non starting wisconsin ae

hi. i have got my engine to starting point. there is a good spark at the plug and carb jets are clear. i have been turning it over and over for a week and it has only run twice and each time it has run supberbly. no noise good control on the regulator. once stopped back to no starting. i have checked timing and carburation are all to the book and there is plenty of compression. any ideas before my shoulder gives up.

How good is the spark? Is it bright blue and can you hear it click?
Sometimes what looks like a healthy enough spark will fail when under compression. Also, what spark plug are you using? Modern ones which have no glazing on the lower parts of the insulator can give this sort of trouble.

You say that there is plenty of compression but have you actually measured it at the plug? Any blow past the rings will cause poor starting. Sometimes, the fuel can seal the rings and then it runs good. You could try pouring some neat fuel (or oil) into the cylinder, replace the plug, and see if it starts any better. Failing that, as Ian says, you need to check the spark and/or the plug.

You have to remeber it's an old engine with plenty of wear on things like timing gears, so setting it to the book is for a new engine in good condition so you may have to mess about a bit with the timing to get it correct and take out the eliment of wear to get it to run better. Hope these hints are helpful if not come back and we'll have another head scratch and see what else we can think of.

Stu.