Authored by: Eric
Gunnerson.
Friday, March 24, 1995
Updated November 20, 1996
HTML'ization by: Matt Dennie.
Having typed the same thing over and over and over, I decided to spend a little time and put together something more substantial. Ideally, this would be integrated with the other FAQs into a single document. Anyway, please feel free to comment on the information, or to fill in those areas that I've left blank.
The EX500 (or GPZ500 to those outside the US) is one of the few bikes that was created specifically because of reviewer feedback. When Kawasaki first introduced the 454LTD (with an engine derived from the Ninja 900), the reviews were good, and several reviewers said, "Why don't you put this engine in a sport bike?" So they did, enlarging it to 500cc in the process, and releasing it in the 1986 model year.
Since then, it has become Kawasaki's best selling bike, and was produced unmodified (is this true?) until the 1995 model year, when an updated version was introduced, wearing the Ninja 500 moniker.
The EX has been so successful because it has a lot of advantages:
In other words, the EX is the perfect first bike. With a few modifications, it will also serve the more advanced rider well.
Internal Ratio MPH/K RPM MPH@Redline 1 2.571 4.1 45 2 1.777 5.9 65 3 1.380 7.5 82 4 1.125 9.3 102 5 0.961 10.9 120 6 0.851 12.3 135
(to make comparisons easier, I've only listed those that are different from the previous model. There may be differences that weren't apparent from the specs.)
Internal Ratio MPH/K RPM MPH@Redline 1 2.571 4.1 45 2 1.777 5.9 65 3 1.380 7.5 82 4 1.125 9.3 102 5 0.961 10.9 120 6 0.851 12.3 135
My top modifications would be aftermarket tires, brake line, brake pads, front fork springs, and seat.
One doesn't expect much from the stock tires of a budget bike, and the OEM Bridgestones live up to those expectations. 'Greasy' is an often-used description. If you're looking for the best spot to spend your money, this is the first item to upgrade. In other words, "Dump the Bridgestones before they dump you". The earlier EXs ride on 16" wheels, which are relatively rare these days, so tire selection is limited - especially in the stock sizes. There are, however, good choices out there. The general consensus is for the Metzelers, but the Dunlops are a bit cheaper.
The ME33 is the choice for the front. For the rear, either the ME55A or the ME99A is fitted. The most recent advice is to go with the ME99A for the rear as its a more sporting tire, though many with ME55As have been satisfied with them. Mileage on these tires is good, and grip is excellent. A 110/90 is normally fitted on the front and a 130/90 on the rear (no 120/90 available). A 120/80 is also an option for the front, though most who have chosen it have been less satisfied with it.
The Dunlops of choice are the 591 series, with a 110/90 up front and a 130/90 on the rear.
The stock seat is made our of injected plastic. This material isn't particularly strong, so it is molded with ribs in it to increase the strength. After a long ride, these ribs often imprint themselves into your backside through the seat foam. While there are others, Corbin is the leader in aftermarket seats, and their EX offering is a vast improvement - the seat pan is made out of fiberglass, with no ribs. The seats sold by Lockhart are made by Corbin. Corbin can also vary the thickness of their seats if you want to change the seat height.
There are several upgrades that can improve braking (both power and feel). Aftermarket pads are a good upgrade, and EBCs are one of the good choices. Replacing the stock brake line with a stainless-steel or kevlar wrapped teflon line will get rid of any mushiness due to the stock line. Russell is one of the companies that makes lines that will bolt on. A good bleeding is also important - Lockhart makes a banjo bolt (the one that connects to the master cylinder) that has a bleeder on it, and this makes bleeding much easier. Of course, use good fluid and change it every year. Also, check out the suspension section - new front springs make a tremendous difference.
TBA
TBA
The front fork of the EX is a bit small, and can twist under load - especially under hard braking, because the load is only on one caliper. A fork brace will reduce this twisting and improve the bike's behavior. TeleFix makes one for the EX.
