I have a 2003 honda 400ex and it sputters and wont go any faster at full throttle i changed spark plug and i just sprayed carb cleaner in carb i just need to put back together to see if that works i was just wondering if it could be anything else.

Thanks,
Luke

 

you sure you are not hitting the rev limiter

 

Check the petcock coming out of the tank. It works like the old settling bulbs and could be full of water or the screen stopped up. Also take a look at the air filter.

 

if low and mid throttle is ok i would check the main jet for clogging or debris. if you have re jetted it i would confirm you have the right size main jet in. maybe make sure the air filter is clean and sending enough air to the motor. sounds like an issue of too lean or rich gas mixture. check the gap on the plug with your owners manual too. if the plug is white or scorched looking then you are too lean. if it has alot of black soot on it yhen you are too rich. or you may have bad or old gas.

 

Make sure the choke isn't on...

 

the choke wasn't on i got it fixed it was either the carb was clogged or the filter was clogged because i cleaned both and went up and down the street and it works great now thanks to everyone who gave me an idea.