I'm not a carb guy.... At all.

[MXWarrior323]

I know this sounds so freaking stupid, but i need some help with my 09 kx250f. Its making some quiet crackles on deceleration. Nothing big or loud, but I'd like to see if i can iron it out. I know what I need to do, twist the air screw i think, but if that doesnt work, whats another option... Or is there another technique to get that crackle gone?

[Dragon67]

I'm not really, either, but I am getting better thanks to the guys on this site.  It doesn't sound stupid.  It may or may not be carb related.  Even if it is, it may not be unusual.  If it came on recently, it could be the seal from your head pipe came loose. You could try tightening the head pipe mounting nuts by 1/8-1/4 turn.  Just be careful, because the torque on those is pretty low.  Same with the mid-pipe seal.  When air leaks get into the head pipe it can cause popping on decel, so there you have it.

 

When was the last time you checked your silencer packing?  That could help, too.  Take a video so we can hear what you hear.  That makes diagnostics a lot easier. 

[RUDEDUDE806]

If what dragon mentioned doesn't change the decel pop clean your carb if that hasn't been done recently try to always start adjustments with a clean carb, I have had this issue on a 06 kx250f

Could be dirty jets or fuel screw adjustment

Remember a lil pop on decel is ok but excessive is not.

[MXWarrior323]

Cleaned the carb, and checked the header pipe. The header helped a lil but it still crackles. I know its fine, its so little it wouldnt damage anything, but I'd really like to iron out that annoying sound... Without spending money to take it to a shop.

[MXWarrior323]

I hadn't thought of the muffler packing though... I'll replace that and see if that helps! Any other tips?

[Dragon67]

Cleaned the carb, and checked the header pipe. The header helped a lil but it still crackles. I know its fine, its so little it wouldnt damage anything, but I'd really like to iron out that annoying sound... Without spending money to take it to a shop.

I promise you won't have to take it to a shop. There is a copper gasket between your head and header pipe. You need a new one. It's cheap. Then you need to re mount the exhaust system in the right order.

First, put everything back on and finger tight. Then torque the middle muffler mounting bolt to 15 ft-lb, then the rear muffler mounting bolt to the same. Then torque the head pipe mounting bolts to 11 ft-lbs. Then torque the middle clamp bolt (the last thing you do) to 97 inch pounds. No more snap, crackle, pop. Now, if your mid-pipe gasket is trashed or non-existent, buy one of those, too.

Check back with questions.

[MXWarrior323]

Thanks Dragon you know your stuff!

[Dragon67]

Thanks Dragon you know your stuff!

 

Yeah, well the TT guys on here know their stuff, which is where I learned most of what I know.  Gotta love TT.  ?