Fuel spilling from drain tube.

[JDMThoughts]

After redoing the carb on my friends bike to get it back up and running nice again. The bike runs, and starts fine, but if the bike is started and sits and idles it spews some fuel out the bottom. We don't know what the problem of it is? Everything else on the bike is fine, except this one problem? Any ideas? I appreciate any knowledge that is spread on the issue at hand.

[JParisi48]

?!?!?1 mine does the same thing when i do wheelies but i thought it was normal, yea please someone tell us what causes this?!

[dirtdawg]

this is because your float height is too high it is flooding over. make sure the drain crew is seated properly. if not, get a carb rebuild kit and make sure to lube the needle valve. that is what happened to someone's 400ex and my blaster, when i had it. simple fix. most likely the float is sticking.

[JDMThoughts]

How do you go about adjusting the float, this is the first time I have ever had this problem before, when I did carb work. So this is new to me... I don't have a manual right at my fingertips to do it either.

[dirtdawg]

i don't either. the 300 float isn't adjustable, so you need the new needle valve that is attached to the float. i brought the blaster's carb to a shop.

[Grimzella]

JParisi48, I have seen other 300ex's leak when riding wheelies so i'm not sure if this is normal.. it prob is normal considering the quad is not in normal position. not sure.

[dirtdawg]

if it is doing it in a position parallel to the ground, it is abnormal. the 300ex float level IS NOT adjustable. in the manual, it says that a new one is needed to achieve the specified height.

[JohnT_98300EX]

I assume that mine spews fuel when riding wheelies. I know it does when I lift the front wheels onto the tailgate and when I pull it off the truck.
If I can replace the float and stop this I will do it. I just was under the impression that "that just happens" with the 300ex.

[bwamos]

You just need to replace the float needle valve. It's a simple fix.

The rubber tip on the end of the needle valve probably hardened and simply doesn't seal anymore so fuel leaks past even with the float pushing it closed.

Sometimes it is just dirty though and gets "stuck open". If you pick up the rear and drop it a few times and it ends up stopping the overflow then it's sticking. If it doesn't you just need a new needle valve.

Just get a rebuild kit from Moose, etc.. Make sure it's a kit that contains the needle valve. Some don't.