yz450f popping/backfiring

[cojo]

i just purchased my 1st 4 stroke bike a week ago and i notice it seems to pop a lot when i am decelerating. Is this a normal thing or should i be concerned with it? is there anything i can do for this? thanks.

 

[jr.ink]

probably running a little lean for your temp or altitude. The other quick fix is look for ill fitting pipe connections, especially where the header attaches to the motor. Not likely, but airbox leak is possible.

good luck!

 

[WR400Fanatic]

hey, i had lots of problems with my bike popping and fouling plugs at the same time, it sucked! popping is generally a sign of a lean mixture, but since i was fouling plugs mine was obviousely too rich. mine ended up needing a new accelerator pump diaphram. to know if your diaphram needs changed look at the carb where the rod goes into the carb to pump the diaphram and twist the throttle a few times, if fuel comes out around the rod your diaphram is obviously damaged.

 

[biglou]

A little popping on decel is optimum, I'm told. But the lean pilot circuit theorysounds correct to me, especially if it's a new bike. I'd say turn the pilot screw out 1/4-1/2 turn and try it again. Like I said, a couple pops on decel is no big deal.

 

[CR Swade]

Contact James Dean, he is the jetting guru for four strokes. On both my 525 and my WR450 they were jetted lean for Cali air restrictions and popped like crazy. Once the weather gets colder, it can become incredibly hard to start and very lean. His jetting kits richen up the bike to run like it should and will give it a sizable gain in the boost department. Trust me, it is worth every penny, plus the popping, blue pipes and hard cold starting goes bye-bye.

 

[Anssi]

From what I hear and what I have experienced (-03 YZ450F and JD kit) the YZ450F needle is actually pretty close to the ones in the JD kit.

What are the temps and altitude like where you ride, coho? Do turn out the mixture screw a bit and see what it does, especially if you ride in cold temperatures.