Rub some dirt on it
OK I have a 99 rm 250 which i just got abnout a week ago. It ran fine the other day then for some reason when i started it today it was shooting clouds of smoke i thought maybe it is just cold I rode it around for a while and seems to be under powered. so i gave a quick assumtion maybe i should run different oil. I went out and bought full synthetic oil and mixed 40:1 and it hasn't stopped smoking. so I took the motor apart and noticed one of the rubber O-Rings was outta place. So now I am thinking it may be leaking coolant into the cylinder I am waiting for them to come in so i can find out if that is what it was. O and the piston is clean and the top dommed part is clean to no carbon... If anyone has any Idea of what it could be Please help...