"Alan,
The stator, which su
"Alan,
The stator, which supplies electricity for the ignition, has two windings. One winding is for low rpms, and the other is for high rpms. If the high speed winding is not working properly, it can be tough to diagnose. The spark will appear to be good, especially at cranking speed, but the engine will not rev above 1500-2000 rpms.
I guess you have already checked the wires to the switchbox, but if you haven't, you should make sure the wires are connected properly. The terminals on the switchbox are labeled with the color of the wire that should be attatched to them.
It could also be a reed valve, as you mentioned. You can perform the test I told you about, but you can also make a more positive observation if you want to. If you remove the carbs, you will be able to see the collars that fit around the crankshaft. These collars hold the reed valves. It is possible to use a probe, such as a length of stiff wire, which you can insert through the intake flanges, and feel if the individual reeds are broken or not. This requires some patience and time, but it can be done. A bright flashlight will help. You have to bend the wire differently for each reed, so that you can reach in and press on the reed to see if it is there.
It helps to look at these valves on a parts diagrahm, so you can see exactly how they are positioned.
One other thing I would mention is to turn the flywheel in a clockwise direction by hand and see if you notice any difference in the resistance that you feel as each cylinder develops compression. If you feel no resistance for one or more cylinders, you probably need rings and or a piston. Sometimes, even though the compression test seems good, the rings or pistons are worn. This test is useful when that is the case.
There are a number of conditions that can cause this to happen. If there is a lot of carbon built up, the rings can be frozen and worn, but the carbon causes the compression to read high.
If the rings and or pistons are just worn a little bit, they might hold compression, but will not produce enough vacuum.
Tony"