TOPIC:

Anybody know if these are cartridge forks? States they are thick walled.

577nitro

???

Picture or part number please

Related. I just now saw these YSS cartridge emulator fork valves on Japan Web Bike. YSS PD valve 118-4002

From YSS USA: The new PD Fork Valves give that progressive and controlled feeling of a cartridge fork. Radial computer designed valve housing made of 6061 T6 aluminium for light weight. 65 Rockwell hardened for long life and appearance. Damping adjustable and tuneable to any application. Easy to install. Extremely cost effective. Can be used for On- and Off-Road, Racing and Touring. Fully tested and proven. To suit all brands of motorcycles with conventional forks.
....

Race Tech is quite a bit more expensive, but it is a US company, and can provide instructions in English, help over the phone, and will even do the installation if desired. Oh, and their valves are not plastic

.www.racetech.com/ProductSearch/12/Kawasaki/KZ1000/1977-80

Are the Kayaba forks you are looking at on Web Bike part number 74-604?? These forks are a copy of the Kayaba Superbike forks that Yoshimura sold back in the late 70's and early 80's. They are not a cartridge style fork then. The major difference between stock Kz forks and these KYB forks are the inner fork tubes are of a thicker wall, a better working dampner system, and the major differnece is that the lower fork legs are honed to size, not bored to size. You do not have the massive clearance between the inner and outer fork tubes like the O.E.M. Kawasaki forks do!!!! You change the dampening by weight and level of fork oil. Plus they are air assisted too. All the top Kawasaki and Suzuki Superbike teams used these forks back then.

I have run these forks since back in '80 on my Kz1000 Superbike. THERE IS A MAJOR IMPROVEMENT OVER THE STOCK FORKS!!!! After installing these forks along with my home made double clamp triple tree, I NEVER again had any type of chatter, shake, or wobble after that on my Superbike!!!

Are these the forks you are asking about??


These Kayaba forks on my Superbike.


My home made double lower triple tree.

Dr. Gamma wrote: Are the Kayaba forks you are looking at on Web Bike part number 74-604?? These forks are a copy of the Kayaba Superbike forks that Yoshimura sold back in the late 70's and early 80's. They are not a cartridge style fork then. The major difference between stock Kz forks and these KYB forks are the inner fork tubes are of a thicker wall, a better working dampner system, and the major differnece is that the lower fork legs are honed to size, not bored to size. You do not have the massive clearance between the inner and outer fork tubes like the O.E.M. Kawasaki forks do!!!! You change the dampening by weight and level of fork oil. Plus they are air assisted too. All the top Kawasaki and Suzuki Superbike teams used these forks back then.

I have run these forks since back in '80 on my Kz1000 Superbike. THERE IS A MAJOR IMPROVEMENT OVER THE STOCK FORKS!!!! After installing these forks along with my home made double clamp triple tree, I NEVER again had any type of chatter, shake, or wobble after that on my Superbike!!!

Are these the forks you are asking about??

These Kayaba forks on my Superbike.

My home made double lower triple tree.

YES..thank you, do you know what the thickness is of these over the stock ones? Can you add a emulator to them as well? The OEM's with the Racetech emulators work 100% better and provide real dampening now.

Thanks
577nitro

TexasKZ wrote: Race Tech is quite a bit more expensive, but it is a US company, and can provide instructions in English, help over the phone, and will even do the installation if desired. Oh, and their valves are not plastic

.www.racetech.com/ProductSearch/12/Kawasaki/KZ1000/1977-80

They are nice, and work very well. I have them in three of my classic bikes. My RZ350, Gpz550 and Gpz1100.

martin_csr wrote: Related. I just now saw these YSS cartridge emulator fork valves on Japan Web Bike. YSS PD valve 118-4002

From YSS USA: The new PD Fork Valves give that progressive and controlled feeling of a cartridge fork. Radial computer designed valve housing made of 6061 T6 aluminium for light weight. 65 Rockwell hardened for long life and appearance. Damping adjustable and tuneable to any application. Easy to install. Extremely cost effective. Can be used for On- and Off-Road, Racing and Touring. Fully tested and proven. To suit all brands of motorcycles with conventional forks.
....

This look exactly like the Racetech's, exactly, I wonder if the licensed them from RT. I have figured out a way the tune the rebound, still testing but so far it works better that just changing the oil weight.

577nitro.

Bozo wrote: Picture or part number please

Yes, the one's below that Dr. Gamma has.

For Dr. Gamma:

"I have run these forks since back in '80 on my Kz1000 Superbike. THERE IS A MAJOR IMPROVEMENT OVER THE STOCK FORKS!!!! After installing these forks along with my home made double clamp triple tree, I NEVER again had any type of chatter, shake, or wobble after that on my Superbike!!!"

Sir,
Can you expand a little on maybe what was changed internally on these in regards to the dampening, VS the stock forks? Was it a totally different mechanism ? How did/do you measure the inside diameter of the fork legs? What was it about them that improved and or got rid of the wobbles? Was it the extra stiffness, or the reduced clearance? Sorry to pick your brain, but you'r the expert on these, and actually raced with them.

Thanks 577nitro.

577nitro wrote: For Dr. Gamma:

"I have run these forks since back in '80 on my Kz1000 Superbike. THERE IS A MAJOR IMPROVEMENT OVER THE STOCK FORKS!!!! After installing these forks along with my home made double clamp triple tree, I NEVER again had any type of chatter, shake, or wobble after that on my Superbike!!!"

Sir,
Can you expand a little on maybe what was changed internally on these in regards to the dampening, VS the stock forks? Was it a totally different mechanism ? How did/do you measure the inside diameter of the fork legs? What was it about them that improved and or got rid of the wobbles? Was it the extra stiffness, or the reduced clearance? Sorry to pick your brain, but you'r the expert on these, and actually raced with them.

Thanks 577nitro.

Its been like 39 years since I had the KYB forks completely disassembled, so my memory on the damper rods is pretty much lost. All I remember is they looked very different than the stock damper rods. Never measured the wall thickness of the inner fork tubes. The specs in the Yoshimura catalog said they were of thicker walled tubing. I do remember the O.D. of the inner fork tubes were real close to 36.00 mm's. Most stock inner fork tubes miked in at like 35.90!!!! That is almost FOUR THOUSANDS of clearance between the inner and outer fork tubes!!!!! If you have .004" of play between inner and outer forks tubes, how much more side to side play do you have at the axle!!!!!! These KYB forks were softly sprung in the first few inches of travel, but got progressively stiffer as they compressed. My specialty was late braking and sometimes with reworked stock forks I got into major tire chatter to the point I had to actually let off the brakes to stop it. Which means I missed the apex big time in that corner. Never had that problem with the KYB forks, even when I switched to the Kosman 13 inch rotors with the Lockheed calipers!!!!

Mind you that these forks the inner fork tubes ride right on the outer fork leg. Unlike the '81 and up forks that have those teflon coated bushing the inner fork tubes run on instead. 39 years ago the KYB Superbike forks were state of the art, and were the best available to the privateer road racers like me. If I were to build a legal vintage big bore Superbike today, I would go for the Ohlins 41mm conventional forks. The biggest diameter forks allowed by todays vintage rules!!! They don't allow USD forks in the vintage Superbike class.!!!!