My dad has a 2000 honda 450 es forman that every so offten when you slow down and downshift she lets out a backfire. Is there any way of fixing this or is it hurting anything.

 

Open the pilot screw about 1/4 turn , if it still does it remove the pilot screw and check the tip for black carbon built up on it ..

 

I am not quite sure that screw is the pilot. Can you please help me out in this. http://houseofmotorcycles.bike...OURTRAX+FOURMAN+ES.asp

 

#6

 

spark arrestor? my friend had a chinese offbrand bike that did that im pretty sure it is is from fuel left over in the engine when u let off the gas

 

Deceleration backfire is a sign that it is running lean. The pilot screw is a good place to start.

Also, be sure you don't have a leak in the intake boot. Take off the air filter, hold your hand over the opening and carnk the engine a couple times. A vacume should form, and it should not go away quickly.