So what your saying is it lines up at 180 deg but not at 0 deg rotation OR? Sounds like you might be off by one tooth at the crank.
Pictures may help.
In general: rotate the cam till the valves are closed, rotate the crank till the piston is at bdc or tdc (whichever the markings are set for). check the markings, adjust position if necessary. bolt on the cam sprocket with chain installed.
test rotate the crank by hand to make sure nothing is amiss. do it again with electric start.
if everything feels and sounds ok install the spark plug and start it. make sure your hand is on the kill switch. kill the engine immediately if you hear anything weird/noisy/abnormal.
If all is good:
warm it up, readjust the valves if necessary. check the spark plug, tune carburetor as necessary.
Hugh
SDscooters
Pictures may help.
In general: rotate the cam till the valves are closed, rotate the crank till the piston is at bdc or tdc (whichever the markings are set for). check the markings, adjust position if necessary. bolt on the cam sprocket with chain installed.
test rotate the crank by hand to make sure nothing is amiss. do it again with electric start.
if everything feels and sounds ok install the spark plug and start it. make sure your hand is on the kill switch. kill the engine immediately if you hear anything weird/noisy/abnormal.
If all is good:
warm it up, readjust the valves if necessary. check the spark plug, tune carburetor as necessary.
Hugh
SDscooters