would-be English translation of the (re)translation in French of the Italian translation of the German original text...
(please feel free to correct my English if you have time : just e-mail me as explained on the main page)

The KLE engine derives from the GPZ 500 S, which comes from the GPZ-1000 RX-engine, except it's only the half of it but with the same head geometry.

Given the respective powers of 130 hp for the GPZ-1000 RX and 60 hp for the GPZ 500 S, obviously the KLE engine is no fully employed.

The KLE and GPZ 500 S engines are nearly identical : the only changes are camshafts, 10% shorter on the KLE, (translator notice : I guess it means shorter in terms of valves opening time) who give a better response at medium rev, as required for an enduro bike, but the power is reduced to 48 hp.

When testing bikes, the effects of this change are obvious : the GPZ is lazy at medium revs, and gives its best between 8000 and 11000 when the KLE is OK at medium revs and is outbreathed at around 8000-8500.

Technical datas confirm the test ride : max torque arrives at about 6500, while max power is given at 8250. If you push farther, up to the red line, power decreases to 20 poor hp at 10800 rpm. Many KLEists will probably never go up to 10500 (300 rpm before the red zone) where there only are 25 hp left, the power you had at 4500. For that reason, no use to reach the red when in 3rd gear or higher (maybe in 1st or 2nd you can get some benefit).

As soon as the tank is put off, one can easily see where one of the problems is : the air filter is undersized (could be compared to a 50 cc's) beacause of the few room and of its particular shape, which doesn't let air freely reach the carburettors.

The standard 34 mm Keihin have a flattened shape and, except for the diameter, are structurally identicals to the Kawasaki ZXR 750's, and for that, they can do the job.

We have replaced the air filter cartridge with a K & N. The necessary tuning (synchronization) of the carburettors is not simple, especially to comply with antipollution norms. You need the help of K & N instructions.

(Translator note : I suppose it was a universal pair, as shown on the photo)

With this, the hp curve is 10% better at any rev speed, with 54hp instead of 48 at 8250. This demonstrates how a poorly designed air filter can alter an engine's behaviour.

(translator note : I'm surprised they change the cartridge instead of modifying the filter itself. I've seen on a forum a guy talking about a second hole in front of the standard one, breathing from the back side of the filter.)

Pag. 3

http://www.dernacken.de/kle-tuning3.html

Even if the 6 more hp can be feeled, this doesn' change the engine behaviour (still this power loss above 8500 rpm). Camshafts are not guilty, as one could think, but the exhaust system is. The KLE exhaust is a 2 in 1 (2 pipes get out of cylinders and meet under the motor), which are wortsly designed. The left tube needs to be 15 cm (nearly 6") longer than the right one to meet the other, after a long way round the motor ! This doesn't work at all ! And it weighs about 10 kg (20 pds). With a Yoshimura protoype exhaust, the power reaches 58 hp at about 8500rpm, intead of 54.

Stock exhaust pipe	Yoshimura

Between filter and exhaust, that is 10 more hp ! But, still better, with such an exhaust, the power doesn't diminish so dramatically in high revs. We still have 50hp at 10500 rpm (only 25 hp in stock configuration).

With the Yoshimura exhaust the bike is 5 good kg lighter (10pds). The price to pay is a bigger noise. To reduce it, we have cut and adapted the stock silencer to the Yoshimura tubes, with the help of a junction tube. The final neglectible power loss is only 1hp.

(translator note : ok, but how do you have Yoshimura making such a special work for you ? + if you get in touch with him, just ask him for another one. I'd prefer it above the engine. And don't forget to ask for a special sump guard, too, I'll find something to modify the carburettors heating system... (just joking)

(2nd note :I guess the original article was written before they add catalysors into the exhaust system.)

(3rd note : the only full exhaust system for KLE I could find on the net was this one : Unfortunately, it doesn't solve the dissymetry problem.)
3rd bis on 2007/07/12 : Now this one (from Arrow) seems to be more adequate, and they claim 6 less kg than the standard system.

Even if this power increase is noticeable and conclusive, we've given a try with another KLE on wich were put the GPZ 500 S camshafts and 2 Keihin 35mm carburettors. Those are the best to be mounted on a KLE and easy to fit. One can get them thanks to « Kawasaki-500-Twin » club (http://www.twin500.de/).

With these new improvements, we get 65 hp at 9250 rpm and not less than 58 hp at 10800.

Pag. 4

http://www.dernacken.de/kle-tuning4.html

With the GPZ 500 S camshafts and carburettors, one must confess the power is at a higher rev, with less response at medium revs, and the best torque is 1000rpm higher than with stock camshafts
(The article then gets to obvious conclusions I won't translate : differences between both version, standard camshafts or not, max speed reaching 200 km/h (124 mph), various demultiplication ratios, front fork hardened with progressive springs, steel braided brake lines).

(translator notice : the previous parenthesis is the end of the italian text I started from)