Good news is it starts every time I turn the key, without aid of the accelerator, but it will only run for 5-10 seconds before it dies. If I press accelerator down it will rev then drop and almost die, then gain revs again then die. Quite a bit of smoke coming from carb/intake pipe after trying to rev, not when left to idle, or very little. Still bad timing? or do I need to adjust carb? ( I'm new to carbs, not sure which screws which)