I have a 1996 honda 300ex.The problem i am having is it wont fire and when it does it it doesnt last to long.I put a new plug in and check to make sure i had spark which i did.gasonline is good.The way i have to get it started is to choke it and hold the trottle for a few second then let off then it might start.I just had the carb jetted two years ago.I just cant figure out why it wont stay running after i get it started even when i have the choke on and hitting the trottle to.PLus i live in ohio and its cold but last year it started up when it was -5 out.I even had the battery charger to start it preaty much it.I did all the easy fixes first.Now i need you guys to help me on this problem.

 

Sounds like the carb. needs cleaning

 

i'm going to have to cosign the above post on this..you might want to clean the tank and fuel lines at the same time. otherwise it might be a useless effort, i once had fuel free flowing out my float vent hose. once cleaned no more fuel flow out of the vent..but it didn't start...so i cleaned it 3 more times and thought whatever is going on here is obviously over my head. so i took it to a shop. they cleaned the fuel tank. 45.00 dollars wasted. and it certainly seems to be a case with you're 300ex to. well good luck