Hello there!

I'm riding a KLE 500 myself, but I'm also hanging around in an GPZ500 forum (Ex-500.com - The home of the Kawasaki EX500 / Ninja 500R - Index). Since I couldn't find any information regarding the year of the bike, I'm going to list what you might have to check for BOTH generations.

First generation

The first generation was made between 1987 and 1993, and the second generation from 1994 and onwards. OK, let's assume you are going to buy a first generation bike. The cam chain tensioner is, from what I've read, junk. Getting a second generation cam chain tensioner is recommended (they fit!).

The first generation's flywheel magnets CAN get loose . They are "glued" on. On the second generation bike, they are actually kept "inside" a metallic wall, which makes the second generation flywheel a lot better.

The transmission is also better (can't get into any exact details here why, but you can find more information about this at the forum I linked above).

Second generation AND stuff that applies for all GPZ 500 bikes

If you are buying a second generation bike, then skip the last previous section completely!

However, since these bikes are using CV-caburetors, I would check if the bike is using POD filters or the original airbox, and if it is dynojeted. In general, these bikes are jetted very well from the factory already, and a dynojet kit can (and usually will) make it worse, and same with the airbox. Some CV bikes MIGHT benefit from using pod filters, but not this one.

In my experience, most problems with this bike are usually related to the carburetor, which is why I would start there. Check for hesitations when the bike is idling, half throttle and full throttle.

There are of course more things to check which can also be applied to most bikes, but the things I've mentioned above is something that tends to come up from time to time in the other forum.

If you want to gather more information about this bike, then do yourself a favour and register on the GPZ-500 page I mentioned earlier. You can find a wealth of information there!

Regards,
Mollrik