2001 Ninja 250R High Revs

[JahCraft]

Hey guys, I have a 2001 Ninja 250R with 5k miles on it. I bought it about two years ago and haven’t really touched it since then. I bought it from a guy who let it sit with gas in it so I finally decided to get around to it and clean the carbs. After I cleaned the carbs I put it back together and it stayed up but revs to 4-5k rpm cold or warm doesnt matter. I have already tried backing out the idle adjustment screw, but didn’t do anything even all the way backed out. I sprayed starter fluid between the engine and the carbs and the rpm’s didn’t rise, but when sprayed behind the carbs where the intake connects to the carbs the rpm’s would
lower back down to a reasonable number. I am guessing it has to be that boot since the boot doesn’t have its sprint style clamp holding it to the carb. Also after it has ran for a while revving at 4-5k and I turn it off it won’t start again.
So to recap:
Engine reviving at 4-5k and the rpm’s are stable and don’t hang. When i rev it they come do right away back to 4-5k
Engine doesn’t start after it’s been running for a while.
Thank you

[thedrewski86]

If that boot isn't sealing on the back of the carbs, remove the air filter and (with your tiny pair of hands if you have a spare set!), see if you can get a hand into the airbox and get a finger or two into the carb throat. Those rubber boots have an inner rubber lip that has to seal into that carb body and this is the only way I have found to consistently seal up that area. If you have an air leak in this area, you will be stuck around 4-5k rpms like you described.

[jkv45]

Originally Posted by JahCraft

Hey guys, I have a 2001 Ninja 250R with 5k miles on it. I bought it about two years ago and haven’t really touched it since then. I bought it from a guy who let it sit with gas in it so I finally decided to get around to it and clean the carbs. After I cleaned the carbs I put it back together and it stayed up but revs to 4-5k rpm cold or warm doesnt matter. I have already tried backing out the idle adjustment screw, but didn’t do anything even all the way backed out. I sprayed starter fluid between the engine and the carbs and the rpm’s didn’t rise, but when sprayed behind the carbs where the intake connects to the carbs the rpm’s would
lower back down to a reasonable number. I am guessing it has to be that boot since the boot doesn’t have its sprint style clamp holding it to the carb. Also after it has ran for a while revving at 4-5k and I turn it off it won’t start again.
So to recap:
Engine reviving at 4-5k and the rpm’s are stable and don’t hang. When i rev it they come do right away back to 4-5k
Engine doesn’t start after it’s been running for a while.
Thank you

If you are confident it's not a vacuum leak, I would say something is hanging-up in one of the carbs.

There may be something that was not reassembled correctly.

See if you can determine if one of the slides is not fully seated.

Look at the throttle cable routing and check that the throttle pulley on the carb is in the idle position. Make sure the throttle snaps closed properly.

Once you solve the issue, I would sync the carbs and precisely adjust the idle mixture screws and idle speed.

https://faq.ninja250.org/wiki/Intake