if it's been maintained, yup, it's worth it, if it's a country boys bike that never raced it, i'd walk away, if you can, put it on a stand so at least 1 tire is off the ground, start off looking for obvious oil leaks, (countershaft seal, fork seals are most typical) then rock the bike back so the front tire is off the ground, try to feel for play in the fork tube, rock the front wheel forwards & backward, try to feel for play in the fork tube, not the steering stem, if there is, it will need slide & glide bushings, fork seals & fork fluid, then check for the steering stem, they are tapered bearings so it will need a bit more force to show if they are worn (you don't need to be shaking the bike off the stand though) check wheel bearings, side to side, spokes for bent or loose, wheel for trueness, side to side & up & down, watch the lip of the rim, not the tire, use a pencil for a pointer if needed, move to the back of the bike, rear tire off the ground, do the same to the wheel, then grab the wheel, move side to side & watch the swingarm pivot pin for movement, then leaning over rear fender pull wheel straight up, feel for a clunking, if there is, watch for an upper or lower shock bearing (most commonly missed bearings for maintenance) if it's not that look @ the linkage, run compression test, pull clutch lever, see if it feels gritty or like it's pulling past saw tooth edges, take it for a ride & feel the mechanical function, clean or rough, clutch slippage, if there is make sure the cable isn't too tight, also see if the shifter & brake pedals are floppy, a lot of rookies jump & land on them, no biggie for the brake, new bushing (if it's serviceable) & go, but the shifter can cause unneeded issues with the shift drum & forks, i'm bored of typing now, later