EX250 Carb Problem

[stickboy]

I have a 97 Ninja EX250, and I am having a problem with one of my carbs. The bike is hard to start. If I choke it, it pops a little bit but never catches. If I take choke off, it pops a little more, but still doesn't catch. I have to hold the throttle about a third of the way open and crank for about 15-20 seconds to get it running. While cranking there is a gassy smell, which makes me think the bike is getting too much gas.

When the bike does fire up, you can tell that one of the cylinders isn't firing right away. I have to rev the bike to about 5k to get the second cylinder to pop to life, and when it does, it smells gassy and is rather loud. It seems to me like one carb is running extremely rich. I took the carbs apart a couple of weeks ago and cleaned them out and adjusted the floats. I checked the slide diaphrams and they looked fine. After putting things back together the bike ran fine. I went for a somewhat long ride this weekend and when I stopped near the end of the ride, the bike started having these problems.

At this point, I either suspect that one of the float needles is badly leaking or there is a problem with the vacuum slide. I did find that the clamps holding the rubber intake manifold on the left carb had come loose. I tightened them and this did not make a difference. I checked the vacuum hoses and all look fine. I have not yet checked for gas in the oil, but I am not sure if I would find much in there as I ride the bike multiple times per day.

Any thoughts or directions to look would be greatly appreciated.

[StarGate]

Have you put new plugs in since this started?

[stickboy]

I have not done the plugs yet. It is on my to-do list for this weekend.

The reason I am suspecting a float problem is because when I got the bike this spring, it had been sitting for quite some time (1-2 years). When I took the side plastic timing cover off, gas/oil poured out of the crankcase. That prompted me to look into the carbs. I cleaned the needles and seats but did not replace the needles. That may be my next step after replacing the plugs.

[stickboy]

So I am convinced it it is a float problem. I ran the bike for a bit last night with the petcock turned off so the carbs would drain (forgot I had turned the gas off and went for a ride). I tapped on the float bowls with the end of a screwdriver and then turned the fuel back on. Now it runs normally again. I did not see any problems with the floats when I took the carbs apart a couple weeks ago. Guess I will have to do it again and check things more closely. I will probably just replace the needle valves to be sure.

[StarGate]

If they are all metal needles you can polish/clean them and the seat and get them to work again most times. If it's the rubber tip needles then you probably need new ones. If you get something other than the ones from a dealer be sure and get a good quality brand like S&K. Cheap brand will get you right back where you are.

[live2betuf]

is the bike flooding out at all... i recently had a horrible flooding problem on my ex250 carb this weekend. i went to a local shop and he tought me a trick to clean the needle seat to avoid buying new ones(which i didnt need). take a drill bit that fits in the float needle hole. and just using your hands DO NOT USE A DRILL!!! turn the drill bit backwards to polish the seat. it worked wonders

[Ericthejet]

So I am convinced it it is a float problem. I ran the bike for a bit last night with the petcock turned off so the carbs would drain (forgot I had turned the gas off and went for a ride). I tapped on the float bowls with the end of a screwdriver and then turned the fuel back on. Now it runs normally again. I did not see any problems with the floats when I took the carbs apart a couple weeks ago. Guess I will have to do it again and check things more closely. I will probably just replace the needle valves to be sure.

2nd time is the charm. I was going to suggest plugs but "someone" beat me to it. Re-clean the carbs is what I would suggest. I re-did mine years ago only to suffer the same fate. Re-did them second time and problem was solved.