400EX Won't Stay Running
 

I just recently rebuilt the engine top end. And I'm having trouble keeping it running. I tore down the carb and cleaned it yesterday and reinstalled it today. Fired it up and it ran for maybe a minute and half then died.

Could the plug not be hot enough?

Could the timing be off a little bit?

Any suggestions would be great.

Thanks,

Brian

400EX Won't Stay Running
 

Timing, valve adjustment, cam, rings, piston,,,,, could be any number of things.
I'd say it's time to take the top end off again and have a look.
I dought it's the spark plug.

400EX Won't Stay Running
 

how is it dieing? runnig out of gas...just cuts out..or something els? are you using any choke?

400EX Won't Stay Running
 

<div class="FTQUOTE"><begin quote>Originally posted by: Red400EXRod

Timing, valve adjustment, cam, rings, piston,,,,, could be any number of things.

I'd say it's time to take the top end off again and have a look.

I dought it's the spark plug.</end quote></div>

I re-adjusted the valves yesterday and had it running for a good 3-4 minutes at idle and high RPM. Then it died out again. May need to make some more adjustments to the vlaves and possibly the pilot valve.

400EX Won't Stay Running
 

Runs and then dies,,,, sounds like a fuel starvation problem.
How long do you have to wait until it will start again?

400EX Won't Stay Running
 

<div class="FTQUOTE"><begin quote>Originally posted by: Red400EXRod

How long do you have to wait until it will start again?</end quote></div>


Several minutes and then it will start up.

400EX Won't Stay Running
 

Definately sounds like fuel starvation.

400EX Won't Stay Running
 

Sounds like the bowl is not filling up since it runs for a few minutes then when it dies takes a while before it'll start back up. Make sure your float is working properly.

400EX Won't Stay Running
 

agreeded, float problem. pull it apart and clean. also the fuel line from the tank and make sure there is no trash in it