Join Date: Nov 2009
Location: Lander, Wyoming
I'll suggest that your running issue may be two-fold.
The KLR carb is of Constant Vacuum design, also called Constant Velocity design. The Exposed air filter has lowered the overall operating Vacuum thru the carb throat and the slide spring and the vacuum hole in the bottom of the slide were not designed to operate at this much lower level of vacuum. You may have to convert to a common slide valve carb to properly calibrate and eliminate the issue.
The mid-range needle fuel mixture will be leaner due to the easier air flow thru the exposed air filter. Are you using a KLX650 adjustable needle or other adjustable needle?
Trailing throttle After-fire popping in the exhaust can be a sign of a Bad gasket at the cylinder head / exhaust pipe manifold. Or possible a pin-hole in the little enrichener diaphragm on the LH side of the carb. Also do you have the AIS air port Blocked Off properly/completely next to the spark plug on this 2014 engine?
Modify at "YOUR OWN RISK"!
Still riding my 1987 KL650-A1. 85,000+ miles & counting