Motor problems on a 99 blaster.?

i was running my blaster down the road when it sounded like it blew up, i lost power and speed. it was still running so i rode it home. it was spitting and sputtering every now and then, but it ran bout 30 mph in 6th gear. i was riding it all week, mudding, trails, ect. there was a little dirt on the reeds but the piston and rings and every thing up top looks fine. u have plenty of oil and gas getting to it and i also cleaned out the carb. what else could it be? have any more questions to ask me, go for it.