As I pulled down my first set of Bladder forks from a preproduction KX250 back in August 99 I was curious as to what the maker had intended when he unleashed this modern wonder on an unsuspecting market. At first I thought this was Kayabas attempt at making a "poor mans" dual chamber fork. I was later informed that it was designed to create a speed sensitive air spring similar to that of the sub tanks. The forks were essentially divided into upper and lower sections by two forms of seals at the top of the cartridge. On small (low speed) demands oil/air was supposedly able to bypass the seals, compress the bladder and give the illusion of a greater air volume. On high speed demands the seals were to present enough of a restriction to halt the transfer and create a high oil level feel. Whatever it was supposed to do it didn't exactly appeal to the masses. People complained of deflection, harshness and arm pump.
When testing new bikes if we wish to make a simple change to the compression stack we will turn the whole bike upside down and using an air impact wrench remove the base valves, make the change and ride straight back on the track. This allows the rider to evaluate the change while the previous setting is still fresh in his mind. After a short test session with the new KX we decided to do exactly that. Imagine my surprise when I pulled out the base valve and got showered in oil. Pressure had built up in the lower portion of the fork and air and oil was rapidly exhausted as I removed the valve. Now this was while the fork was fully extended and naturally pressure could only be expected to build even further as the forks were compressed. No wonder they had problems with harshness and deflection. Honda decided also to use the bladder forks on their CR125. After discovering the shortfalls of the Bladder Fork Honda continued to use the product only minus one of the seals. This completely negated any possible advantages of a speed sensitive spring. This didn't stop Honda from using the Bladder Fork in their sales blurb in an attempt to lure unwary purchasers. At least they had solved a problem. We had been performing similar mods with the KX shortly after its inception. Enter the KXF250. After a short stint with the much maligned cylinder valve Kawasaki have opted to head back to the bladder fork for yet another attempt at shooting themselves in the foot. One has to question "How many toes are left on the Jolly Green Giant"? Kayaba have attempted to solve the pressure build up problem in the forks by installing a check valve at the top of the cartridge. When pressure in the top portion of the cartridge exceeds that of the lower, the valve will open and equalise the pressure within the fork. It would appear it is upside down. The pressure still builds up in the lower cartridge area. Any attempt to reverse the valve however would see the system fail completely as oil would escape from the lower cartridge area much easier than it could get back in. After battling with the gremlins of this design for two days I decided to remove the seal from the top of the cartridge to see if this was still the fault of this fork. Well you can imagine my contempt for Kayaba as the rider came back with a grin on his face from ear to ear. Still, I guess this is a step forward however; It's a lot easier to remove the sealing band than it is to replace a cylinder valve. Good Luck
Regards
Terry Hay
When testing new bikes if we wish to make a simple change to the compression stack we will turn the whole bike upside down and using an air impact wrench remove the base valves, make the change and ride straight back on the track. This allows the rider to evaluate the change while the previous setting is still fresh in his mind. After a short test session with the new KX we decided to do exactly that. Imagine my surprise when I pulled out the base valve and got showered in oil. Pressure had built up in the lower portion of the fork and air and oil was rapidly exhausted as I removed the valve. Now this was while the fork was fully extended and naturally pressure could only be expected to build even further as the forks were compressed. No wonder they had problems with harshness and deflection. Honda decided also to use the bladder forks on their CR125. After discovering the shortfalls of the Bladder Fork Honda continued to use the product only minus one of the seals. This completely negated any possible advantages of a speed sensitive spring. This didn't stop Honda from using the Bladder Fork in their sales blurb in an attempt to lure unwary purchasers. At least they had solved a problem. We had been performing similar mods with the KX shortly after its inception. Enter the KXF250. After a short stint with the much maligned cylinder valve Kawasaki have opted to head back to the bladder fork for yet another attempt at shooting themselves in the foot. One has to question "How many toes are left on the Jolly Green Giant"? Kayaba have attempted to solve the pressure build up problem in the forks by installing a check valve at the top of the cartridge. When pressure in the top portion of the cartridge exceeds that of the lower, the valve will open and equalise the pressure within the fork. It would appear it is upside down. The pressure still builds up in the lower cartridge area. Any attempt to reverse the valve however would see the system fail completely as oil would escape from the lower cartridge area much easier than it could get back in. After battling with the gremlins of this design for two days I decided to remove the seal from the top of the cartridge to see if this was still the fault of this fork. Well you can imagine my contempt for Kayaba as the rider came back with a grin on his face from ear to ear. Still, I guess this is a step forward however; It's a lot easier to remove the sealing band than it is to replace a cylinder valve. Good Luck
Regards
Terry Hay