The Lifan 200 seems to be a well designed and decent quality engine. I also had a 2007 Lifan LF200GY-5 dual sport bike, unfortunately it did not last long. Just past 3500 miles, that centrifugal oil filter came loose from the crankshaft and destroyed the engine. I was way out in the desert at the time, fortunately within cell phone service range. The filter was installed with just a nut, no lock washer, or any sign of thread locker. The nut just came loose. If it hadn't been for that, it may very well have lasted a very long time, as I over maintained it. Maybe someone at the factory just forgot to put locktite on it, but I would have used either a Nyloc nut, or a a flat washer that could be bent around the nut, like is used on many clutch nuts. One thing I really liked about that engine was the pushrod OHV design. I am not a fan of non replaceable internal cam chains. It does look like the oil pump is chain driven, but you can get to it. With that many miles on it, I'd replace that chain.
I won't spend more on a bike than I think it's worth, but if it's a good deal, I don't seem to have a problem buying bikes I don't need.
2002 Vulcan 750, 2013 Royal Enfield B5
2001 XT225, 2009 Genuine Stella
1980 Puch moped