Ok I got my pipe installed and rejetted and my raptor seems to run great now except for one thing, after I turn it off it makes a real quiet pop. I know I'm not lean by my plugs, if anything I'm running rich. Is this something normal or should I be concerned about it. I'm jetted at 150 155 DJ 3 turns out if your wondering, with 3 small holes in the airbox and a full Yosh. Thanks for the help.

Trevor

 

well, i got a stock raptor, and sometimes i revv it up real high, and then pull the key, and it will make a loud BANG sometimes, how do you shut yours off? I know on Ferrari's the proper way to shut the engine off is to rev it and why'll its revving take out the key, so i do it on the raptor.

 

Its either crappy gas or a bit lean.
If you pull the choke on, and then shut it off, does the pop go away?

 

Usually a pop is caused by a lean condition. Try adjusting the air screw and see if it helps, you really shouldn't be running the screw 3 turns out anyways as it sometimes will vibrate out.

 

I usually let it idle down then shut if off. I dont see how it could be lean with the jets I'm running, the plug tells me its rich. It only does it if I ride around for awhile then shut it off. If I just move it a little and shut if off there is no pop. The only other time it pops is once anc awhile if I run WOT for a little while then let off, it will pop then too but not on just deceleration. That is why I thought it was rich, I could be wrong though.

Thanks for the replies.
Trevor

 

You might be rich on the top, but you can still be lean on the pilot circuit. When are you doing the plug checks, wide open? If so your only testing the main circuit. When you let off and hear a pop or backfire noise its a sign of being lean on the pilot or needle, and in some cases can be corrected using the air screw.

 

my yfz 450 pops when i let of the gas does that mean anything??

 

its completly stock and less than a month old

 

It means its lean on the idle circuit. Where is your idle screw at? Try adjusting it in and see if that helps.

 

is it lean from the factory ? becuase me and my dad have no idea how to do anything with carbs or the engine?