Popping

[rooster_20]

When I go down a hill and let my ex "hold itself back" and it pops with just a little backfire does this mean im jetted to lean?

what i heard this is caused by is eather
lean or
a leak some wair
or no back pressure

but on my 400ex it was doing that because it was actuly ritch.

[pit/wood]

I would check my float level. If it occurs only when going down a hill it could be that you are leaning out due to a low fuel level in the float bowl.have you done any work on it lately? If you have an exhaust leak at the exh.port it will let air into the exhaust,during decell there is a small amount of fuel that enters the exhaust. normaly there is no oxygen to allow it to burn. if you have an exhaust leak it allows 02 to enter your headpipe and provide the fuel with a way to ignite. It can damage your pipe and in bad cases burn your exhaust valves . This is how it could be in your case .

[rooster_20]

Its on decel and not just when I go downhill im thinking im too rich or lean

Originally posted by rooster_20
Its on decel and not just when I go downhill im thinking im too rich or lean

white plug = lean
blackish/oily plug = ritch
tan= perfect

[GPracer2500]

Originally posted by rooster_20
Its on decel and not just when I go downhill im thinking im too rich or lean

Very likely a lean pilot circuit.

What is your elevation, bike settup (i.e. intake/exhaust), and current jetting?

my old trx500 4x4 did that when i took the spark arestor out i think it was no back presser

Originally posted by 89honda 250x
my old trx500 4x4 did that when i took the spark arestor out i think it was no back presser

in a stock pipe you can take the spark arrestor out and you will still have back pressure.

[400exrider707]

So far everything sounds wrong.....

Its too lean on idle. You need to richen up your air mixture screw. Turn it in a 1/4 turn at a time until the popping goes away.

[Scro]

Originally posted by 400exrider707

Its too lean on idle. You need to richen up your air mixture screw. Turn it in a 1/4 turn at a time until the popping goes away.

If you turn the mixture screw in, that makes him more lean doesn't? Shouldn't he turn it out?

[GPracer2500]

Bama450r is correct. He's on a 400EX--it has a fuel screw NOT an air screw.

Turn a fuel screw out to richen the pilot circuit.
Turn an air screw in to richen the pilot circuit.

Carburators have one or the other. You can tell whether a carb has an air screw or a fuel screw by its location on the carb. Fuel screws are on the engine end of the carb. Air screws are on the intake end of the carb.

In general, four strokes have fuel screws while two strokes have air screws.

Regarding this....:

my old trx500 4x4 did that when i took the spark arestor out i think it was no back pressure
...the reason was because when you removed the spark arrestor you increased the ability of the engine to flow air. More air with the same amount of fuel (i.e. no jetting change) = leaness = popping on deceleration.

[400exrider707]

Originally posted by bama450r
If you turn the mixture screw in, that makes him more lean doesn't? Shouldn't he turn it out?

Yep sorry about that, I knew but I still put down the wrong thing...:rolleyes: Anyways baba you are correct.

[Honda TRX250ex]

My quad does the same thing and its jetted perfectly.

[Scro]

Originally posted by Honda TRX250ex
My quad does the same thing and its jetted perfectly.


If you are jetted perfectly and still have popping on decel, you have an exhaust leak somewhere.

[Honda TRX250ex]

Originally posted by bama450r
If you are jetted perfectly and still have popping on decel, you have an exhaust leak somewhere.
Well, i know my header isnt leaking. Is this bad?

[PismoLocal]

Originally posted by Honda TRX250ex
My quad does the same thing and its jetted perfectly.

If your quad does that too then im just gonna go out on a limb and say your carb probably isnt jetted perfectly.

[rooster_20]

I have the mods in my sig. I live at about 1800ft and my plug looked ok. I also know that there are no leaks? Maybe my jetting is a little off. Im getting a new airbox lid and then I will rejet.

[400exrider707]

Originally posted by PismoLocal
If your quad does that too then im just gonna go out on a limb and say your carb probably isnt jetted perfectly.


Exactly. How do you know its jetted perfect? The plug might look ok, but thats because most of your riding probably isn't done at idle. If its popping on decel then richen the mixture screw 1/4 turn at a time, and I bet it goes away.