Carb Problems really need help

[Nate's96 300ex]

Alright I have a 96 300ex with a fmf performax full exhuast oil cooler and a 400ex carb and alot of other stuff but i dont need to include that right now. Well when i first got the 400ex carb i jetted it and everything and it was running awesome. I had the carb on for about 6 months with no problems, Untill just last weekend. I guesse it started on night when my quad sat out for a while in the cold which is the first becuase its usually either running or sitting in a heated garage. Well when i came out to start it it wouldnt start so after awhile of trying to get it started i pushed it back to the garage and took the plug out and cleaned it and put it in and it started up then i left and came bake the next weekend and it wouldnt start then i finally got i started and it took a while to warm up and it was spitting and sputering getting all the flooded gas out of its system well after it was running good i took it down the road. It was running fine until i tried to pin it wide open i pushed the throttle all the way and it just bogs down it also does in every gear if i try to push the throttle fully in it seems like its over heating cuz it feels warmer then usuall ive change the oil many times but i havent changed the oil filter in a very long time i think i have 1 since i got it. CAN anyone help me with this prob please I really need help

[Nate's96 300ex]

Come on not anyone has a clue?

[papaw]

nate is it clean?are the vent hoses in the right place?did your main jet fall in the bowl?it sounds like one of those stupid easy obvious fixes.double check the vent hoses i've seen it happen and it makes a big difference.

[Nate's96 300ex]

I just got down tearing it all apart and everything seems fine everything is in the right place jets all in place carbs clean i dont know what the prob is i think it might be the throttle cable because the day it first started doing it it was cold then a turned a heater on and pressed the throttle and it was very easy to push but before i turned the heather on it it was a little hard since it was cold but i dont know. IF ANYONE has a similar setup as me please tell me what u are running for jetting i would greatly appredciate it

[Nate's96 300ex]

Please someone reply with some jetting recomendations

Nate,

I think if it had run good before with the jets that are in now then it sounds like its not a jetting problem. I am assuming that you ran it since the temp starting dropping as the colder denser air could make a difference as it would allow oxygen into the motor, but I suspect this is not the case.

I would first get a new spark plug just to take one potential problem away. ( a cleaned one is not as good as new).

You could also check your throttle adjustment.

I would think of what had been done or changed since you left it out in the cold.

Hope that helps.

[Nate's96 300ex]

alright thanks

[4punksdad]

what color was your old plug when you removed it? your jetting might be off, and you are fouling the plug?
my 400ex is running rich with a 165 main jet. I think I am going back to the stock 148 & see if the plug clears up.

the problem you describe sounds like a vacuum leak. my 400 carb popped off the intake boot one time and caused the same problem.

the members above have given you good suggestions.......keep trying.

[Nate's96 300ex]

Yea 4 punks they have given reall good info and yesterday i took everything off and cleaned it and put it back on, Next thing will be gettin a new plug the plug whe i would pull it would be a litte dark it might be because of the weather and temperature change cuz it was tan in the summer and fall. I am running 48 main and 42 piolite the carb gives my 300 a good power gain, but i know it would be alot better if it was fine tuned with perfect jettin thats why i am askingall the owners of the 300ex with a 400ex carb ad ful exhuast with k&n filter and no airbo lid or a similar setup help me out wth what they are running.

[SGA]

Sounds like the main jet may have a piece of trash in it. Pull it & look through it. check the air filter also, needs cleaning? that would make it rich tho. sounds lean on the top end to me. I think the jet size is o/k since it ran o/k before.