Just returned from a 1400km trip. A persistant problem I have had with my Viper is the Power Valves start to stick much before they should. Since new (2002 model) my valves start to stick at about 600km. By 1200 they are totally stuck. This is no problem around home, I just clean them frequently, but is annoying on a long trip. I always keep track of my mileage, fuel and oil consumption. Last year I was using oil at almost 80:1 (very lean) and got 16.5 miles/CAN gal. The valves started to stick at 600km. So this year I adjusted my oil setting and the oil/gas consumption changed to 66:1. The valves didn"t start to stick untill 850km. Do any of you Yami gurus have any suggestions? Should I adjust the oil setting again to try to get a 50:1 mix? I am using Yamalube, and I know I could possible improve the situation by changing to synthetic, but I also know lots of Yamaha owners have good luck with the Yamalube. Or is it that they don't notice the performance change when the valves start to stick?