Just picked up a RT 180 last week, bike runs real strong at first but after about 20 minutes of hard riding it starts to bog down while on the throttle and smoke excessively. I am a total novice when it comes to 2 strokes but here's what I know, the bike was originally oil injected but the PO didn't "trust it" so he has always mixed the gas. It started acting funny yesterday so I changed the plug this morning and filled the tank with 93 octane (ethanol) and the bike ran great. Then after about 20 minutes or so the same thing happened, excessive smoke and bogging down while on the throttle heavy. I am totally green when it comes to these bikes so I guess I need a little schooling. Is it possible I'm just running it too hard too long?a guy at work told me that sometimes there was packing in the exhaust that sometimes needs to be changed? Thanks for any input.