single carb setup,is it possible?

[crazy steve]

If you do this, one thing to watch out for is the operating tempature of the individual cylinders. If you have different runner lengths to each cylinder, you'll run into rich/lean conditions between them and you can cook one cylinder while drowning another; this is why a carb sync is so important. This is much less of a problem on water-cooled motors as they have better/more even temp control and aren't nearly as sensitive to this.

'78E original owner

[joceiphus]

I plan on putting a turbo on one of my XS1100's, so I AM doing research.)

How's the research coming?

[joceiphus]

I'm probably wrong, but I've heard that the first Honda Civics were just a motorcycle engine turned sideways. What did they do on those?

[crazy steve]

I'm probably wrong, but I've heard that the first Honda Civics were just a motorcycle engine turned sideways. What did they do on those?

The real early Civics used a 600cc opposed twin (maybe it was 660; too long ago..) that was basically 1/2 a VW motor. But if you look at any air-cooled multiple-cylinder motor with a single fuel point, you'll find that intake runner length will be equal (or very close).

'78E original owner

[79XS11F]

I don't know why you would want to go to a single carb setup. Part of what makes these bike produce the power they do is the 4 carb setup. By the time you get a single carb set up you could have bough all the necessary fine tuning tools one would need to get the 4 carbs running sweet.
Rob

[Ivan]

Hi,
I've seen Webber side drafts used for what you want to do. Check their website for pricing. I think they'll be expensive though.
Regards,
Tdog

They are damn expensive. I think they have a platinum-gold-titanium alloy in them somewhere. BUT you can find them in salvage yards on old Suzuki Sidekicks and the Geo equivalents at decent prices. And like I said, there are lots of parts still available and the tunability is pretty high. I think the model that would have worked when I was frustrated with carbs was a DATRA, but I can't remember. I had a FIAT with a little Weber on it, which was about the only thing on that car that never failed.

[fredintoon]

is there anyone who did a single carb setup? This is pretty cool,no more synchro of those 4 carbs,you're just left to mind that single carb...

Hi Paul,
working on my sons' V4 Hondas with their 4 carbs intertwined in a horrible knot, I used to think, "What this thing needs is a manifold anna downdraft 4-barrel!"
While a simple cast manifold would allow a single side-draft carb, as has been posted, getting the manifold to flow right would involve using a flowbench on the prototype. Mind you, once it's right, it's right. No more fiddling adjustments to be made.
How about going with fuel injection instead? Typically, FI cuts fuel consumption way down which would be a real bonus, especially at the price of gas in the Philippines.
Even at the Canadian price of $0.96/litre my XS11 rig at the same fuel consumption as the family Buick is NOT an economic mode of transport.

[paulbaut]

Hi Paul,
working on my sons' V4 Hondas with their 4 carbs intertwined in a horrible knot, I used to think, "What this thing needs is a manifold anna downdraft 4-barrel!"
While a simple cast manifold would allow a single side-draft carb, as has been posted, getting the manifold to flow right would involve using a flowbench on the prototype. Mind you, once it's right, it's right. No more fiddling adjustments to be made.
How about going with fuel injection instead? Typically, FI cuts fuel consumption way down which would be a real bonus, especially at the price of gas in the Philippines.
Even at the Canadian price of $0.96/litre my XS11 rig at the same fuel consumption as the family Buick is NOT an economic mode of transport.

Hi there fred! Ur right FI will be a great bonus...we are really thinking about that too.but for now,we are looking for the right carb for this project....we hv been tinkering with a carb of a jetski that is lying around the shop...i will keep u guys posted then..tnx man...-paul

[crazy steve]

...Part of what makes these bike produce the power they do is the 4 carb setup....

Rob

That's not really true. These have what they have because that's what 'packages' into the available space the best. If you could manage a good intake manifold design with a properly-sized single carb, you could probably get more power out of these motors. The OEM 4-carb setup is rather inefficient and is the main reason for the not so good fuel economy of these bikes.

In theory, just one carb the same size of one of the OEM ones should be large enough to feed the motor, but in practice you would probably need one 10-20% larger.

'78E original owner