2000 426. Found head gasket was blown. I tooked my head down to my local machine shop, head was ok. Replaced the head gasket and got everything back together. The only way to get my bike to start is to pull out the hot start knob on the carb. When it does start it only idles for about half a min. I took the carb apart cleaned it, set the float level and set the pilot screw as per my yamaha service manual. I dont think my cams are off, I have rechecked them and they look good. Sounds to me like I have carb problem,Any ideas?