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2003 Kawasaki Ninja 250 Frustrations!

I posted a thread a couple weeks ago regarding a Ninja 250 I bought for commuting to and from work. Yes it’s a “chick bike” but it’s a lot of fun to ride. The bike had 226 miles on it and obviously it had been sitting most of its life. The previous owner stated that the bike would only run with the choke on; a potential carborator issue? The bike now has 675 miles and I’ve been putting GumOut Carb cleaner in the tank with every fill-up. After fiddling around with the idle the bike runs MUCH better, and after a couple miles of riding the bike idles really nice.

So here’s my frustration. On warmer days like today, once the bike gets HOT in stop and go traffic, the bike idles high around 4,000 rpm. I can get the rpm to drop down if I adjust the idle screw but then it idles really low and chugs during a cold start-up. On a normal day while the engine temperature stays cool it will typically idle around 1,600 rpm and it runs great. I’m getting tired of the constant idle adjustments.

What is wrong with my Ninja? Is this normal? I’ve owner Yamaha, Suzuki, and I’ve never had this issue. Maybe I should try SeaFoam?

I would appreciate your thoughts.

What you are describing is typical of how a bike acts when it is running lean. You either have jets clogged or an air intake leak. Since you indicate the bike's running has improved with use, you are on the right track with the fuel additives. Try the sea foam or Yamaha's Ring Free. Also, check your air filter to make sure it is in place and seated properly, it will run lean if it is drawing non filtered air.