The Kawasaki Ninja 400 and Z400 are awesome little bikes! Kawasaki made some advancements to the little bike scene offering a 400cc package that was just as lightweight (or lighter) and nimble as other 250cc and 300cc bikes. But like with anything that’s a brand new design, there are a few quirks that should be addressed to really top off the great work Kawasaki did with the 400.
1. Clutch and Shifting
The Ninja 400 engine has some shortfalls in the design and manufacturing of the clutch and shifting mechanisms that are pretty widespread. Please read our full detailed article here for all the information and solutions:
2. Front Brakes
The front brakes on the Ninja 400 and Z400 are pretty good for a beginner street bike. A new set of front pads makes a world of difference and go ride and have fun. But if you are planning on taking your bike to the race track, you definitely want to read this article on the front brakes before you warp your front rotor:
3. Cylinder Coolant Seal
This one is a major bummer. I’m pretty disappointed at Kawasaki for this little gem. This is just piss poor engineering. The rubber seal around the coolant passage that allows coolant to travel from the cylinder head down through the cylinder to the engine case has a tendency to deform and fold over and cause a leak. It’s easy to see why too, it’s a tall and skinny seal that’s just floating in an open cavity. A rubber seal that is tall and skinny is always going to try to fold over. It has to be contained if it’s taller than it is wide, that’s just basic engineering 101.
Unfortunately to get to this seal to replace it, you have to remove the cylinder head (and replace the head gasket) and either remove or at least loosen the cylinder (and you should replace the base gasket). The engine doesn’t have to come out of the frame, but it’s still a lot of work. We have designed our own replacement seal to solve this issue once and for all. You definitely don’t want to repeat this procedure, so do yourself a favor and replace this seal when it’s convenient before it fails on you when it’s really inconvenient, like Friday practice before a MotoAmerica race weekend… For street riders and track day guys, I’ll leave it up to you whether this is something you want to make sure doesn’t happen, or just wait and see if it happens to you and then get it fixed. But for racers who don’t want to waste a whole weekend or go through an unplanned engine tear-down, I highly recommend replacing this preventatively:
4. Track Bodywork
This is not really a critical issue unless you are building a track only or race bike. The Ninja 400 ergonomics leave a lot to be desired for track use and racing. The standard body shape has a very high and wide front/side fairing which doesn’t allow much clipon adjustment without major bodywork modifications, even with aftermarket clipons and steering stops. The gauge cluster is mounted to a piece of the bodywork, so it’s a pain in the butt to remove with some bodywork and often times an aftermarket fairing stay is used to re-mount the gauges. The coolant reservoir and voltage regulator are mounted to the upper fairing stay, so these are commonly moved inside the frame with aftermarket options. The tail section also has a very steep hump that forces the rider forward and close to the handlebars. This position is downright awkward for track use and racing. These ergonomics are worse on the Ninja 400 than other similar bikes, so we decided to build an entirely new bodywork kit for the Ninja 400 based on a Moto2 bike to take full advantage of the awesome little engine and chassis package Kawasaki gave us.
So before you invest in race bodywork, be sure to take a look at our Norton GP Spec race bodywork for the Ninja 400. You will not regret it. It does requires the purchase of a few additional parts to properly mount up the first time, but it’s much easier to go on and off the bike than standard bodywork, and the reality is that most people are replacing these parts anyway for other race bodywork, so it’s not really much different and it’s a far better track package with the GP bodywork. Plus the engine cools better. Win – Win.