There are several options here. There is a factory chin fairing that covers the lower half of the motor. This is relatively inexpensive, and easy to install. It does, however, reduce the ground clearance slightly (I've got the grooves in mine to prove it). There are also full fairings that cover the entire engine from Lockhart and Targa. (We need more info here).
There are also fender eliminator kits (sometimes known as 'trick kits' that replace the rear fender with a small bracket that holds the license plate, improving the looks of the bike. Note that these are technically illegal in most cases (though I haven't met anyone who got written for it).
As with brakes, the suspension isn't the highest quality. The front is undersprung, the rear is weak and wears out quickly, and the only adjustment is preload on the rear shock. For the front end, new fork springs are an easy and inexpensive upgrade - Progressive Suspension makes a good set. You *may* need to change the fork oil at the same time. With the Progressive springs, the front end won't bottom out even when you brake hard. If you have hand tools , this is a pretty easy modification to make, and only takes a few hours.
For the rear suspension, the fix is a new rear shock, but that's quite a bit pricier.
Clutch cable failure has been fairly common on EXs. Whether it is due to the sharp bend the cable takes or bad manufacturing isn't clear, but I've had 2 cables break on mine, and now replace the cable every 12000 miles (whether it needs it or not). If the cable seems to be stretching or not so smooth, it may be time to replace yours. Cut the old one open to see if you were right. A little lubrication will help here as well.
The clutch isn't overtaxed by the power of the engine, but because the EX is a twin, it doesn't pull smoothly until about 3000 RPM, which is roughly 15MPH in first gear. If you do much stop-and-go riding, you'll be spending a fair amount of time under 15 MPH, and therefore slipping the clutch. Mine got grabby after 11000 miles, but the replacement (aftermarket) has lasted over 30000 miles.
Authored by: Patrick Richardson.
October 29, 1996
Updated November 20, 1996
The list - in order of importance...
The stock EX-500 wheels and suspension aren't good to race with, regardless how much horsepower you have, you can't use it with the stock set-up.
Option one is to put a late 1980's 600 Katana front end on with a late 1980's Katana rear wheel and Fox shock. The upside is it is cheap and easy, the downside is you are still stuck with older technology tires. This will work great for you if you don't want to be the #1 rider in your class, or if the class is not too competitive (i.e. you don't have to race against open or middle weight machines).
Option two is to go for a F2 front end with a ZX-6 rear end. I haven't ridden one personally, but i've seen the results from a friend's EX and it looks pretty good. The down side here is cost and some significant machining for the rear end, but the plus is that you can use modern rubber (which may cause its own problems-- i don't know if the EX chassis can handle the grip).
Either option uses the appropriate master cylinder and gives the EX some serious brakes.
Reducing the weight is important to any race bike. Good things to try are going to lighter weight body work (supposedly a Hawk tail section can be made to work without too much trouble). I would stick to reputable manufacturers for your body work. More weight can be lost by removing parts of the frame, but you should review your plans with someone who knows what they are doing. Removing the starter and charging system give other strong gains, but you then have to worry about starting the bike and keeping fresh batteries (all ok if you really want to win).
After you've got the suspension right, major gains on lap times can be made by motor work. First, using better carburettors will gain some power. Suzuki slingshots are a good cheap option or Keihen 37mm CR's if you want to go for broke (in more ways than one). The D&D exhaust system seems to work ok for making the exhaust flow better without sacrificing too much ground clearance (you have to tweak it a bit to have good side clearance, but it is all done in the installation process- no modifications).
It is said that there is no replacement for displacement, and this holds true for the EX. Going to 525cc is easy with a bore and pistons, but much above that and you need to resleeve. EDCo and Cosworth both have options for the EX that work.
The final big fix is to improve the flow (which is probably the single biggest power improvement). EDCo and HO Motorsports both have had good results with bigger valves and flow work.
There are many more tricks that can be done inside the engine, but most of these only produce subtle gains for the really fanatical.
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