Fork Gaiters


Bought an '89 EX250 in the fall of 2010. Came with crunched up fairing, gunked up carbs, but otherwise "put away in running condition" 7 years previously, according to the previous owner. One additional problem that cropped up was leaky fork seals.

Fork seals fail because of wear, caused by rock dings, dirt and bugs on those nice, shiny exposed fork tubes. They are in theory supposed to be kept clean by the 'dust seals' above them, but dust seals don't clean all that well and offer no rock protection.

So besides new fork seals, the Ninja gets custom fork gaiters. The tops of the  fork sliders measure approximately 56mm diameter, fork tubes are 36mm. There's about 170mm of space between the slider and the lower triple clamp on the Ninja.

Bought a pair of aftermarket gaiters (probably for a CB400), nominal 56mm inner diameter at bottom, 33mm at the top and 200mm long from eBay U.K. (11.96, shipping 2.50). I trimmed off everything above the 16th pleat.

From orange juice jug plastic, I cut two large washers, 41mm ID, 53mm OD to fit inside a gaiter pleat. Trimmed a couple of 41mm grommets to ID 36mm to fit between the fork tube and the washer, mostly to prevent rattling. The gaiter bottoms are a slip fit on the sliders, held in place by stainless hose clamps (eBay UK 50-70mm dia., 8mm width, 2.50, shipping 2.50).

The dust seals are not used as they add stiction.

 Although the EX250 manual says fork travel is 140mm, I measured only 130mm when I had them apart to replace the seals and oil. The installed gaiter length is 170mm and the pleats compress to 50mm, so if the fork is ever fully compressed, they might distort a bit. The gaiter bottoms look pretty good, the tops are up near the lower triple clamps and can't be seen because of the fairing. The installed pic also shows the braided stainless front brake line (white).

This mod has now been done with mounting variations to 4 bikes (e.g. Concours gaiters) over 37 years to fend off bugs and small rocks, haven't had a fork seal leak after gaiters have been installed.

To reproduce this installation with some other type of gaiter, beware the outside width dimension is critical to prevent the pleats rubbing against the inner fairing as the bars are turned. Outside diameter of the pleats on these gaiters is about 61mm, giving about 6mm clearance between gaiter and fairing.