Bike starts fine when I first start it up. The problem comes after I have ridden for awhile and stop for fuel or a break. After bike sits for 5-10 minutes, bike does not want to start. It will sometimes start if I pull choke out, and push start button as I give it some throttle. I know this shouldn't be happening if bike is already warmed up. It also sounds like it is sucking in air through the carburetor. I have checked the intake hoses from fuel petcock to carb and no leaks. Any ideas of what could be causing this? I was thinking carburetor, but some people have said its an ignition problem.

 

First thing I would look at is fouled plugs. If they are wet or sooty, you are likely running too rich. When the bike is hot, it should start right up with a little throttle and no choke. Too much choke will foul the plugs pretty quick. A clean or new set of plugs would be my first move.

 

Have you made any recent changes to the bike that preceeded the problem?

 

I had the carb cleaned about 2 months ago, but the problem just started. No other changes. I bought the bike used so not sure if the previous owner changed the plugs or not. I will get some new spark plugs tomorrow and see what happens. Thanks

 

Sometimes when things get put back together, it doesn't go just right. The sucking air problem could be a hose or gasket... Perhaps the carb cleaning person also tweaked the mixture too much as well.

 

Check for air leaks around the intake manifold where they go into the cylinder heads. When you pull the choke out you are activating in layman terms a mini carb i.e more gas. When the motor is hot everything expands including the atomized fuel. If the fuel molecules are too far apart they will not support adequate combustion. So when you pull the choke you supply more fuel & less air. When you examine the spark plugs they should be a rust or tan color indicating balanced combustion. If the are a sooty black you are running rich, if they are white you are running too lean.

 

Changed spark plugs today. The old ones were very black, so I guess the bike is running rich. After changing plugs, the problem is still there. Talked to a buddy that has an '02 NT, and he said he sounds like it is the ignition module. Guess I will be getting that looked at too.

 

Then the solution is to get the carb mixture leaned out so the bike is not running rich. Doing something with the ignition module will not solve your problem. You said work was done on the carb...that's a clue to the source of your problem, along with the evidence of the fouled plugs.

 

If the problem is the carb running too rich, why does it not want to start after it has been running for awhile?

 

Likely because the carb problem is not sorted out. A hot bike with an overly rich mixture, plus a hissing noise at the carb, unknown mods to the intake(?) by the previous owner, all are clues to the problem. There could be other things going on, so you need to get it looked at by a motorcycle mechanic. Just trying to point you in the right direction...it's nearly impossible to diagnose a problem without hands on the bike. Good luck with getting back on the road.