troubleshoot motor

hey I been reading this forum for a while and can’t find a solution so decided to make a post. I bought a used 66cc bike off someone it’s broken in beautifully and it was running amazing. I use it for work as a courier and I only rode it for one day about 6 hours. I sat down to smoke a cig and...

Ok so, this is my 1st ground up build( Building rear Rack, using parts of a Kit...Motor/gear reduction/throttle kill switch, building mainly with some scraps/mechanisms I picked up for free, minimal hardware from Lowes)& I have very limited space but it's coming along nicely. Rack is done other...