twins, (eg, CB360) the intake pulses are too close together.
On a 360 twin tends to increase low end torque but you loose top end
I have no idea why anyone would do it though, just getting rid of a carb isn't good enough reason for me

 

[canyoncarver]

The reason I've been thinking of it is mostly simplicity and something different. There are lots of folks doing it for the KZ440's but I haven't seen much other than home made for the 750's. I was thinking of getting rid of the two 34's and just doing a single 40.