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Race modifying a Kawasaki Ninja 250

When moving up from Minimotos and MiniGP, A2 category bikes are a popular choice of weapon. How do you race modify a Kawasaki Ninja 250?

Kawasaki Ninja 250 is a popular race bike for young riders.

The A2 category bikes are popular race bikes for young, aspiring riders, and smoothen the transition from MiniGP, let alone Minimoto to Moto3 spec machinery. In this article, we hop along to modify a brand new Kawasaki Ninja 250 to race specification. These bikes are typically used in classes where modifications are limited. This is the story here as well – the allowed modifications are limited to installing race plastic, and swapping the exhaust to an aftermarket slip-on. Required modifications include removing lights and mirrors and securing certain bolts with steel wire. 

After unboxing, the first thing was to strip the bike down.

The first thing after unboxing was weighing the bike. Ready to ride weight sans fuel was 158 kg. The modification started with fairing removal. Also all lights, passenger footpegs and plate holder were removed. The original silencer turned out to be rather heavy and replacing it with a GPR item gave substantial weight savings.

Aftermarket slip-on gave significant weight savings along with noise improvements. 

The rules state that if something isn’t specifically allowed, it’s forbidden. Removing the passenger seat lock wasn’t specifically allowed, but it wouldn’t clear the tail fairing. We decided to remove it, but keep it in case some eager inspector thinks it must be installed. In order to switch the gear pattern to the racier 1st up, the rest down setup, it was necessary to cut a part of the front sprocket cover away in order to make room for the gear linkage.

In order to reverse the gear pattern, the front sprocket cover needed a bit of cutting. 

When installing the fairing, we discovered that they weren’t of the best quality. Thickness varied substantially in different parts of the fairings, for instance the other mounting point of the tail fairing was basically only top coat. Due to tough schedule we had to use the fairing as it was, but undoubtedly some layers of glass fiber would be required in the future.
The next step was fitting new clip-ons. The original, above triple clamp items were binned and replaced with PP Tuning bars, which were fitted under the triple clamp in order to get the rider in a more aggressive position instead on the upright, relaxed ergonomics of the standard bike. The clip-ons were also positioned wider than standard in order to increase the steering leverage.

Suitable clip-ons weren't available, so we needed to use sleeves.

The lower than standard clip-ons didn’t have enough clearance. The problem was solved by removing material from the fairing and the gauge bezel. Because excessive steering movement is disadvantageous in race use, the steering was limited by adding material to the stopper. Although installing a steering damper was allowed, the team had decided not to. If the rider thought it was needed, it would be easy to install afterwards.
The team thought about the suspension. But pressing the bike, we concluded, the rear was alright, but the front fork could have been stiffer. We studied fork oil viscosities to discover alternatives to original oil and speculated on changing the oil level and front suspension height. After having a few cups of coffee, we thought best not to do anything before the bike had been ridden for the first time.
The cooling system was drained and flushed of original coolant. Distilled water and Water Wetter, which has anti-corrosive agents in it, were used as coolant. The tank was fitted with security foam. The final touch was securing the brake calipers, oil fill and drain plugs and oil filter along with installing a shark fin in front of the rear sprocket. A few broken drill bits later all the bolts were re-installed and secured with steel wire. Before fuelling, we weighed the bike, and discovered it had lost exactly 10 kilos, now it weighed 148 kg. The next stop would be paint shop.

The fin prevents stuff like fingers from getting caught between chain and sprocket. 

Later I had a chance to test ride the Kawasaki on Alastaro Circuit. The bike was a positive surprise, riding it was a blast! The cold weather caused a bit of problems with the tyre pressures, but as I gained trust to the front, throwing the bike from side to side was great fun.
The suspension worked well, and the front wasn’t the least bit too soft, and the bike felt balanced. The handling is excellent in comparison with the engine performance and I managed to corner at quite high speeds. The only problem was limited ground clearance as the suspension compressed quite a bit under my 100 kilos of purse muscle. I suppose 12 year old racers don’t have the same problem.
The engine is fun and revvy. You actually must use high revs in order to go fast, and the usable power band is somewhat narrow, which means active gear changes. The only weak link is the brakes. Although the moderate speeds mean you rarely need to slow down, the lever softens and brakes start to fade after just a few laps.
However, the limited power doesn’t allow mistakes at all, which means a young rider will not only learn to ride, but also have fun while doing it. And besides, it doesn’t matter how many horsepower you have, as long as it’s roughly equal to what the competition has…