Re-Jetting carb? - Kawasaki Ninja 250R Forum
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post #1 of 4 (permalink) Old 07-26-2011, 04:28 PM Thread Starter
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Join Date: Jul 2011
Location: georgia
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Re-Jetting carb?

hey guyes just curious do you need to rejet the ninja's carb for a slip on exhaust?
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post #2 of 4 (permalink) Old 10-01-2011, 06:34 PM
Join Date: Apr 2011
Location: Orlando
Posts: 34
yea, i can't seem to get a straight answer from anyone about this topic.. I want to get the entire full system but not sure what can happen if i do and don't re jet the carbs….

2009 Cobalt Blue Ninja 250R ~1k miles
PLM CF Full system exhaust, K&N direct pod filter, re-jetted carbs & full dyno tune. 32 whp & 15 ft lbs
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post #3 of 4 (permalink) Old 10-02-2011, 12:24 AM
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Join Date: Aug 2011
Location: Living in Thailand, but Home is Linden, NC
Posts: 26
I have a 2009 - 250R. I didn't want to have to wear ear plugs on my daily to work bike, so I installed an Area P, quiet core, full system. Area P will tell you, you don't have to re-jet with this system, but I did it anyway. However, I believe if you get a one of the short and louder mufflers with less back pressure, you should re-jet.

It would seem to me if you are adding a slip-on or full system, you are looking for better sound and performance. I'm guessing people ask about re-jetting because pulling the carbs off is a lot of work. You even have to loosen the air box to pull the carbs. (It only takes 20 minutes to swap a muffler, a lot longer to re-jet). But if you are going to start modifying the bike, don't stop with just a slip-on. Spend the money and buy the Ninja Service Manual to help you tear your bike apart.

*****Hey, call up each muffler manufacture and ask them if you need to re-jet with their muffler slip-on and/or full system.******

The factory jetting on the Ninja has a 98 main jet. If you buy a dyno-jet kit for $80ish, you replace the needles and install their 98 or 100 main jets. I'm guessing the dyno-jet needles have a different taper than stock and even the 98 main jets are not the same diameter. So it will be richer.

I've been buying extra main jets from Dynojet for $2 each. (mailing charge extra) Call them and ask if they will sell you their needles and C-clips for your bike. Might be way cheaper than buying the whole kit if they will. Have Fun.

Area P full system, quiet core
DynoJet kit - Needles w/c clips on third groove
Not in kit, #106 DynoJet Main Jets and #40 pilot jets
Removed air box and install K&N 0990 open air filter

Last edited by Allants; 10-02-2011 at 12:29 AM. Reason: correction
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post #4 of 4 (permalink) Old 04-08-2015, 11:12 AM
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Thanks for sharing .......nice view.
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carb, rejetting

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