my 400 wont start

[pauls427]

just got the top end rebuilt put it all back togather and it wont start all it does is fire and sometimes back fire.please help

[toby400ex]

Check your timing, sounds like its 180 degrees out of time.

[pauls427]

i checked the timing its dead on i bought it used with a bunch of motor work done would this problem be if it has an advanced timing key in it.

[Atreyu]

I'm having the exact same problem. I just had my motor redone too. Any help would be GREAT.

[red03400]

this might sound stupid but it happened to me thats the only reason why ime saying it.... check the gap between the sparkplug... it might have gotten droped or tapped outa place...use a feler gauge..idk wat it is supost to be at.....and if that doesnt work check your float it might be jamed up in the carb.. that also happened to me :rolleyes:

[cals400ex]

popping thru the carb may just be from lean condition on the pilot jet/fuel skrew.

[foleyit]

Originally posted by toby400ex
Check your timing, sounds like its 180 degrees out of time.

I had the same problem, and it ended up being 180 out.