So we bought this quad used for the kids. Ran on, had to use the choke to ride. So I pulled the carb off and cleaned it real good. Put it back on, and it started right up, then died. Then would just turn over and over. It didn't sound right when turning over. I could feel exhaust coming out. So I pulled the spark plug, could see the piston moving. Checked spark, it was good. Checked compression and nothing. So I checked to make sure the rockets were loose. They were. I shined a flashlight into spark plug hole and cycled the motor by hand while looking in the exhaust port. Well the light never would go away when the valve closed. So I pulled head and position looked good, cylinder bore looked good. But neither valves are seating. I could tap them and they would, but if I bumped the rockers they wouldn't seat back down. I was gonna order a new head, but I'm having a hard time locating one or the correct one. I have found a few and I'm not sure what the bore is on mine. The motor is marked 124cc, it's stamped 1P52FMI. Any help would be appreciated.

 

There is nothing wrong with the cylinder head. Stuck valves can be caused by a number of things, remove them and clean the carbon off. It is a bit suspicious that both are sticking, are you sure you haven't had the timing wrong? If the valves touched the piston they will have bent and will stick, you will then need new valves, you can see if they are bent when you turn them round. Coat the stems with grease when you re-fit them.

If it says it is a 124cc, it is 124cc, that E22 clone engine is rarely made in the 125 size range, so get genuine Coolster parts.

 

When I go to coolsters site under my atv model the replacement head is labeled 120cc. And for the timing I'm not sure, I didn't mess with timing, only pulled carb off to clean. With the head off I can shine a light into the combustion chamber and see light through the valves while looking down the intake and exhaust port. While rockers are loose. If I lightly tap the valves they will close, but if I lightly tap the rocker they return to the barely open. Sounds as if they could be bent, and if they are not sure how it happened. Unless the chain for whatever reason hopped.

 

if the valves were out of adjustment then they will contact the piston as well. If you loosened the rockers then the valves are now out of adjustment and will not close or open properly. While you have it apart pull the valves clean and check for being bent. Then put them back in and adjust according to spec. I would almost bet the valves were out of adjustment when you fired the first time and you slightly bent them when it started

 

Ya that's the plan, not sure how it happened. Ran this past weekend without issues. And I haven't touch valve adjustment. When I noticed neither valves weren't seating and the valves weren't keeping them open I new I had to just pull the head.