I have a 2003 Yamaha Beartracker 250. I decided I'd ride it down to a friend's house a couple miles down the road. I had done it before so I didn't think I was taking any risks. As I was headed down the road in 5th gear, I usually don't push the throttle all the way down, but with a car coming behind me, I had to push it down all the way in 5th gear for 3 or 4 seconds. All the sudden I lost all power and stalled into a driveway. The battery was completely dead so I charged it up for 15 minutes and it was good to go as could be. When I try to start it, it will turn over and over but there's no combustion. The spark is good, I cleaned the carburetor without disassembling it, it has a new intake manifold. I've tried spraying carb spray into the carburetor and air filter. No results. Any suggestions? I've tried researching the problem since and have found nothing. Any help would be much appreciated. I've been trying to figure this out for at least 3 weeks.

 

Has to have compression,spark,fuel and air to run.You say it has spark,then I'd check compression before you go too far and check the valve clearance.If you haven't changed the spark plug it may be as simple as a partially fouled plug. And yes that can happen on a 2 stroke and a four stroke. If it won't even try to kick over with starting fluid then something's wrong somewhere.