Why do Raptors have 2 carbs?

[02silverpile]

OK, I tried to search for this, but no luck. Why do raptors have dual carbs? Is it because they could not suply enough A/F with a single carb in order to be efficient witht the 686? If you have two carbs how do you tune each one to deliever a 13.1 A/F mixture? Are they supposed to be synced? I ahve heard they arent jetted the same, how does that work?

[Tech23]

The left carb is the primary carb and supplys the mixture up to about 1/2 throttle, where the right (secondary) carb starts to open and supply its mixture WITH the primary carb. This allows 2 smaller venturi carbs to combine to = 1 large carb when wide open. A smaller venturi = higher velocity/vacuum through the carb, meaning better fuel atomization and throttle response and, as opposed to a single larger carb with less venturi effect (velocity/vacuum) which will cause poor fuel atomization/ throttle response. No they are not syncronized. They require different jetting because they have different resposibilities in respect to throttle opening AND have some overlap in operation. Essentially you have a 2 barrel carburetor. You should be able to feel it when the secondary carb. starts to deliver its mixture. Hope this helps Tech23.

[cjkranz]

very well stated!!;)

[250r4life]

Originally posted by Tech23
The left carb is the primary carb and supplys the mixture up to about 1/2 throttle, where the right (secondary) carb starts to open and supply its mixture WITH the primary carb. This allows 2 smaller venturi carbs to combine to = 1 large carb when wide open. A smaller venturi = higher velocity through the carb, meaning better throttle response and atomization, as opposed to a single larger carb with less venturi effect (velocity/vacuum) which will cause poor throttle response. They require different jetting because they have different resposibilities in respect to throttle opening AND have some overlap in operation. Hope this helps Tech23

where abouts in AZ are ya?

[Tech23]

Originally posted by 250r4life
where abouts in AZ are ya? I was in Higley, near Gilbert, then I moved to Marana, Northwest of Tucson. I am now temporarily in Baltimore, Maryland. No use in updating my profile until, I find where it is I want to live.