so i just disassebled and cleaned out my 87 honda 250x's carb. i noticed that the main jet is a 125. my girlfriend has a 2007 honda 300ex which only has a 122 main jet. i was experiencing some idling (which isnt a mj problem i know) and starting problems. also the needles are different in the 250x and 300ex stock needles. my 250x has 5 grooves in it and the clip is in the middle groove. also the last 3/8" on the pointed end of the needle is smaller. i was just going to drop her needle and MJ in my carb to see if it would help. i also adjusted my slow jet to 2 1/4 turns. so im hoping this thing will start in less than 30 kicks with the throttle half open. anyone help me on which jets i should be using?

 

You should put her whole carb on your bike and see if it helps . As far as the different jets that shouldnt make too big of a difference . Your bike has the stock jets and the clip is where it should be . Did you check the slow jet to make sure it wasnt clogged ? Does the idle go up and down when you turn the air screw ? If not then its clogged . good luck

 

well... right after i took it all apart, and cleaned it i realized that i forgot to pull the gasket out for the top plate for the carb. GUESS WHAT!!!?? it swelled up from the carb cleaner and i cannot get it to shrink back. any suggestions? i could use liquid gasket temporarily. so i have no idea if my cleaning has amounted to anything. if i put her carb on and it doesnt run right, then what?

 

Your ideling and starting problem has nothing to do with the main jet. This is a pilot jet problem only. Did you clean the pilot jet?

 

hey doc, thanks for your input. i do know that the idling problem is not caused by the main jet. i did take the pilot jet out. i just had some diffuculties on taking an important gasket out and it swelled up from the carb cleaner. i really dont want to use liquid gasket on it either. but if i have to use liquid gasket, i suppose i will... that 250x is every bit of fun if not more fun to ride on the trails(atleast around here lots of low speed technical areas) thank you for everyones input

 

Hope you get it going soon Leroy400EX!!! Let us know when you do!!

 

so luckily i left the gasket outside in the cold over night and it shrunk enough to fit back into the carb... got it all back together and it still starts hard. once its warmed up it starts fine with a little blip of the throttle. it will not start with the full or half on. it has to be off with about 1/4 throttle. now! if i roll on the throttle easy it will go from idle to red line. if i try to stab the throttle from 1/4 throttle to full throttle it bogs and doesnt clear up until 3/4 throttle. i know the carb is cleaned and im leaning towards buying the rebuild kit for the carb. i stuck the nozzle in the main and the pilot jet and watched the carb cleaner spray out of the pilot jet holes, and through the main jet. i also tried a trick that i used to fix my banshee and clipped 1/2" off my coil wire. i didnt replace the spark plug cap. it doesnt look like its in too bad of shape. hopefully someone can shed some light on the subject.

 

I copied this from another site . If your bike bogs from 1/4 to 3/4 throttle it sounds like your needle jet . Swap it out of your other quad or check to see if its not binding up somehow ? check to see if its the same length as your other one ? Sometimes the plate that secures the jet at the top of the carb will come loose ?

The Mid-range circuit is responsible for throttle openings from 1/4 throttle - 3/4 throttle.

This circuit is controlled by 2 things: the Jet Needle, and Needle Jet (a.k.a. the Main Jet Holder).

The Jet Needle, or needle as many call it, is attached to the throttle slide, and drops into the Needle Jet. All needles are tapered. Either the Jet Needle is adjustable or it is not. If there are more than 1 grooves for the needle clip to sit in, then it is adjustable. By raising the clip on the needle, you are allowing the needle to sit deeper into the needle jet, which restricts fuel, effectively leaning the mixture. By lowering the clip on the needle, you are raising the needle out of the needle jet, which allows more fuel to pass, effectively en richening the mixture.

When the slide raises, it raises the needle out of the needle jet, allowing fuel to pass by the needle and into the Venturi. This is where needle taper comes into play. Unless you are extremely fine tuning the carb, you don't need to worry about taper. You change which part of the taper is in the needle jet by the position of the clip.

Remember, the Mid-range circuit is only effective from 1/4 throttle - 3/4 throttle. None of the other circuits have a drastic effect on this circuit, so if your problem is in the mid-range circuit, then it can't be the main jet or the pilot jet.


Hope this helps . Try to swap out the carb if you have another one . If your bike runs good then you will know your carb is bad / or needs rebuilt

 

thanks for finding that bit of info for me. i have a stock 300ex needle i can swap mine out with. im really thinking about buying the carb rebuild kit for my 250x. just so i know that everything is NEW. so if i completely disassemble my carb whats the best way to clean the external of the carb? im thinking about a tub full of soapy water and a tooth brush, then spray carb cleaner throught all the nooks and crannies. but that doesnt really sound like a great idea to me... idk. i will try to swap out the needles and let you know. im going to head out side and do that real quick now. one more thing, whats the air/fuel screw supposed to be set at? 2 1/4?

 

so i just got back in from swapping out the needle from my 250x with a stock 300ex needle. it ran the same at first. i rode a wheelie and it seemed to be running perfect for about 5 minutes and then right back into the same bog when snapped WFO. im going to buy the rebuild kit and go from there. atleast then i know what i have. i almost thought my floats were sticking, but if that were true i would be leaking gas all over the place. and its running decent so they arent stuck in the full position not allowing fuel to get into the bowl. i dont think its electrical, definately something carb related... im going to run this tank of fuel through it and then tear it back apart. only because my shut off valve doesnt work... still lets a trickle flow