Can valve clearances be adjusted to liking or do they have to be set to a manufacturers oem?

I've got a 125cc and It feels like the valves are slightly advanced however this is factory and it's nearly new.. was wondering if I could adjust them to my liking or based on another 125cc engine I like??

don r

Don't go trying to advance or retard the valve timing and that has nothing to do with adjusting valve clearances, which has on correct measure- OEM. My crystal ball shows you crying beside a dead engine with bent valves that won't run. You keep asking about this every day and people tell you over and over to leave the engine alone.


You know nothing about engines. Leave it alone. Valve clearances are not "advanced". That is the ignition timing. What exactly is "your liking"?


Valve lash must be set to factory specs. Too tight and the valves will not shut properly and will eventually burn. Too loose and they will not open enough and be noisy.


READ the manual. The valve clearances are SET by the manufacturer. Valves clearances are NOT advanced. They are either up to specs, tight or loose.


Here we go again. You have no clue, slick. But hey, you go ahead and adjust and please post the results.


Dude you have no clue what you are doing. Just ride the damn thing. If the valves are opening too soon you'd have a cam timing problem, not a valve clearance problem. You'd also get backfiring out the intake manifold. You have a slow 125cc motor.Be glad it runs!


Camshaft design requires the proper valve "lash". Valve "timing" and valve "clearance" are not the same.

Tim D

Yeah, just base it on an another engine you like – what is the worst that could happen?


Only on a personal whim if your desire is to burn a valve or run a valve threw the top of a piston.... or poor performance somewhere in between the two.

Justin Thyme

They need to be set to the proper spec.


Many engines have no valve adjustment, especially if the lifters are hydraulic. If the scooter is that new and there is no manual adjustment, don't mess with it or you'll void the warranty.