I have been trying for 4 years to get this sled right. it is a 1978 enticer 250 with the Keihin carb. This machine just will not start. I can get it to start if I take the plug out and put some mixed gas down the cylinder. I need to do this 2 times before it will run. Once running it is perfect and will restart every time until it sits for an hour or more. Then nothing. I have rebuilt the carb (2 years ago), cleaned it a million times, adjusted the bolt on the bottom to 5 1/4 turns out. Checked the choke which is free and seated properly. checked the throttle cable which has 1/8 inch of free play, replaced all fuel, oil and pulse lines. I just don't know what to do. I'm about to put a ball type primer in the fuel line to see if that will help. Does anyone have any other ideas? I would really appreciate any help I can get.