All about the Kawasaki Ninja 250


Muffler Modifications

Many riders get overcome by the temptation to put different (i.e. "better") mufflers on their 250 Ninja. I'll talk about 3rd generation (86-07) bikes here, but much the same applies to the 08 and newer bikes.

There are three reasons usually given for for changing the stock dual muffler system on the 86-07 bikes. They are:

  1. To reduce the weight of the exhaust system (I think the stock headers and pipes weight around 25lbs)
  2. To increase performance by allowing the engine to "breath" better
  3. To sound better (where better = louder)

It's true that almost any aftermarket exhaust system will achieve #1, weight reduction. However on a street bike a small weight reduction really isn't going to make a big difference to performance. So while #1 is true, it's questionable if it makes much difference.

It's also true that better engine breathing (#2) will give you a little more top end power. However to get it you'll need to rejet the carbs and, if you are going to do that and not go crazy taking the carbs off and putting them back multiple times, you'll want to replace the stock filter with pods. If you do all that and you get the jetting right, you might get a 5% power increase. If you are very very lucky and get the right parts and do everything perfectly you might (and I emphasize) might even get 10% extra power at the top end (say around 13,000 rpm). However if you do that and tune for max power at the top end you may lose some power or torque lower down and you may make the bike less driveable at lower rpms. That doesn't always happen but it can if you don't get the carb rejetting right.

If you add a freeflowing aftermarket exhaust and pods and you don't rejet the carb, you may end up with less power than you started with and a bike that won't run right. It will probably run lean throughout the rev range with stumbling, misfires and possible overheating resulting in burned valves..

There's no doubt that you will achieve #3 (it will be louder) - what's "better" depends on the ears of the listener. Louder means somewhere between quite a bit louder and "wake the neighbors and make your ears bleed" louder. If you haven't been riding with earplugs on the freeway, you'll probably want to invest in a pair with the new muffler. In most states the bike will technically be illegally loud, though unless you have the "bleeding ears" muffler(s) you may be lucky and not get a ticket.

So the bottom line for most riders is that replacing the mufflers isn't worth the expense and effort for street riding. However despite that, lots of people do it and some of them don't regret it and don't put the stock mufflers back on - so what are the options?

Kawasaki Ninja 250 Muzzy Exhaust
2 into 1 Muzzy exhaust on 3rd Generation Ninja 250

  • The Muzzy system. This replaces everything. It consists of new "2 into 1" headers and a single muffler on the right side of the bike. Available for both 3rd and 4th generation bikes, the cost is around $500 for the system with an aluminum muffler to $700 with a titanium muffler. A "slip-on" muffler which uses the stock headers is available for the 08 and newer bikes at a cost of $400.
  • The AreaP system. Available for both the 86-07 and 08-current models. Again a "2 into 1" header plus muffler arrangement. Prices from $450 to $525 depending on exactly which muffler you choose.
  • Yoshimura slip-ons. These are new mufflers which replace the stock mufflers but use the stock headers. Installation should be easy as you just remove the stock pipes and "slip on" the new ones. Price will be around $450.
  • Two Brothers make slip-ons for the 86-07 Ninja 250 at a cost of around $400 for a basic pair of new mufflers. For the 08 and newer bikes both slip-ons and a complete system (with headers) is available. Prices range from around $400 for the basic slip-on to over $1000 for the complete system with a titanium muffler.
  • Though no longer available Cobra made slip-ons for the 86-07 bikes. There were two models, the F1 (loud) and the later F1R (very loud). You might find used ones for sale - expect to pay between $100 and $200 for a pair.