After 2.5 years, my KFX50 (GY6 139QMB engine) developed some hard starting issues and supposedly that was a symptom of poor valve clearance.

I aligned the index mark to the T mark on the flywheel per the service manual and popped open the valve cover. There was no clearance between the tappet and valve, so I adjusted it until my .04mm feeler gauge would slide with some resistance between the two.

Put everything back together and now I think the ATV is louder in general as well as having a louder ticking sound. On the flip side, it starts instantly. Is that normal?
I can't recall if the sound was there when the KFX50 was new and went away as the valve clearance went out of spec...

Cold start.

Warmed up.

 

I would double check that valve clearance, making sure you are at TDC on the compression stroke when you do it.

 

Hey merryman, thanks for replying to almost all of my threads... really appreciate it!

I took the valve cover off and rotated the flywheel until the index mark was aligned with the T mark AND the main hole was centered between the valves/tappets... Wow, the rocker arms were wobbling and that's what was causing the noise!

Decided to adjust the valve clearance by rotating the flywheel clockwise until the exhaust valve was all the way depressed and set the clearance on the intake valve to .04mm. Then rotated the flywheel clockwise until the intake valve was all the way depressed and set the clearance on the exhaust valve to .04mm.

Double-checked the clearance again by aligning the marks and hole. Looked good.

The KFX50 still starts immediately and sounds correctly now! Also feels like it has more torque.