a hells satans responding - nothing much to add to Eldon's post except to pull your plug and check spark and to verify that the plug is wet (with gas) if spark is good. If you are getting spark and gas to the cylinder then it's time to start looking at the top end of the engine.
It is easy to foul a plug in a two stroke engine. Anytime I make a change to my carb or engine I'll foul a couple of plugs getting it right. You should replace it with a NGK B6HS (although a B5 or a B7 or champion equivelent will work) and keep the gap low.
I'm no expert on Motobecanes, but anyone will tell you I am the Garelli expert around here. A few of us rent space in a warehouse past the Lion Mart on Chamberlayne north of US 95. Any of us would be happy to help and Lee can fix anything for loot.