WHy is this? also what more will have to be done comapared to single? also when should they be jeted?

 

jetting is more of a prob with more than one carb, but i cant really say why the raptor has two carbs. im sure those more knowlegeble then I in this area can tell you, but i dont see why the raptor NEEDS 2 carbs. yamaha could have gotten away with 1.

EFI would have been better of course. Yamaha has a similar engine as the raptors in one of their bikes in europe (660XT R) - it is EFI. I think it could be used as the next gen raptor engine oneday.

 

u got a link to view the eurapean bike?

 

translated link

yahoo had to translate the page so i hope it works for you.

 

It should have just had one simple effective carb and thats it. More crap = more worries.

 

I heard somewhere it was for throttle responce...but I dont really know.

 

Probably to give the intake a straighter shot at the valves though I still cant say I think it was a very good idea. Probably just yamaha trying to be different, same as the 5 valve thing.

 

The first carb is your primary..keeps the bike idling and works the first quarter throttle..the second carb is the secondary that with the first carb feeds the fuel for high rmp....1 carb doesn't work as well as two..There are alot of guys who tried the single carb set-up and they are all for sale on different sites.5 valves....thats a premium....all these things add up to a Raptor having lots of potential. Thats why it's a Raptor. They should be jetted after installation of a pipe and filter or anywhere after about a 6000 foot elevation although they still run well at high elevation simply by removing the air box lid(if it's stock)

 

I really hope you don't take this the wrong way, but thats so far from accurate info its not even in the same ball park.

Two carbs should help keep intake velocity up while still giving you large intake volume. Both carbs work at all rpm and throttle positions the same.

The only single carbs off of a Raptor I have ever seen sold are the Edlebrock ones.

 

A smaller carb has better throttle response than a larger carb. Since the raptor needs lots of fuel, they put a dual carb setup for better throttle response.

Whether or not the dual carb setup is best for the five valve head is debateable. While it doesn give better paths, there is a great deal of turbulance to the point of reduced flow to the center intake valve.