1984 yamaha 125 tri moto issues

[jdhallmark1994]

got a 1984 Yamaha 125 tri moto from a buddy, he said it needs piston and rings replaced. i took the top head off and piston moves good, cylinder is not scratched or anything, looks good and feels smooth,i took the bottom 4 nuts off the studs holding down bottom cylinder and was not able to take bottom cylinder off, is that all holding bottom cylinder down??? i put it all back together and pulled the pull rope and it started first pull. idled really high,and blew out a lot of white smoke. if i could describe it it was screaming. so i killed it and took carb off figured it was stuck, and it was. the slide cylinder was inserted wrong. i cleaned carb, put it back together and put it back on, and now i cant get it to start. any ideas on what i should start with? asked previous owners what problems they had with it and they said same as what it did to me and that they just didn't have time to mess with it.



also, can i upgrade the motor? make it to 175 or anything like that? and where is good place to order parts?