Today i put a 300ex carb. on my '97 300 4x4 and i'm having a few problems i hope i can get some help with. and i did the swap because i don't like having a vaccuum slide and i wanted to have an excelerator pump. and i should also mention i have a full supertrapp exhaust on it, and a power up kit w/ a K&N First my stock cable wouldn't work, the threads on the end of it were to small. so i took a cable off a 250sx and the cable was to short to reach the thumb throttle but i put it on anyway (had to pull on the cable by hand to drive it.) then when i went to put the tank back on, it hit the metal elbow in the cable. so i just let it hit so i could at least test drive it. Then the guy i bought the carb from removed the choke for "better air flow" so i had to pump it like crazy to get it to start. and it runs great and the carb has been jetted. it took off pretty close to normal (maybe a very slight gain) so i went up this hill i can useally take in 3rd and i didn't make it as good as i useally do (started to bog at the top) so i tried it again without the air box lid and no change. so now i'm thinking i'll put all the jets out of my orginal carb in the 300ex carb and see how that is. But basiclly my question is, has anyone done this exact swap before? and what throttle cable did you use? and did it have any power issues? (not enough) and thanks for any help.

 

It seems to me your going thru a lot of trouble for absolutely no gain. Even though you said why you were doing this, I still have to wonder what you think you will gain by doing this. CV carbs are used on countless machines w/ no trouble whatsoever, so I'm not sure what your beef is against them. Your completely rigging your machine just to make this work, I hope the rest of the machine isn't cobbled together also.

Tell the guy you bought the carb from that the choke is there for a reason and to remove it for "better air flow" is the stupidest thing I have ever heard. Ever heard of an air leak? You have a huge one w/ the choke removed. Replaced the missing parts and it'll run much better. If the machine ran better w/ the airbox lid removed (which you said it didn't) then you could assume your running rich, but because it made no difference its safe to say your running lean and thats why you're losing power going up the hill.

Another thing to consider is the size of the carbs, is the one your trying to install bigger or smaller? This will affect what you need for jetting and where the engine will want to run better. A smaller carb will gain low end power but lose top end. A bigger carb will gain top end but lose bottom end. Check the size of the venturi w/ a dial caliper.

 

i didn't like that the choke was missing either, i am in the search for one now. and the guy sealed the choke where the shaft went with silcone so there is no air leak.
besides the throttle cable, which i should be able to find, it is a direct bolt on, with no mods needed. and i want to do this swap to get better low end throttle response.

 

I can't help with your immediate problem, but I've had an interest in doing this for a long time. 1988trx, I think that there is a lot of gain. The responsiveness in my recon I think is directly related to the fact that the carb is not CV. I want to put a non-CV carb on my rancher.

Blue83, keep us posted on how it works out and if you get the performance you want.