starting problem

[04yfz450nj]

my buddy has a 04 yfz that we can only start if its jump started if u shut it off it wont start again in less ya jump it.

[lonnie1977]

Check your valves.

[BakerRacing40]

check your grounds, take the cables off the battery and clean up the terminals and cable ends and hardware ( even if they look clean, they may not be, at least use a wire brush. ) , if no luck i'd be looking at the battery...