Some thoughts on the KX-500

[Albertan]

Hi all, I'm a new member, and I own a 2000 KX-500.  I'm 41, and have raced in the Vet Junior class in the past. 

Currently my bike has a Zip-Ty pipe, and an FMF silencer with a Sparky welded on.  Suspension is stock except for .43kg/mm fork springs, and since I'm transitioning the bike to more of a desert/off road machine, it has Acerbis multiplo handguards and a Works Connection heavy duty skid plate/engine cover.

Now while it is a great machine, and I'll never sell it, I have to admit that there are certain things it doesn't do really well.  It is a long chassis, with older geometry, which makes it very stable, and able to absorb all kinds of impacts without getting unsettled or twitchy.  It is not happy in tight u-turn corners, and can be a bit of a fight in tight stuff.  I think that is just a characteristic of the bike.

The power is amazing, not just because there is so much of it, but because it is everywhere, and pretty linear.  With the big carb, and low throttle settings, I used to find that the bike had a momentary hesitation before reving up out of corners.  This was most noticible when I exited a u-turn corner and then had to clear a jump or carry speed into some whoops.  Compared to a 250 motocrosser, this was noticible, especially an RM250, where the burst was instant.  I think it was a problem with low throttle, large carb and low intake velocities.  I installed a Power Now insert (same one as for KTM 125), and loved the change.  The bike starts easier, and has a lot more response at partial throttle.  Wide open I don't notice any difference, but on a track, I'm rarely wide open and for pulling out of corners, the difference is amazing.  Have any other members made this mod?  What has their experience been?

[Albertan]

I haven't checked the power valves lately, but I tend to doubt that as a problem.  The Power Now cleaned things up immediately, which leads me to think things are induction related.  Also, the plug comes out coffee coloured (and did before the Power Now insert), and we aren't talking about a huge bog, or a stumble in the engine, just that before the mod, it wasn't "crisp", whereas now it is.

In Calgary, where I do most of my riding, we are at 3,500 feet above sea level, and I did find that I needed to lean things out from the stock jetting.

[Albertan]

Hey BDI, don't want to get into an extensive debate with you, and I appreciate your comments on jetting.  I found that I didn't have to change the main (though unless I'm riding in the wide open spaces or desert I don't really get onto the main for more than a few seconds at a time).  Needle I didn't need to play with, but the stock pilot was way too rich and I need to play with the air screw depending on temperature.

The Power Now doesn't make any difference at wide open throttle, but the difference at partial throttle is noticible, and documented.  I never felt I needed more power, but I wanted, and got, more responsive power.

I've heard about others running reed spacers to help low end/partial throttle, but I'm happy with things now.  I'm now thinking about adding a GPR or Scotts steering damper.  Thanks for the feedback.