I just bought a 1986 yamaha ty250 and this is my first time riding a trial bike, in my experience with many 2-stroke bikes, I find them very strong at the initial throttle, easy to wheelie, but on the ty250 i just bought, in 1st 2nd 3rd gear it is not strong, it just keeps slow speed, can't even do a wheelie, is that normal or is there something wrong with my bike?