Question about Carb Swapping

[burndout]

In theory if your bike came with a 35mm carb could you take ANY 35mm carb, buy the right boot and cable end, jet and use it?

The reason I ask is due to working out some kinks on a current build. The motor is an EX500 (kawa ninja) and comes with 34mm CVK carbs but due to extensive work to the exhaust (fully hand built) and no air box (no room) I have been told that it will not run good even with tunning if I "could" get it right due to the vaccuum activated slides. I thought about just running a slide style and found the Keihin CR Round slide carbs but they are super expensive. Could I just run 2 PWK 35's instead? Pros and cons of this setup? Thanks!

 

[Braaaptor]

You have a high-performance cam in that engine, don't you? Hence the lack of usable manifold vacuum. Setting up something like this is beyond my experience (and I don't like to comment unless I've seen or experienced what you're talking about firsthand), but I will say that you're probably right about the CV carbs not working properly. I would keep the four carb setup on this engine, but I suppose a 2-into-4 system would work OK if it is tuned correctly. I don't see why 2, 35 PWK's wouldn't work, but you will lose some top-end power running two cylinders off of one carb. A lot of that depends on the length of the intake runners. The longer the runner, the better (generally) it will work. If space is a concern for fitting the carbs, I'd think twice before doing it. Using a short intake runner on a 2-into-1 setup can cause unequal distribution of the intake charge between the adjacent cylinders, and a disruption in velocity, resulting in loss of top-end power and throttle response. I'm no pro tuner, but there's my .02.

 

[burndout]

I wouldnt be moving from 4 to 2 carbs, the EX comes with 2 in stock from. The question is that can you move from CV carbs to Pumper style carbs without loosing power or any performance? It seems like the CV carbs are better than Pumper style, why are more people not running CV carbs?