Quote: Coolant overflow tank always empty
The plastic coolant overflow tank under the left sidecover on pre-'95 watercooled bikes will tend to lose its fluid no matter how often you top it up. Why this happens is a bit of a mystery. Some say that it gets sloshed out the small overflow tube. Personally I have wondered if it sort of just gradually vapourises off because of the incredible aeration and agitation that it gets from engine vibes and all the violent heaving around when riding. Don't fight this problem in vain, just run the overflow tank empty and keep an eye on the radiator level, which will stay pretty constant without the benefit of any overflow reservoir fluid.
Some KDX owners remove the overflow tank, but it doesn't hurt to leave it in place to catch and condense any vapour and allow the radiator to suck it back in again later.
Update 7/03: I recently followed a suggestion posted by someone on the KDX forum and bent the overflow tank outlet nozzle upwards slightly to prevent liquid sloshing out. It worked! I was amazed to find the overflow tank full after a very rough day's ride. This is the first time it has retained its fluid. Here's what to do: If you remove your left sidecover and seat, you'll notice that the overflow tank's outlet or breather tube is positioned at the top and sits horizontally. You need to bend this upwards at an angle so that any liquid that slops into it runs back down to the tank. I used an electric heat gun on the plastic tank at the nozzle junction. The heat softens things enough to let you bend the nozzle upwards. Be careful not to pinch off the inside diameter. You have to clear the subframe tubes somehow too. I elected to point the nozzle outwards as well as upwards, and re-route my breather tube so that it now runs around the outside of the frame (see pic). This seems to work fine and just clears the seat and sidecover. That's it.
See this thread for more. To reportedly cure boilover once and for all, use the (expensive) waterless coolant made by Evans Cooling.: Quote
I took this from this guy's site.
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url]http://www.craig.copperleife.com/bikes/kdx/index.htm[/url]
It is true for me .... Dave