Just curious.

 

Maybe because of the 5 valve design or maybe just to make it more complicated.[img]i/expressions/face-icon-small-happy.gif[/img]

 

one is a primary carb other is secondary. i know one is to do with the valves and other for cylnder.

 

I think the primary and the secondary carbs kinda act like a psudo DOHC effect. I know the Mojaves used to have a DOHC and the second kicked in at a certain RPM to give a sort of "4-stroke powerband". I'm not sure if that's how today's DOHC's (YZ450F, YZ250F, YZF450F, etc.) work. But I always thought that the secondary carb would kick in at a certain RPM to give more pwoer. Just MHO, of course, I really never know what I'm talking about.

 

You could be right jigjew. Ya never know.

 

the two smaller carbs are for increased off the line throttle response, if you were to replace with a single carb equal to both the smaller carbs, there wuld be a lot of hessitation off the line.

 

good point, never thought of it that way.

 

If you want the real reason, it is because YAMAHA was TOO lazy to change up the Street version of the engine. Thats why the 01' trannys had so many problems,and the Starter is to weak. ATVer's are hard on thier machines and if you dont biuld it to thier specs then you WILL have problems. They should have reworked the Rappys head to work with a single carb(much easier to tune) and they should have BEEFed up the trannys(which the did later) and starter gears.


Bombardier also used a "street" version engine of of the BMWf650 street bike, BUT they reworked them to be ATV TUFF!! They changed Gearing, and went to a single carb! the only thing they missed was the shifting forks, and THATS what you have to watch out for if your a Bomb owner.

All rappy owners will agree(even if they dont like the DS) that the DS (as a whole) is MUCH easier to work on then a Raptor.







Bigger.

 

The DS is much easier to work on than the Raptor..I think the raptor has 2 carbs, incase one falls off. [img]i/expressions/face-icon-small-wink.gif[/img]

 

the problem is when both carbs fall (or is it POP) off...

Wayne, I guess I never heard or kept up on it-- but how did the whole engine thing work out? Did you ever get some of your money back from Knutz once you got the engine???