Re: Compression problem or carb problem?
I agree with laddies. even if the motor is off time, or the fuel pump was wacked, you sould still feel vacuum if you put your hand over a carb. <br /><br />i believe the reed valves are suspect. I know its a stupid question but are you sure the throttle shudders were wide open when you checked for vacuum at the carbs ? Or when you ran the compression test ? <br /><br />Also dont forget, a compression test's results are priceless, but what it does not show is a lack of primary compression. The crankcase has to be alternatly under high and low pressure. after the intake port is closed by the piston, further downward travel of said piston causes the trapped mixture to be pressurized so it can rush quickly into the cylinder when the scavenging ports are opened. <br /><br />Up piston movement creates a lower pressure in the crankcase, enabling the mixture to pass in from the carb. <br /><br />when crankcase seals or gaskets fail, the crankcase cant hold pressure anymore. Another source of leakage, such as base gaskets, or a cracked casting will yeild the same results

<br /><br />I remember my teacher telling me this about 3 years ago after i read this post. Thought i would relay it, not too sure how much it helps, but i hope you get this resolved without having to tear into it too much. Like i mentioned though, You should still feel vacuum whether or not your fuel pump is out. Only other explanation I can give is the same one laddies mentioned, and that is reed valves and or you just had a "mind slip" and left the throttle closed when you were checking for vacuum <br /><br />Good luck !
