Is a good plan to have a spare engine on hand if your depending on your bike to get to work. Just a thought, I would try and get one from where you got your kit for "swap-ability" of parts. A good many dealers sell just the engine. I did a quick search and found this; motor motorized gas engine bike REPLACE 66cc engine new on eBay!
Also could check swap shop section and fellow MBers near you. Cool part of our crazy lil world, folks love to help ya out.
Did I ever tell you Thine, I used to live on Fair st in your fair city? Then moved to Palenvile.