Here's the facts: 2000 YZ426F About 4000 ft elevation, About 60 Degrees out, Stock jetting; 42 pilot, 162 main, stock needle, 2 turns out on fuel screw. Bike runs really well. I was climbing a sand hill, 3rd gear, half throttle. When I get to the top and stop, I notice a slight amount of smoke coming out of the exhaust. After a few minutes of running, not climbing the hills, there is no smoke. It only happens after climbing the hill, under obvious load, and goes away. Is this a jetting problem? Is it loading up while going up these hills and then burns off when run "normally" again? Or is there something else I should check out? Any input would be appreciated.