Help!!!!! Backfire And Drip

I NOTICED THAT WHEN I LET GO OF MY THROTTLE, ESPECIALLY ON A DOWNHILL MY PIPE BACKFIRES, WHAT SHOULD I DO? ALSO I JUST INSTALLED A FULL PIPE AND HEADER FORM DMC, WHEN I BARELY TURNED IT ON FOR THE 1ST TIME IT WAS SPITTING OUT LIKE WATER FROM THE PIPE AND HEADER JUNCTION? IT STOPPED BUT IS THIS NATURAL? HELP

[trueblue450]

Im not sure but since you just installed a new pipe you probaly have jetting problems. You prolly need to change the jets out but I couldn't explain the water probs.

[WB400ex]

mocazen


i cant explain the water problems but it backfires because you are running it too lean. go a little richer and try it. any ?'s ask me

[MichaelS693]

Im pretty sure the backfireing is the jetting

[Red Rooster]

i think that the backfiring when u r goin down the hill comes from the engine comp. braking i'm pretty shur its normal

[Chef]

nope, its not the compression braking, the compression braking just slows the bike down, and the engine just sounds normal. you are most likely jetted lean. if it does it alot, i would not run it hard. i did a spark plug check on my bike, and it was so lean one time that under a magnifying glass there were specks on the plug. know what those specs are? there are ALUMINUM, as in aluminum from the piston, very very bad thing. needless to say, didnt ride it until we went up a few sizes on the main jet, seemed to help, but we are still dialing it in

wow...your all wrong..the backfire going down hills is from the motor loading up and the excess unburnt fuel burning in the head pipe..and is normal..you can't hear it on a stocker 400 due to the pipe...as for jetting that has to be determined at the plug

[Red Rooster]

thats what i thought

[Red Rooster]

thats exactly what I thought:)

Well, since we all think that we have the perfect answer and no one else can be right too, i will have to say that you are all wrong...(J/K I could be wrong too but I just wanted to say that) In engine mechanics 101 you learn that backfire under decceleration (letting off the gas) is due to a lean condition in the Idle circuit. Meaning a bigger pilot jet or screw adjustment (depending on carb) is needed. Basically as I understand it, it is due to the motor turning at a higher rpm with a very lean fuel mixture (due to no throttle) Going down hill would tend to keep the motor RPM up higher than if you were just on flat ground, thus making the condition worse...

[trueblue450]

thats exactly what I thought :)

[hetrick425ex]

thats what i was ganna say iceman ..... PULL IN THE CLUTCH hahah
:devil

I am glad that you agree with me... I love this forum stuff... My life long goal is only to help others... I get so choked up at the oppurtuninty to make someones day a little better... <sniff, sniff> Whew... I will be ok, it is just all a little emotional... :D

no...i still think i'm right...i'm think the water or something he's talking about is gas too cause i don't know how it could be water

Not to be rude or objectionable, but if there was enough gas in any part of the exhaust to leak out, I am sure he would have already been arrested for explosive manufacturing when the exaust exploded... My car leaks out the exaust every day when I first start it, could it possibly be condensation??? (cold metal vs. hot exhaust???) Just a theory...

Water is a byproduct of internal combustion. It'll do that until the pipe gets hot. Ever notice your car dripping water out of the exhaust while it warms up? Same thing.

The backfire thing could be caused by an air leak somewhere in the pipe causing little explosions when the air gets sucked into a hot pipe while decelerating and mixing with the hot unburned gas in the exhaust.

Did you replace your head pipe gaskets? It could be sucking air where you see water dripping out at the junction.

I agree with everybody! Actually vista cruiser hit it on the head, although a lean idle circuit could be the problem if it only backfires going downhill. If it back fires any other time you decelerate then it's an exhaust leak. Water will run out of a quads' pipe from condensation especially if the engine runs lean!

Basically-- Your probably lean in the idle circuit and main too, although you haven't described any other symptoms. Check the pipe joints ( high temp silicone may be the answer) and the crush washer at the exhaust manifold.

My reasoning is this:
(1) If your engine only backfires going downhill-- Turn the idle mixture screw out 1/2-1 turn.

(2)If your engine backfires any other time you decelerate then your getting fresh oxygen (air) into the exhaust pipe and it is igniting the hot unburned fuel mixture. ie.-- exhaust leak!

(3)Condensation is normal but if you can see a watery mess blow out the back of the pipe when it's started than the main jet is lean or you have an exhaust restriction. Both develop very high exhaust temps and heat the pipe EXTEMELY high. Remember this-- large amounts of water pouring out the exhaust pipe became a common sight only after the advent of the catalytic converter (before you flame me, I know a cat con turns CO, HC, and NOx into CO2, N2, and water!) and the cat con has to be HOT, HOT, HOT to work, about 900-1600 deg. to work properly. My point is, if you have that much water vapor condensing inside you pipe then it's running to hot. Go up one or two main jet sizes and move the needle up a notch.

Sorry, I got caught up in myself! Just reread your post. If it only blew water on the first start up and didn't do it again, then don't worry about it.

Sometimes too much info is as bad as not enough!!!:D

[hetrick425ex]

i am more than sure that iceman is right
there is no way that much gass would be able to pass through it beings that is is a 4stroke and still be a liquid:blah