So I went riding yesterday with my wife and the KX was running just fine. Today I went out with my brother and it was running great for about a mile on a gravel road and then really started bogging down bad and would barely run.
This happened while I was running 2nd or 3rd gear at mid range rpm. The bike will start up just fine and idle with no problem. Once I try to give it a bunch of gas, even in neutral, it almost stalls out on me. I rode the bike around quite a bit thinking that my plug had fouled but that didn't seem to be the case. If I get the bike up in the mid rpm range with the clutch in then release the clutch I am able to cruise around at a pretty good clip, but as soon as I get out of this sweet spot it will start sputtering. If I really get on the gas it will completely bog down and stall if I leave it at WOT.
I pulled some of the bike apart. The spark plug looks fine and is gapped correctly with a strong looking spark when turned over. The air filter was dirty but not bad enough to cause real problems. I checked the carb out with what little carb knowledge I have and it looked fine. There was nothing clogging either of the jets and the float was moving slowly (note: I don't know much about carbs, that's why I took it in to have someone else tune and rejet it last year). I pulled the exhaust pipe off and checked piston and cylinder from the port and it looked ok, also checked the movement of the KIPS and it was moving smoothly.
I need a little help in diagnosing this problem. I have replaced the top end myself so I am fairly compentent in the shop, but I just don't know enough to figure out where a problem is coming from.
I also checked the fuel flow from the tank by running it into a gas can and it didn't seem restricted. I have been having problems with the exhaust on the bike as well. The front mount broke so the pipe was rattling around, could excess air be getting sucked in through the exhaust?
