sleddex

Member
Mar 17, 2004
5
0
Hello all, your input here is much appreciated as I am a rookie at the dirt bike game.

I recently purchased a used 2002 KDX 220 and took it out for its first half decent test today.

I think it rode great except towards the end of the ride, (about 1 hour long) I experienced two symptoms.

The first was a hissing sound which seemed to be coming from underneath the gas tank and in the engine area. At times I heard it while moving, other times I heard it while at a stop. It came and went, but only at the end of the ride.

The second was that two times it stalled on me in mid throttle, like it just ran out of gas.

I checked my tank, and there was still some in the bottom of the tank, but in using a flashlight, there is a white stick showing at the bottom of the tank. The fuel line is about 2 inches below that.

Does anyone have any thoughts on these two issues? Thanks.
 

Bubbie3737

Member
Feb 28, 2004
50
0
it will act like it's out of gas with quite a bit in there, flip it to reserve when you get low, the reserve comes on pretty early on our bikes. is the air box lid off? I heard this can make a hissing, i have mine off but haven't noticed a hiss, it might though
 

dsndblm

Member
Jul 12, 2003
167
0
Just a thought since I just replaced mine... Check the rubber boot that goes from the airbox to the carb. Maybe it is loose or cracked. You could have an air leak.
 

Canadian Dave

Super Power AssClown
Apr 28, 1999
1,202
0
If you could see a white tube extending up from the bottom of your talk chances are good it acted like you were running out of gas because it was. The tube is the fuel inlet and if the pet c o c k was in the "on" position then likely you were sucking air. Turning it to “Reserve" should allow you to more fuel but again if you could see the tube you were very close to empty already.

The hissing may be some air trapped in the cooling system. Have a look at the top of the cylinder and you'll see a casting with a 10mm bolt in the top of it. This is the air bleed bolt. It is hollow with a hole through its side about half way up. Loosen the screw until antifreeze begins to flow. This should allow all the air to escape the system. You may need to do it a couple times. Be sure to check the coolant level as well. Just remove the rad cap and you should see antifreeze. Do both with the engine cool or you run the risk of getting burnt. Other hissing noises could be the result of the engine overheating. Next time it is hissing have a look at the antifreeze overflow tank and see if coolant is being discharged into it, a sure sign of overheating. It could be that running with a low fuel level was depriving the carb of gas at times resulting in a temporary lean condition. Lean = high engine temps which could explain the possibility of over heating and the fact that it was happening at the end of the ride when the fuel level was at it lowest.

David
 

skipro3

Mod Ban
Dec 14, 2002
902
0
Yet another possibility for the hissing:
Your gas cap should have a hose running from it with a device that allows air to escape the tank but not fuel. When you are low on fuel, and bouncing around down the trail, the gas will be shaken up enough that it will hiss out the cap's vent line. Depending on where that vent line runs, you could be hearing it from under the tank.
One way to simulate this is to blow into the air line when the tank is partly empty and then remove your mouth from the hose. You will hear a hissing coming from the hose. If that is the same sound you heard on the trail, then there you go!
Good luck and let us know what you find out.
 

sleddex

Member
Mar 17, 2004
5
0
Ok, thanks for all the great help. I bled the coolant as Dave suggested, I don't think there was hardly any air in there as coolant came out immediately. I checked the carb boot, no cracks, it was a tight fit around the carb. I checked the coolant level, all the way to the top. The overflow tank is at the full level.

I checked the spark plug, it was a little loose, nothing major though.

I checked all the coolant lines, all connections seem tight, no cracks or bad hoses.

So, I think what has happened is as Canadian Dave has suggested. I was getting so low on fuel, and not having the fuel throttle to the RES mark, it was just sucking air. Next time I ride I will let you all know how it went with a full tank of gas.

Thank you again.
 

Top Bottom