"Is it the horrible Zama carb with only 1 needle?"

No - It the horrible one with 2 needles - H and L. The engines starts O/K (magneto - not CDI) with a finger over the velocity stack to prime and pop then a good run with an electric starter, but it only has one speed - full steam ahead. Adjusting the low end does nothing. We have had all the "experts" milling around offering advice and the general consensis is - change the carb. It seems by everybodys advice and experience that the Zama tends to be probmatic - if it goes, great - if it doesnt, replace. I'm reluctant to have money / time spent on it when after it's all added up a new CDI engine may be cheaper. I don't have the walbro spacer - just the carb that was given to us as a freeby to try - hense my reason to just bolt on the walbro direct to the head.