I got an ar80 from dougler over the summer, and have been riding the hell out of it. The timing slipped at one point (flywheel completely came off the crankshaft) due to the kickstart being broken and having to bump start it. After i fixed this (incorrectly), it ran beautifully and would do 60mph no problem.
Last weekend i took it to bombourbon run and on the way back i blew a hole in my piston due to the timing being too advanced:
So i bought a 93cc kit for it from here expensive as hell, but parts for these are super rare and shipping from the UK was more than the kit itself. it arrived within a week and they sent me an extra piston, and gasket set along with a note that said they sent an extra one because they value their overseas customers. Rad dudes for sure.
I removed the old cylinder and cleaned out the crankcase of piston debris. I installed the new piston and cylinder but broke a ring in the process. Fortunately they sent that extra piston and i was able to use one of the other rings they sent me and was able to install the new kit successfully.
I removed the old airbox, tacho and speedo (they also broke on bombourbon) and i plan on building a mount for my gps unit where the instrumentation previously was housed. I also need to get a K&N style air filter, new jets, and some more plugs. And last but not least i need to fix the timing correctly so that i dont blow a hole in another piston. With the added torque and power from 13cc's i'm going to probably get a bigger front sprocket going from a 14 to a 16 tooth and perhaps a smaller rear if i think its necessary. i'm hoping to be able to do a comfortable 70mph cruising.
Thought i'd share. come check it out next time you're in cincinnati.