I have an 03 I bought in '06. Had two previous owners, I have went through two back tires and two chains since I have had it. It was in really good condition with stock graphics and still really clean. I am debating on rebuilding the engine. Before I spend a huge chunk of change...do I need to? Estimating engine hours is hard, but I would guess maybe 100 hrs? Prolly less. I am not a racer, but I enjoy hauling tail when I do get the chance to ride. I ride maybe a dozen, two dozen weekends a year. Some sand dunes, mostly trails and the occasional practice day with my little brothers. From searching and reading posts it seems they hold up pretty good..some guys loggin in tons of hours on these engines. I know a timing chain for sure...but piston? rings? valves? Is worth to go through and spend several hundred on new everything? Or is it overkill to replace parts that still have life left? Im just looking for opinions.