GY6 150CC Sparks Strong, Then Stops

[Aggie_Grad_12]

I have a Chinese scooter that is having some serious spark issues. It's got 600 miles on it and the carb was clean as a whistle when I got it. I put in a new battery from a different 150CC and it started immediately. Idled like a dream and ran up to 50 mph no problem. Then out of nowhere it shut off. I walked it home and started looking for plugs in the fuel line thinking the bulb had emptied and not refilled. About 4 hours later the scooter started and ran fine. I thought I had fixed the fuel problem so I got on to ride, a mile later it shut off. It did this about 3 times before I finally pulled the plug and realized it wasn't sparking. If I run it till it stops and let it sit over night it usually will spark in the morning. I'm having a hard time diagnosing it because sometimes it works and other times it doesn't. Has anyone had this issue before? I don't know if the battery is the right one for it but the scooter turns over strong it just won't spark. I'm planning to pull the stator this weekend to check it out but I would really like to avoid that if it could be something else. The CDI and coil from my other 150CC don't fit it so to check those I would have to buy new ones.

[kz1000st]

Have the valves been adjusted? Seriously. I mean you could have a bad coil or CDI but the first place you start with Chinese scooters is the valves.

[Aggie_Grad_12]

They have not but there is no way those could be the issue could it? The scooter works for a few minutes, then shuts off for a few hours, then works again. Plus the valves don't affect sparking at all. I would think it was heat related except yesterday I idled it for about 30 seconds before I hopped on to ride and it shut off immediately.

Is it possible there is a shorted wire somewhere that is grounding out the spark? The thing that gets me is when it stops working, I'll pull the plug and check it, no spark. Then every time I walk past it I turn the key, ground the plug, and hit the starter until I see a spark. Usually it takes 4-6 hours for the spark to return but I have literally not moved the bike an inch so a shorted wire shouldn't cause it. This pattern has been very consistent for about 4-6 cycles.

[Maddog]

do you have a side stand on that model? If the switch goes bad it will kill the engine, like it does when you lower it with the engine running. Remove the switch and " open the circuit". If your problem goes away replace the switch or repair the wire.