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The 500 Ninja
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The Kawasaki GPZ500 / EX500

Some machines you desire, lust after, would die for, this isn't one of them. I grew to appreciate the little Ninja, and it gave me its all, but it never lit my fire. It proved to be an extremely competent machine. This bike was a daily hack for 5 years, and is still running today (year 2002 - see foot of page).

Details

The Kawasaki GPZ500, also known as the EX500...
  • Is a 2 cylinder 4 stroke motorcycle
  • Displaces 499cc
  • Has a single disc up front, a drum at the rear
  • Electric's contained gremlins
  • Engine parts made of Kawasakium, a rare form of Aluminium
  • Handles excellently
  • Has a comfortable seat
  • Has a 4 gallon (Imperial) fuel tank
  • Gave between 25 and 60 mpg
  • Completely green - runs on unleaded
  • Went 135mph, with following hurricane and down the steep part of a cliff
  • Could cruise at 90mph all day
  • Would wheelie if abused enough
  • Could be made to slide and stay rubber side down
  • Introduced in 1985, still in production with updates

Failings

There is one big problem with these Kawasaki's, and its a problem all the late 1980's Kwaks had: they suffered from Carburetor Icing. As fuel formulations changed and manufacturers improved the quality of the vacuum in the intake tract, they stepped on a hidden problem: the water in the fuel froze out in the intake tracts. If it happened badly enough the engine would stall, even from high speed. There are several fixes including fuel additives, carburetor warmers, and body panel alterations. The "summer" of 1985 was miserable, it rained most days, with the high humidity I suffered terribly from constant stalls. The bike would run roughly, then draw to a standstill. The engine would run but would be so feeble it could not pull the bike. Turning off the engine for a few minutes was all that could be done. I added cardboard panels leading back from the radiator to cover the carbs. This helped. It looked a real mess after a winter or two, though. Eventually, in 1998, Kawasaki were forced into a rare motorcycle recall. They replaced the carburetors with items that had engine coolant flow ways drilled into the bodies. As my bike was an early model, the replacement carbs were not setup properly and I often wished for the old carbs back again, they just worked better!

The front disk is a single rotor item, this has been made quite thin and light. Under sustained abuse the disk cracks or warps. I had one that cracked, becoming a large spring washer, and two that warped.

Consumables like tyres and brakepads wore out with indecent haste, I doubt I, moi, could be the culprit!

The starter relay has an appetite for fuses, it burns the little legs off the fuses. This occurs as a consequence of the starter relay failing.

Strengths

The 500cc motor is a gem. It runs and runs. It has to be revved a bit to keep it above the lumpy low down part of the rev range, but once in song it is a very smooth performer. It made very useable power all the way to its stratospheric 12,000 rpm redline. I have developed mechanical sympathies over the years and spinning any engine to 12,000 rpm is tough, but this one took it and seemed to thrive.

The handling was superlative. It tracked well, turned on a dime, and generally gave lots of feedback while remaining very stable. When fitted out with premium tyres I was able to fling the bike about hard enough to cause it to slide both ends - on the road. It did this without a display of ingratitude.

It managed to be comfortable enough to handle one-up touring, taking me to the South of France in the company of two 1100cc bikes. It was adaptable to many chores. It was a great commuter bike, but also served well as a sport bike and sightseeing tool.

Tried and Tested

Tyres

The original fitment were Japanese Dunlop's. They were effective tyres, but replacement showed them to be a detriment to the real qualities the bike possessed. I tried Pirelli Phantoms, but they were old tyres by the time this bike came along. Then I happened upon Michelin A48/M48 tyres. These were stunning. They allowed the bike to be leant till the pipes were dragging, and worn through. Removal of the lower fairing was necessitated.

Exhaust

The original Kawasaki pipe was good for quite a time, several tens of thousands of miles in fact. However, when they went I put on one of the few replacements then available on the market, a Motad 2-into-1 pipe. This was quiet and seemed to beef up the mid-range a tiny bit. Unfortunately, after the carbs were replaced, the pipe made the bike run quite lean. I would recommend rejetting.

Seat

The original seat was adequate. I never needed nor located a replacement.

Plugs

GKN.

Oil and other consumables

I replaced the oil regularly at about 5000 mile intervals. I always replaced oil and oil filter at the same time. I always used a Kawasaki filter. The oil could be any old slop that had the right numbers and seemed slippery, but it seemed to prefer the thinner stuff.

Brakes

Ugh, the brakes! These were a pain in the neck. As noted above, the rotors would go boing! too often, and replacement was tricky (correct torque became important). The front pads also exhibited phenomenal wear rates. Some of this is due to the way Kawasaki set the brakes up, some was due to me leaving the braking to the last possible moment, either way, brake pads needed replacement with the front tyre, at about 4500 mile intervals. I replaced the pads with a mix of OEM and Ferodo's. I also replaced the brake hose with an Aeroquip hose, which I had to have custom made.

Suspension

The front forks got new oil on occasion. I filled the front with 20 or 25 weight oil. I played about with reducing the volume too. These forks also got the 1/2" of added preload (a nut added above the spring). At the rear I went bonkers. I replaced the old Kawasaki shock with a fully adjustable racing shock. This proved to be a mixed blessing. It was hard to setup and was not the reliable unit it could have been, requiring a couple of rebuilds, but it did offer awesome control over the actions of the rear wheel.

One odd aspect about the bike is the use of Kawasaki's UniTrak monoshock system. This has a lever arm placed low, under the bike, that handles the proportionality of the compression of the shock. The problem is that this item sits in all the mess thrown up from the road. The bearings corrode and are prone to seize. I was forever greasing the links' bearings, a not inconsiderable effort.

To Round Up

I did over 52,000 miles on this bike before leaving it to a friend, then selling it years later. Today the bike is still running strongly. Kawasaki aimed this bike, in its EX500 form, at the learner market but it is an adept advanced riders bike too. It does not have the out and out stomp of a 600cc bike, but it is light and agile, and has much lower insurance premiums. This is a very practical machine. As I said, it never grabs you, you just grow to appreciate its finer qualities.

The latest News

The old Zed is not Dead! It is now April 2002, I sold the GPZ 10 years ago to the son of a friend. He brought the bike back from the edge of death and has ridden it hard ever since. It now has 86,000 miles (137,000 km) on its bores; this motor still has not been rebuilt, though I understand it now needs some work. Below is a recent photo of it in well used form - it's a working bike, not prone to the whims of polish.

The bike lost its fairing, too many crashes from me and a former girl friend consigned the plastic to the bin, the belly fairing went first scraped off by over-exuberant cornering. The seat unit was replaced because an old crash had damaged the vinyl. The GPZ has now been to most European countries. It is said to be still able to exceed 115mph (with following hurricane and over a cliff edge!) I have not heard how its fuel consumption is doing.

These are tough little bikes, the motors are bullet proof and go forever. If you don't take care of it it will give you a lifetimes use. If you do look after it, goodness knows how long it could last.

Front brake lever by Dali.

GPZ 500, 86,000 miles and still going

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