High revving 8 valve engine needs to be caned to get anywhere quick but chassis works well with so little mass. Engine tough but continuous thrashing and high miles causes piston, small-end and valves to wear out. Not the kind of engine on which to miss oil changes nor neglect maintenance. Poor finish and shagged suspension should be expected at this age. It was quite easy to lose the front end on slippery roads so check the frame and forks for signs of crash damage.