Hello All,
New to the site, so be gentle
I have a 1991 KX 500, all stock, that I'm putting a top end into. I have several questions.
1. When I rode it prior to tearing it down, it didn't have much spunk on mid-top end. I checked for exhaust valve operation, and they were functioning. I also cleaned the jets and they were clean. I cleaned the whole carb thorally. The bike was from my uncle, and it should be jetted right, but it is running a 160 main, 45 pilot, with the needle clip set 2nd from top. The elevation I ride is appx. 6000'. I found a jetting chart, and it looks close. The plug is a little on the lean side, but not bad. During teardown of the top end, I inspected the power valves, and they WERE gummy, but still functioning. Anything else I can look at since I'm this far that will solve my flat mid-top end performance? It starts easily, but during deceleration it kind of "chugs" to a stop. Idle is ok.
2. I have read the outline of power valve re-installation, but am a bit confused. I have the powervalve with the notched top pin on the right side (the counter gear side), and aligned it with the rack, aligning the dots. When I fully close the rack (pushed in) the valves expose some of the exhaust valves, probably half of the outer exhaust port.. Only when the rack is pulled out some do the exhaust valves fully close. Is this to compensate for idle RPM, thus pulling the rack out and closing the valves? I have a sneaking suspicion that this is the reason for the ball bearing mod?
Thanks a bunch for the help.