Post by davescootissues on Jul 21, 2015 1:11:48 GMT -6
Hello-
I hope I am posting in the right section.
I recently have purchased a 44mm crank, because the threads on my old crank were bad. I have rebuilt 4 different 139qmb's and am wondering if I might have done something wrong, while installing the 44mm crank and 47mm big bore rebuild kit. It has 69mm valves and the correct rocker arms. I have set the valve lash at .004. I am having trouble getting it started and I know the carburetor is good, but that isn't even what I'm concerned about. I usually turn the motor a few dozen times by hand to help spread the oil around the new engine. This time I am hearing a snapping noise at 180 degrees from TDC when I slowly turn the motor. It almost sounds like a valve problem, but I can't figure out why that would happen. I have 4 base gaskets to make up the space difference from the previous 39mm crank to the new 44mm crank. The noise makes me afraid if I do get the engine started it will just be ruined.
Please let me know if anyone has an idea of what may be wrong.
Thank You