i have an 85 Lt 250r it's bored .040 over and not sure if its ported or not. it has a fmf pipe and silencer. i jetted it for the pipe like a month ago. just like 3 weeks ago it started to bog from half to full throttle. i raised the needle because it feels like it's starving for fuel. but that didn't help, it's not running lean becauce the plug reads tan, i mix the fuel 93 octane with yamalube at 32:1. i need help badly, do i need to replace the rings? all help is greatly apperciated. thankx

 

sounds like it is starving for air........