Is this the problem?

[01_300ex]

My 300ex will not start. It ran fine one day and then the next day it would not start. I would just sit there holding the starter and it wouldnt turn over except for a few times. And when it would turn over it would only run for a second or two. I changed my plug and checked over all of the wiring. Also, my friend towed me behind his truck to try and roll start it and it would still not start. Another thing is that when i turned my air screw out alittle bit, gas would start coming out of the vent lines on the carb.

[timewass]

Sounds to me lie your float is stuck open and it's flodded.

[01_300ex]

well i went back out there today and took off the bottom of the carb, and every thing looks like it is on right, but gas still comes out of the vent lines when i turn the airscrew out. What else could I look at.

[01_300ex]

well now gas does not come out of the vent lines when i turn the air screw, but it still will not start. Its getting spark and everything. Name some other things that could make it not start. And remember, it ran fine the day before the first time that it would not start.

[crashinmatt]

sounds to mean that something is plugged in the carb. i would take it out and clean the whole thing inside and out as good as u can. also, just make sure ur gettin plenty of fuel flowin in the carb, it sounds like u r, cuz ur sayin it comes out the vent tubes.

[01_300ex]

well i cleaned out my carb and everything, and it still will not start. Could somebody tell me something else that could be making it not start.

[TRX_Thumper]

LOL if it makes gas come out of the vents thats not your air screw...thats the screw that emptys the bowl...tighten that screw and see if it doesnt start

How many hours have you put on it without a rebuild? If it is a lot, then your motor might have been locked up for a problem with the carb. If not i would check the crank and valves, one or the other could be locked or plugged too.

[01_300ex]

it was rebuilt last march, but i havent put very many hours because i broke my shock and stuff. And also, i found out that it wasnt the airscrew,lol

[01_300ex]

bump

[trueblue450]

open the fuel valve from the tank..
take off the hose to the carb and make sure its draining fast from the valve.

If it is check your spark, then see if it is pure black or grey or what.

Make sure you arent in reverse or its not engaged.

Its either air, fuel, or spark

check em all over again.

[01_300ex]

its getting spark, so its not that. I am getting gas from the gas tank to the carb

[northeast400]

You may have flodded it and washed the cylinder down, I did that once, remove the plug and put a cap full of oil in the cylinder, put the plug back in, wait a second and try to start it, the problem is if the cylinder is washed down it can't build compression, the oil seals the rings just enough to crank it over.

[01_300ex]

im going to try that and see if it works.

[nosinjcted]

I've never heard of that oil trick but it'll work or it won't if thats your problem.

After reading all the posts on your problem I don't think its with your fuel. How clean is your air filter. If it's not getting enough air then it won't start either. I've seen bikes that wouldn't start and we'd chase everything wires, change plugs, clean the carb and then clean the filter or try it without the filter (i can't recommend doing that) and it would start right up. Maybe thats your problem.

[01_300ex]

It could be the air filter, but i dont think it is that dirty. I will still try it though.