The Mobile Cycle Shop

I recently bought a 1992 Honda Nighthawk 750 from Mike, the proprietor of the Mobile Cycle Shop, who advertised the bike on Craigslist. Mike initially seemed very helpful, for example, he trailered the motorcycle from his location an hour away over to my house in Chapel Hill so I could look it over and do a test ride. Mike explained that he was a motorcycle mechanic with a mobile shop, so I didn’t think it was necessary to take the vehicle to an independent shop for an assessment. Besides, the bike looked very clean, had low mileage, started right up and rode well.
That is, it rode well for about 20 miles. A couple of days after I bought the bike, I took it on the Interstate. Shortly after hitting cruising speed, the bike began to lose power. I pulled it to the side of the highway where it stalled out and wouldn’t restart. I tried calling Mike to see if he had any insights into the problem, but he didn’t pick up. I had to spend $ 85 to tow the bike back to my house in Chapel Hill. So far, Mike still isn’t picking up his calls to offer any guidance or explanations for what could be wrong.
I paid $ 1600 for the motorcycle, and accepted it in «as is» condition. But I thought it would carry me more than 20 miles before breaking down and needing a tow. I’ll probably need another tow to get it to a competent mechanic.
There are two possibilities. 1) Mike sold me a motorcycle that he knew was junk, or 2) Despite working on the bike, he just couldn’t get it into condition where it could be reliably ridden, and didn’t recognize the problems with the vehicle.
Either way, I lost big in this transaction.