I have a 03 honda 250ex, i was running almost full throttle, it suddenly lost power and was acting like it ran out of gas i turned it to reseve but it didnt help, it came to a stop and stalled, it had half a tank of gas, so i checked the oil, it was really low so i added less than a quart and it was at the right level, i put a new spark plug in it, gas is getting to the carburetor, it's getting a good spark, but it just will not start, I have cleaned the carb and jets to the best of my ability, it ran perfect till now, I have racked my brain to figure this out! Anyone know why it won't start

 

Does engine still have compression? Do you mean starter turns over engine but engine wont start or starter wont start?

 

The engine seems to have good compression, the starter works and turns the engine but the engine won't start

 

Bump

 

If you are CERTAIN you are getting good spark out of the spark plug electrode, AND it has good compression, then it has to be a fuel problem. Take the air breather off and squirt some WD40 into the carb while you are turning the engine over and holding the throttle partially open.

 

I've squirted a little bit of fresh gas in the carb but it still didn't do anything, I'm going to check the plug again to make sure iv got good spark

 

The reason I suggested a spray can of WD-40 was because it is under pressure. And, while you are turning the engine over, the vacuum will suck in the WD-40. It does work great as a starter fluid. Just thought it would be easier than trying to prime it with gasoline.

 

Ok I'm willing to try it at this point

 

Been tinkering all day with it, still not running. How much compression should this engine have?

 

Prolly 85 to 110 pounds