Well, I took the old 500 for another ride this last weekend and ran into a little problem. Fired the bike up for the last ride of the day and was hammering pretty fast over some whoops when all of the sudden the bike just bogs once I let off the gas and tried anything over 1/4 throttle. I knew immediately what the problem was since this has happened to me on this bike twice before. A broken carb needle, which I recently figured has happened about 16 months of pretty consistent riding. Not the worst thing since it won't leave you stranded, but if I threw down money to enter a race and got a DNQ on one of the most reliable bikes around, that would suck. The strange thing is that the needle brakes right under the the bottom most groove every time. I have the needle clip in the 3rd groove. I have an older picture (not the best picture, but it can be zoomed in for detail) from when I had the needle and slide out last time here:
http://s1246.beta.photobucket.com/user/rjhansens/media/IMG_0492.jpg.html.
Since this is an Ex Team Green KX500, I have no idea if anything was modified that I'm not aware of (I know all the jetting specs because they write them on their carbs, but was the slide modified, the non-replaceable needle jet modified, etc?), but in addition to a new needle and clip, I'll by the slide this time. The slide seemed fine when I had it out, but is it possible for these thing to wear enough to cause a problem? Could the carb body be worn? Just from the naked eye, everything looks perfect and the bike runs exceptional until the needle breaks. One key thing I feel I should mention is that every time this has happened, the throttle doesn't hang up at all, and this just occurs all of the sudden. So, even though I'm replacing the jet needle, if the needle jet is tweeked I thought this would make it hang up at least once during this much riding.
The first time it happened I wasn't too concerned because I figured maybe it got a little tweeked when someone tried to put the slide assembly on with the fuel tank on the bike. The second time, I inspected everything very well and couldn't find anything wrong, and just figured maybe it was a fluke and threw an extra clip and needle in my camelback in case I got stuck out in the hills. Now, I'm going to chase it until it's fixed, but I'm just confused since I've never heard of this happening before and I was a career mechanic back in the day. Raced thousands of desert miles with a few clubs and still, haven't heard of this.
This is the only problem I've had with this bike after owning it for about 4 years with no rebuild. We're talking a lot of hot, dusty desert miles I know I need to do it soon, but it's just so fun to keep riding! Just keep eating up gas, grips, and tires. Please give me your thoughts.