apache snow-FSO wrote on 04/05/13 at 18:32:31:I have a K&N filter and stock exhaust. I raised the needle .030, put in a 55 pilot with the fuel screw turned out 1 and 3/4 turns, and a 147.5 main. The bikes runs really good with this setup.
I tried to stay with the stock 52.5 pilot but at 30 mph and light throttle it would surge and thats with the fuel screw turned out nearly three turns. I also had to leave the choke on a long time. Seems it took forever to warm up. Going to a 55 pilot solved having to leave the choke on a long time and cured the surging at light throttle.
I installed an O2 sensor and worked on my jetting. I had a stock air cleaner and a Dyna muffler at the time. I tried a 55 pilot and 152.5 main and started riding and adjusting. After fussing around I ended up with a 150 main and a 50 pilot and the jetting was almost perfect.....but like yours it had a lean stumble just off idle and would surge. I took one washer off the top of the needle so that I only had 2 washers, and this raised the needle.....and it runs reallllllly good. The O2 sensor shows tha the mixture is really good at all throttle settings an the bike runs so much better.