Sounds like valves to me mate, might be wrong like. Get the clearances checked but do it when the engine is stone cold. Easy enough to do on that
+1 on the valve clearances. iirc they are nut & screw so will be easy to do. you want about 6 thou inlet 8 thou exhaust, but check in the manual... theres a free pdf manual in the downloads bit. same engine as the en / gn / gs 125... the engine is bulletproof so it's unlikely to be anything serious. *the only manual i can find is in german lol but quotes the valve clearances as Valve clearance (intake):KALT 0,13-0,19 MM Valve clearance (exhaust):KALT 0,19-0,25 MM which in english (imperial) is (COLD) intake 5 thou to 7 thou exhaust 7 thou to 10 thou, so the original guess wasnt far out lol. and it is nut & screw adjustment so no fking about with shims.
what?? to check the clearances??? yeh, just remove the tank (you might not need to tbh) remove the cam / rocker cover on top of the engine.... clean it before you remove it to avoid crap getting in the engine. you can see the valve clearance adjustment screw & locknut . remove the timing cover so you can see the timing marks on the flywheel. turn it over to the T mark lines up with the mark on the left side of the crank case.... check you can wiggle the rockers and feel a very slight gap... if there is no gap, turn the engine over 360 degrees and try again. the lobe of the cam should be pointing sort of diagonal and not pressing upwards against the rocker, pushing the valve down. use a clean feeler of the right size according to the spec of the engine... you should be able to slide it between the valve & rocker and feel very slight resistance, ie not loose or grabby. make adjustments accordingly. if you are not at all confident doing this, you need to stop & ask for help. yours is a very easy engine to learn maintenance on and will be hard to fk up
Oh ! I was hoping it was going to be easier than that lol !! Am not that confident about removing the rocker cover and mucking about inside !! Might have to see if I can transport it to a garage !!
IT IS EASY it'll only be held on with a few nuts then it will lift straight off. should be dead easy to get at on your bike. just make sure you line up the T mark, then see if you can feel a clearance, if not, as said above, turn the engine over by hand a full turn until the T mark lines up again. then check / set the clearances - done. if you're totally stuck, fetch it round here but bring your feeler gauges cos i havent a clue where mine have gone lol! i'm off for 2 weeks so anytime when it's light, preferable when it's not pissin down cos my garage is rammed with partly disassembled bikes lol
