Join Date: Aug 2011
Location: Living in Thailand, but Home is Linden, NC
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; 10-01-2011 at 11:29 PM.