300EX cuts out an dies going up hill

[2000SPORT]

Okay, got a 300EX. It runs fine as long as it's level. I go up a hill or wheelie, it starts cutting out and sometimes dies. Any idea's? It seems like it's not getting fuel then. It doesn't have to be a very steep hill either. As long as I keep it on the flat it runs great.

[95300exrida]

the carb might be dirty or something plugged up in there

[2000SPORT]

I'll take it apart and give it a good cleaning and see if that helps. Really I dunno what else it could be. I thought maybe the vent hose was kinked or something, but it wasn't, and then I thought maybe I had some bad gas, but I ran the old out and then drained the rest, and put new in. Whatever it is it only affects it on an incline or a wheelie.

[prepracing]

could be trash in carb, bad float or float needle, or if your valve clearances get to loose it can cut and miss fire like that when trying to accelerate (like going up hills )

[2muchquad]

it probably does it under a load such as a hill or wheelie.i would inspect your camshaft,lobes could be severly worn too.otherwise look into the carb:)

[Trevor]

Wile you have the gas tank off check the little filter in the fuel shut off on the tank. I was having a problem something like that aand that filter was cloged.

[bwamos]

Does it do it going down hill too?

If not, as above said, check to make sure your filter screen in your tank isn't clogged.

If it does do it on down hills too...

Is it a stock carb.. or an aftermarket carb like a Mikuni Flat Slide.

A stock carb will have the fuel line in a S shape on the left side of the carb. Some aftermarket carbs require the hose to go over to the right side. Some people take it over the top of the carb intake instead of below it, it will make the fuel stop flowing going up and down steep hills in my experience. I did that at first with my Mikuni Flat Slide carb I used to use.

Other than that.. check your float level.. it may be set too low. When you go up a slight incline the fuel would pool at one end and shut off the valve prematurely causing your carb to suck air instead of fuel.

[2000SPORT]

Thanx for the input. I've been so busy working I haven't had time to tie into it yet. Yeah, it has the stock carb. It doesn't seem to do it going down hill, but I'm not on the throttle then usually then anyways so I wouldn't notice it. I rode it around a little bit tonight. I went up a little bit of a hill. It ran fine, I get to the top on the level and go about 200 yards it starts acting up again then smooths back out. Just something about being tipped back. I'll take apart and clean all the fuel system and see what happens. I doubt it's the cam. I don't have too many hours on it yet, but the valves may be off some. I need to check them anyways.

[Trevor]

Wile you have the gas tank off check it for water and dirt because now would be the time when you have it off. After I cleaned my carb and the filter it worked perfect and it was doing the samething yours is.

[Jake250ex]

i know what it is the exact same thing happened to me. you have a plethora of skinny black hoses coming out of the bottom of your carb, one is clogged with dirt. when you wheeile or tilt it far back fuel is supposed to pour out of it so you dont flood your carb. Anyway, check all the overflow hoses I guarante one is clogged. ;) I wish it was this easy for me - i worked on it forever and spent some $ trying to fix it :(