Need help with a 150cc. Cleaned Carb, replaced autochoke and sparkplug. The engine will turnover good but will not crank. The last time it was running the engine sounded rough and was sputtering as if there was something wrong with the Carb. Could it be the timmimg or compression?

Thanks,
Steve

 

Do you have spark?

While the plug is out, hold your thumb over the spark plug hole and press down hard. Crank the engine. The compression should push your thumb off no matter how hard to push back. (This is a poor substitute for a real compression test, but it is easy to do...)

Pour 1/2 teaspoon of gas into the cylinder through the spark plug hole. Quickly put the plug back in and crank. Any signs of the engine firing?

 

Very little compression. I can hold my thump down without it coming off.
Now what?

Steve

 

Do a valve adjustment. If that doesent work you might need rings. Your comp shuld probly be around 100 psi.