Kawasaki KX80, 1986-1987 Fork Springs (Pair):
SPRING-FORK L=535mm, K=0.33kg/mm, (2 PCS), 44026/FS5433
As for most 80cc motocross machines of the 1980s, the KX80 was designed to suit the median age, weight and height characteristics for the relevant class (boys 9-16 years of age) and median weights of 40kg/90lb (Small Wheel) and 50kg/110lb (Big Wheel). In addition, the KX80 front fork was woefully under-sprung in 1986 and 1987, so we got to work and engineered stiffer springs. In fact, this is the stiffest spring you can possibly put in these forks. Period. At least not springs that will coil-bind, buckle or fail under stress.
Kawasaki listed the stock spring rate at 0.26 kg/mm (0.28 kg/mm for Big Wheel model). We measured 0.22 kg/mm. This means that the stock springs were designed to suit riders weighing 30kg (66lb)! Our springs measure 0.33 kg/mm which will suit riders of 60kg (130lb) and up depending on your riding style, age, skill level and the type of riding you will be doing.
We tested various combinations of spring wire type, diameter, number of coils and spring lengths to produce a spring that met all performance criteria. These springs will not coil-bind, buckle or fail in service.
Due to the extended length of these springs (535mm), the stock spacer (#92026) is not required however OEM recommends retaining the stock spring guide (#44028) to ensure that the spring remains straight during service and to protect the fork cap from damage.