If I bought a 400ex carb for my 300ex will it make a differance? Wut would i jet the carb at?

 

It is supposed to flow a lot more than a 300ex carb, on a modified motor,it would help with top end, I tried it on mine, but the boot from the air box to the carb won't fit over the 400ex carb inlet !! even a 350x boot tube will not fit on it ! Since I wanted it running, I just rejetted the 300ex carb, put the 350x intake on it and put it all back together. Maybe this winter when I have more time, I'll play around and see if I can find an intake that will fit, maybe a 400ex tube? as long as it is about the same length it might work.

 

One thing I'd like to try someday is put a big ski-doo engine inside my fourwheeler. Let's say an 800 Triple. I think it'll go pretty fast.

 

Did you heat the rubber on the 350X tube? I use them on a 44mm intake Lectron - just take out your propane torch and warm the rubber a bit - it will stretch and cool to the new dimensions.

 

I never thought of that,MDE3, I will give that a try. The 400 ex carb seems to be a carbon copy of the 300ex one, just a little bigger, everything else should bolt right up. A heat gun would probably work,too, fire and I don't alway have good luck !!!

 

I suspect you will have to step down a size or two on the jets - given the difference in displacement . Personally I have always used Lectrons on my race quads, which already had the needle I needed in them, and they are adjustable from that point on(the tapered primary needle screws in and out of the slide to change the mixture setting). You might look at one of those. If you talk to the manufacturer on the carb they may be able to give you the best jet kit to start with for that set up. There are so many variations tried out there between pipes, porting, piston, exhaust etc. that you really need someone like the service coordinator at the carb factory to help you, unless you know and engine builder who has modded a lot of 300's (Curtis Sparks maybe). TC Racing has done a lot of them too but he almost always uses Lectrons to go with his engine mods.