What gear are you trying to start it in? I recommend 3rd or 4th gear as that has always worked with our 3wheeler. Otherwise try getting a new battery (if electric start). Some of those old 3wheelers can get tricky to start. You can try putting new gas in or some dry gas that will get any moisture out of the fuel system if it has been sitting awhile. A few other things of basic maintenance would be new spark plug, spray out the carb. with carb cleaner. Hope that helps.
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