jetting carb

[toby400ex]

hey guys, well ive been riding my 300ex with the mods listed below in my (thing that has the mods part). Well im not thinking that anything i am doing is very wrong but im not sure if it is running at its full potential. i have a 125 main jet and dont have any idea about the air screw, i bought my bike with the mods and everything so im not all that sure of the mods done to the carb. Right now my plug is a light brown, like a chocaloate milk powder mix kinda, but sometimes it back fires a whole lot when i slow down and sometimes i will jab the throttle but it will do nothing for a sec, i heard about the k&n power kits making better throttle responce so im confused.

[cals400ex]

i honestly don't know the size of the stock main jet in the 300ex. the light brown plug sounds good though. if its backfiring, that a lot of times means the bike is running a bit lean. the pilot jet should not have anything to do with the full throttle performance. the pilot jet and fuel skrew is mainly for starting and under 1/4 throttle. if its hard to start in cold weather then you could take the skrew counterclockwise 1/2 of a turn or so or you could just put in a bigger pilot jet. i personally would not buy the kandn power kit. i think you can just go buy the jets you need and save a lot of money. the kit will give you many jets that you will probally never use.

[MeatHead]

Mine acts like that too, but only until it is warmed up. Once it warms up it just goes. No hesitation, no thinking about it, it just takes off when I give it gas. I am running a 128 main and a 40 pilot. I believe the stock sizes are 122, and 38. The backfiring when you let off the throttle is probably your pilot, air fuel screw, or the needle. Mine did that for a while until I went to a 40 pilot, and turned my screw out one turn. I was going to change the needle height to make it a little richer, but my screws are stripped and I didn't want to drill them out yet. But it is running great now with the larger pilot. I run a similar setup to yours, only I have a WB e-series pro-meg, and no air box lid. I have been running with the 128 since Labor Day and have not fouled a plug yet, and it looks good everytime I check it. Also what octane gas are you running? I never run anything but 93 in mine and it runs great.

[300EXrider02]

well man i got a power kit which comes with a filter outerwear, cleaner and jet kit, it was good and moto-man.com has it for sale for 99$ or 90$ i forgot, anyways, i put a 124 main on mine becuase it tells u to run a 128 if u have no air box and the one below that is 124 and so i just cut holes and put that in casue i didnt was a dirty **** filter, anyway, u can pick betweena ***** load of jets, so i would go with it, it should be a coconut brown or blackish brown, your machine is runnin a little lean so u gotta fix that, but there isnt a air screw, there is a uel/air screw i guess u could call it, that should be seated then turned back 3 turns if your under 3000 or 5000, i turned it a little more cause i live a 500ft, any other questions about it, ill help casue i did the ****in thing like 9 times:mad:

[toby400ex]

will the backfiring do anything bad, and also if i get a bigger jet like a 128 should it make it not so lean and then i dont have to fug with anything else, cuz i got a harescramble race this sunday so it needs to start quick and keep going.

[toby400ex]

Oh yeah, i think it is either 92 0r 93 octane that i use and i have never fouled a plug in the six or 7 months that ive had it. But i guess that could also mean im running lean also.:confused: