My engine runs great, startsup perfect and couldn't idle any smoother. But what boggles me is it runs like an HT, vibrating, rattling and so-on. But there has been quite a few times where it will smooth out having almost no vibration, have an enormous amount of power and run smooth as silk, why it does this I don't know, it's not 4stroking and that I'm certain. I'm not sure but maybe it's from a weak CDI or sparkplug and all the sudden it gets the right amount of juice? I changed the cable after being worn out and abused after 2 years and my plug is fairly new but it still does the same thing. Any ideas? Am I running rich, is it a weak spark?