Has anybody also encountered a problem with the stock plug? Here is what happened with my motor: Out of the box it started up, but very hesitantly. It would run for a few seconds and then quit. This continued on until the engine would eventually warm up. After a while she would continue to run. I suspected the plug for being the culprit. Every time the motor was cold it would do the same thing; briefly run and then quit. So I bought a new plug and replaced the Chinese junk. Now it runs like a champ. Right from a cold start. No quitting anymore. So far I like this engine. Very little vibration, very low idle and plenty of power. We'll see how long she'll stay in service.