The kickstarter has a ratchet-like mechanism to engage the kick lever. Over time the pawls on the ratchet can wear, particularly if you are prone to frantically stabbing at the kicker if you stall out during a ride. Mine has been marginal for some time now and I have to be careful when I kick it over or it slips. Oil viscosity and oil level have an effect. Typically it’s worse when the bike is cold. If you have this problem and are not ready to tackle the repair yet there are a couple of things that can help: Don’t overfill the transmission, and use a lighter weight oil. This is an instance where ATF is better than Mobil 15w-50.
I’ve had he parts to fix it for a few months now, but have been waiting for winter. I dimly recall they were in the $50-$100 range. You have to pull the right sidecover and the clutch to get at it.
I got the same problem with my 2002 kdx 200- getting ready to get in there and see what the problem is soon-very annoying as this problem happened to me on start line of a hare scrambles race (race was a dead engine start). Everyone else on line started their bikes and was in the woods and Im still sitting there kicking the thing and it wouldnt engage-still finished the race o.k.