Help!!!

[trx400ex sport]

can anyone help??when i give it a good shot of gas(only in gear) it makes this loud banging sound.in neutral it dosent make the noise,any ideas what this could be?

[†2005 400ex†]

is it like a backfire bang sound or like a knocking?

[miller821]

Sounds like its backfiring... Either go up or down on your jet and that might help it out (Don't know which way to go though).

[trx400ex sport]

it is a knocking grinding sound

[GPracer2500]

Detonation maybe?

We'll need more info to help:

What mods if any do you have?
What kind of gas are you running?
Does the sound seem to correspond to the RPMs (i.e gets faster or slower as the RPM goes up and down)?
Does it only happen at low RPM, high RPM, or both?
Does it matter what gear you're in?
Where does it the sound seem to be coming from?

...and anything else you can think of. Without being there the details you can provide will guide the usefullness of the advice you may get.

[trx400ex sport]

its all stock,i use 93 octane gas,niose gets worse with high RPM,it happens in all gears,except neutral,sound seems to be comming from the engine....