KDX Setting Fork Spring Preload


Dec 31, 1969
KDX TechTips: Setting Fork Spring Preload

In stock form the 1995 to 2002 KDX200/220s suspension is out of balance. The 5.0 kg/mm shock spring is well suited for riders between 170 and 200 lbs while the fork springs are better suited for riders up to 130 lbs. This out of balance conditions raises havoc with the KDX's suspension performance and detracts from an otherwise good handling bike.

Many KDX owners will replace the stock fork springs with stiffer units to bring the suspension back into balance and vastly improve handling. Because, in most cases, replacement fork springs aren't the same length as the original units new preload spacers will need to be installed to properly set the preload.

What 's preload ?Fork spring preload refers to the amount of tension applied to the fork springs. Preload tension is applied by compressing the spring from is fully extended length. The difference between the springs fully extended length and the compressed length is how much "preload" is applied to the spring. Typically KDX owner will use about 8 to10mm of preload.

Determining Preload Spacer Length - Determining how long to make your preload spacer is very easy once you know the fully extended length of your fork internals. Here is a picture of a 1995 to 2002 KDX's fork internals. They are fully assembled and the total distance between where the bottom of the fork spring and the top of the preload spacer seats is indicated. Once we know this measurement we can easily calculate how long you'll need to make your preload spacer to get the desired 10mm of preload. The total length is 539mm - the springs uncompressed length = the length of the preload spacers.

Things to Remember -

1) Remember to measure the total length of your spring with the two end caps installed if you plan to use them. Most aftermarket springs have a larger ID than the factory springs so you'll need to expand the three tabs slightly so they'll clip into the spring and be held in place.

2) Remember to include the two spacer guides in your spacer measurement.

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