Please help me - Kawasaki Ninja 250R Forum
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post #1 of 3 (permalink) Old 06-13-2019, 03:26 PM Thread Starter
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Join Date: Jun 2019
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Please help me

Ok any an all help would be appreciated cause im out of ideas. Have a 2012 ninja 250 i put aftermarket slip on exhaust, took out airbox an replaced with individual air pods, went with a bigger jets #42's raised the needles one shim, an put in the best spark plugs i could find. Now for the dilemma the bike throttles through all gears great an climbs speed good but tops out at 60mph an wont go past 8rpm it will hold 60 for few minutes then cuts out an starts dropping speed unless i let off throttle an climb back to 60. Please help me
Mandew29 is offline  
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post #2 of 3 (permalink) Old 06-20-2019, 02:38 AM
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Location: auburn, al, usa
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Sounds like you have to much fuel. Pull spark plugs and look for the rich condition. You should not have to change the main jet with a slip on. I just added shims and mine runs great. The correct way is to work on each fuel circuit:main jet then needles then idle/pilot circuit. If you have not already you may need to adjust via the adjustments screws, if you have not you should pull the plugs/metal caps out of the carbs to adjust.

Or you can have someone hook it up to the exhaust machine and get it dead on. There are some really great articles on here that will help. If done manually this is a pain because you have to be able to do several things: adjust, pull spark plugs, ride then repeat.
samson12693 is offline  
post #3 of 3 (permalink) Old 06-20-2019, 03:13 AM
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Join Date: Jun 2019
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Intake mods doesn't yield any benefits. Airbox and filter is larger than the ones on my CBR600RR with 5x more power. So there's absolutely zero restriction on intake side and removing it won't have any benefits.

Go back to all factory jetting. Bike run too rich from factory.

I have full Tyga race exhaust with maggot muffler (way loud!) on my race bike. Got dyno-tuned by sponsor Spears Racing and it still ran rich with 20% more airflow and 20% more power. They ended up downsizing main-jets to 96 from 98. Absolutely screams to redline and I picked up 5mph more top-speed..
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