How to tell if bike is running lean? - Kawasaki Ninja 250R Forum
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post #1 of 4 (permalink) Old 11-01-2012, 04:35 PM Thread Starter
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How to tell if bike is running lean?

So I just bought a 09 and didnt get much information on the service and upgrades on the bike. I have already changed the front sprocket to a 15 tooth and replaced the air filter with a K&N filter. Have heard alot about getting the carbs rejetted or atleast shimming the needles which i have read alot about and think that i can do it myself.

So my question is how do you figure out if the bike is running lean is there any signs that you can look for to tell you? The bike came with a slip on muffler if that helps. Just looking for someone with more knowledge to help me out and point me in the right direction.
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post #2 of 4 (permalink) Old 11-01-2012, 05:46 PM
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The first thing is to see how it feels when you give it gas and rev the engine past 7 or 8 thousand RPM . How does it pull on the highway? And how does it run when it is cold. This will also indicate a lean condition. BUT totally different solution to those running conditions.

Also the next thing is to remove the spark plugs and look at them. If they are white like new. Then you might be a little lean.
How does it run over all? How is the milage?

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Last edited by Racer X; 11-01-2012 at 05:47 PM.
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post #3 of 4 (permalink) Old 11-01-2012, 07:32 PM
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I got a 2012 ninja 250 and have k&n filter in stock airbox with snorkel removed, and a slip on muffler. I had to rejet my carbs to compensate for the extra airflow. I could feel the difference. More than likely, you are running lean...

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post #4 of 4 (permalink) Old 11-02-2012, 10:22 AM Thread Starter
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Well the bike runs fine once its warm if its to cold i dont get a good responce outta the trottle but once warmed up does good the new sprocket helps alot with the pull on the highway. The bike has 4,300 miles on it. Cant really tell a differnce in it thats why i asked about different signs to look for. Im gonna look at the plugs to see but dont know if thats gonna help bc the plugs were in it when i bought it so dont know what the previous owner has done. Overall runs good just dont wanna mess anything up as i just bought it and upgraded a few things.
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