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11 Posts
Hy everyone!
I write this article to share with all of my tuning, and developments of my old 1st gen gpz 500 s.
The background live of my bike: 1993 1st gen gpz 500 s, with a 20 kw choke. The last owner had the tipical selfkill gpz issue. The flywheel magnets fly away and kill the bikes engine. So when i bought it it have an gpz cyilnder and new pistons, and er-5 cylinderhead and camshafts. So now the bike now somewhere 35 kw. Flywheel is came from mitsubishi and its have 1 round magnet.
Modifications:
Carb: GPZ 500 s 1st gen needles with 130 main jets. Better low end torque and throttle reaction. No more hp or higher top speed
Airbox: I make 1 more 1 inch hole in the airbox, like the FOG mod, but this not the fog mod, because i not buy the K&N air filter. i buy a new original. Better throttle reaction every RPM.
Exhaust: The stock has the wisthleing issue. Very irritating. Change it. I like to order a used er-5 2-1 exhaust to fit the cylinder head and the camshaft, and they send me something else. It was a 1986 gpz 900 right side 2-1 exhaust manifold without the muffler. Hmm, what ever try it. i install it. Its fit, with the original brace and i buy for it, a 2004 kawasaki z750 muffler. With these two modification i had an other bike. More torque, and a different sound. This exhaust havent got that piece of tube witch connect the two pipes before the muffler. Its sound deaper, and firing back when its hot and i use engine brake.
Chain sprocket: After these modification i have a very good bike, but i dont like high rpm, so i buy a 17 teeth front sprocket with stock rear and a new chain. Difference: 5000 rpm--> 100 km/h 9000 rpm 180 km/h GPS, this is the top speed, but its in every time. Less fuel its need.
Rear: The drum brake was terrible. and the swingarm was heavy. The 1986 gpx 600 swingarm is fit. So change it. swingarm, wheel (very simila to the original), sock absorber, disc brake. Much better in the corners alone or with passenger. BUT--> now the front is sh.t.
Front: Progressive springs, 15 w fork oil. and a fork brace. Now equal good the rear and the front suspension. Much sharper the hole bike, feels lighter and younger. Better cornering in high and low speed to.
I have an other bike. A Yamaha SZR 660 wich is a race bike. When i bought it I realized that the GPZ is not a good bike, but i love it, so i don't like to sell it. So i developed. Now the difference between the to bike's is not a grand cayon just a ditch. Its still have difference, because i tuned the GPZ for myself, and the SZR it s a factory racing bike, but with better technice i can catch the SZR and my wife in the mountin roads.
This was how i tuned my GPZ to be a good bike. Now its much better than i bought it. And i think i never sell it. If its ever breaks down (I dont think) I'll buy KLE 500 and use its part, and sell others to live in other old and good EX 500 bikes.
Thank for reading.
Pete
I write this article to share with all of my tuning, and developments of my old 1st gen gpz 500 s.
The background live of my bike: 1993 1st gen gpz 500 s, with a 20 kw choke. The last owner had the tipical selfkill gpz issue. The flywheel magnets fly away and kill the bikes engine. So when i bought it it have an gpz cyilnder and new pistons, and er-5 cylinderhead and camshafts. So now the bike now somewhere 35 kw. Flywheel is came from mitsubishi and its have 1 round magnet.
Modifications:
Carb: GPZ 500 s 1st gen needles with 130 main jets. Better low end torque and throttle reaction. No more hp or higher top speed
Airbox: I make 1 more 1 inch hole in the airbox, like the FOG mod, but this not the fog mod, because i not buy the K&N air filter. i buy a new original. Better throttle reaction every RPM.
Exhaust: The stock has the wisthleing issue. Very irritating. Change it. I like to order a used er-5 2-1 exhaust to fit the cylinder head and the camshaft, and they send me something else. It was a 1986 gpz 900 right side 2-1 exhaust manifold without the muffler. Hmm, what ever try it. i install it. Its fit, with the original brace and i buy for it, a 2004 kawasaki z750 muffler. With these two modification i had an other bike. More torque, and a different sound. This exhaust havent got that piece of tube witch connect the two pipes before the muffler. Its sound deaper, and firing back when its hot and i use engine brake.
Chain sprocket: After these modification i have a very good bike, but i dont like high rpm, so i buy a 17 teeth front sprocket with stock rear and a new chain. Difference: 5000 rpm--> 100 km/h 9000 rpm 180 km/h GPS, this is the top speed, but its in every time. Less fuel its need.
Rear: The drum brake was terrible. and the swingarm was heavy. The 1986 gpx 600 swingarm is fit. So change it. swingarm, wheel (very simila to the original), sock absorber, disc brake. Much better in the corners alone or with passenger. BUT--> now the front is sh.t.
Front: Progressive springs, 15 w fork oil. and a fork brace. Now equal good the rear and the front suspension. Much sharper the hole bike, feels lighter and younger. Better cornering in high and low speed to.
I have an other bike. A Yamaha SZR 660 wich is a race bike. When i bought it I realized that the GPZ is not a good bike, but i love it, so i don't like to sell it. So i developed. Now the difference between the to bike's is not a grand cayon just a ditch. Its still have difference, because i tuned the GPZ for myself, and the SZR it s a factory racing bike, but with better technice i can catch the SZR and my wife in the mountin roads.
This was how i tuned my GPZ to be a good bike. Now its much better than i bought it. And i think i never sell it. If its ever breaks down (I dont think) I'll buy KLE 500 and use its part, and sell others to live in other old and good EX 500 bikes.
Thank for reading.
Pete