So there I am riding away It's -10 deg Celsius and 2700' alt ,of course it's on a frozen lake. on a plowed track similar to a road course twisty with 2nd gear stuff and some pinned 5 gear straights. And the bike wr400 2000 is running just tops for the first 1/2 hour to 45 mins. Then out of the blue when rolling on the throttle at 1/4 throttle the bugger just dies nothin and then at 3/4 ish away it goes. I'm running a Big gun exhaust 48 pilot and 180 main needle jet on the 3rd position. I,m thinking it's the needle is rich and when the bike warms up poof it don't like it. So am I on crack or what. (not for the riding on the lake but the bike stuff) If I stop and take a break and let it cool down a bit then it takes about 20 mins to do it again.