hey there got a 1980 citation 4500 with what i belive is a 1979-1983 ski-doo 377 twin carb, premix engine with points. does anyone know how to time these engines and the problem i have is that it runs rele good cold, occationaly runs on one cylinder then after 3 mins of hard riding it just dies out. new plugs rarley fix the problem. mix is done at 40-1 and both plugs have spark. so whats wrong????? snows not gonna be here for long lol.