Howdy all...struggling to fix one of these Chinese beasts that a friend purchased for his son. The symptoms are a rough idle and the 4 wheeler wants to stall when giving it any throttle. It will start right up and idle, but it’s rough enough to shake the 4 wheeler. I’m pretty handy in regards to carb work, so that was the first thing I attacked. I cleaned it good, but got the same results. As cheap as the carbs are...I thought maybe something was out of spec on the inside, so I purchased a new one. Same symptoms. I set the valve clearance, checked for leaks around the carb and replaced the plug with the correct gap. Symptoms still the same. Compression also checked ok. Once the 4 wheeler warms up...it will stall occasionally while idling, but immediately starts back up. I initially thought that the coil was going bad causing it to lose spark once it heated up, but I used another plug to test for spark when it stalls and it still has a nice pretty blue spark. One other thing worth mentioning...it seems like the 4 wheeler is running hot. At this point...I feel like it’s an electrical issue, but for the life of me I can’t get it figured out. Any help would be appreciated!!

 

Like you wrote, it starts back up right away so the fault isn't a binary works or doesn't, so the coil or CDI could be the problem. Not often I recommend substitution but, in this case, I would try one or the other. Also possible it is the stator or trigger coil. I would check valve timing before buying any new bits, but I suspect you are going to have to.

 

Thanks for the advice!! I have parts ordered...guess I’ll find out soon enough if they work. I’ll post my findings. Thanks again!!