single cylinder twin carb?

[Harri]

Hi all. My xf650 single cylinder has twin 32mm mikuni carbs. Is there any particular reasoning behind twin carbs on a single? Wouldn't just one carb suffice?

Batcud

[Guest]

Hi all. My xf650 single cylinder has twin 32mm mikuni carbs. Is there any particular reasoning behind twin carbs on a single? Wouldn't just one carb suffice?

Batcud

 

I think you'll find.. if you look hard enough, that the earlier engines that yours was a development of. had single carbs. and it didn't work very well.

[mattycoops43]

'MORE POWAAAAAAA'

[megawatt]

One carb per valve will give slightly more power, theoretically.

[Grumpy Old Git]

One carb per valve will give slightly more power, theoretically.

 

But only if balanced correctly.

[Fozzie]

One big carb isn't as efficient as 2 smaller ones basically.

It's a long explanation involving atomisation, the distribution of the fuel, vacuum forces, and the intake.

But the best way to look at it is, on an inline 4 you have a bank of 4 carbs usually. You could easily feed 2 cylinders with a single carb.

The reason they scrapped that idea many many years ago is you can achieve better performance, better running and greater efficiency by using one small carb for each cylinder to produce even, and precise fuel delivery.

Same applies to a stonking big single cylinder with 2 very big valves. They just have a problem that is more downstream so have to have a carb for even fuel distribution to both valves.

[Harri]

Thanks guys, very helpful. I will get around to carb balancing a little further down the line as all seems okay at the moment.

Barcud