Decel Popping on 2009 CRF250

[cjfolse]

Situation:
I had a 2007 CRF250 with a FMF 4.1 Exhaust and the accompanying megabomb header. I ordered a JD Jetting kit, put the jetting according to kit instructions and all was good.

Settings = taking out the stock 175 main jet and replacing it with a 180 main jet and using the red colored pilot jet with the clip on the 3rd groove from the bottom

I just recently purchased a 2009 CRF250 and moved over the following...
1) Header and Exhaust system
2) Quickshot
I was going to move the jetting over but the 2009 had a 185 jet in it already so I didn't do any jet mods and just moved the full exhaust system over along with the quickshot.

The bike runs fine but backfires a lot. My questions are...

1) Do I need to jet my 2009 bike any different since moving over that exhaust system
2) Am I okay running that pipe system and quickshot on my 2009?

Any help would be greatly appreciated...Thanks!

[ktm300hater]

Decel pops are because it lean on the bottom. The 09 isnt the same bike as an 07 so the jetting wont be the same. I would go up one on the pilot and probably open the mixture screw a little... but without hearing it its hard to say exactly how much. Also decel pops can be caused by a slight exhaust leak, so check that also....

[cjfolse]

Thanks hater, I will give that a shot this week.

[cjfolse]

So I got the Jet Needle out and checked it out. It's currently in the 3rd setting. The book says if I go up to the 1st or 2nd second from the top it will make it leaner. When you said go up to make it run richer did you mean up to the 4th slot because that is what would make it richer right? I may be confused with going up on the needle and going up a numbered slot.

Also, I called FMF to make sure this exhaust and header was right for the 09 and this exhaust system is designed for a 06-09 so I know I'm good there. They also mentioned the main jet wouldn't change for this pipe so I feel like I'm good there but he didn't give me the setting for the clip because he said they have a jet kit for that pipe (which is probably not necessary since the clip is moveable on the stock needle right??).

He also said the pilot screw should be turned out 1 full turn from the seated position and according to the book, the bike came at 1 and a 1/4 out from the seated position. According to the book and what you said, turning it out would make it run richer so why would they tell me to turn it only 1 full turn out?....unless the clip was on the 4th setting right?

The only thing that makes sense to me right now is moving the clip to the 4th setting (raising the Jet Needle) which would lean it out and to start with the pilot screw on 1 full turn out and go from there. I think that's what you told me to do but I am getting confused with the going "up" statement. "up" as an up the needle or "up" as in up a notch to the next higher number?

Thanks again!

[PU300]

one thing to keep in mind when calling a company like FMF ni southern california is that the humudity is about 15% there and generally about 40% here (not lately)

jetting for TX has always been a little different than CA.

you and Bobby are talking about the same thing.... raising the clip lowers the needle. Raising the needle lowers the clip... ettc etc

[ktm300hater]

So I got the Jet Needle out and checked it out. It's currently in the 3rd setting. The book says if I go up to the 1st or 2nd second from the top it will make it leaner. When you said go up to make it run richer did you mean up to the 4th slot because that is what would make it richer right? I may be confused with going up on the needle and going up a numbered slot.

Also, I called FMF to make sure this exhaust and header was right for the 09 and this exhaust system is designed for a 06-09 so I know I'm good there. They also mentioned the main jet wouldn't change for this pipe so I feel like I'm good there but he didn't give me the setting for the clip because he said they have a jet kit for that pipe (which is probably not necessary since the clip is moveable on the stock needle right??).

He also said the pilot screw should be turned out 1 full turn from the seated position and according to the book, the bike came at 1 and a 1/4 out from the seated position. According to the book and what you said, turning it out would make it run richer so why would they tell me to turn it only 1 full turn out?....unless the clip was on the 4th setting right?

The only thing that makes sense to me right now is moving the clip to the 4th setting (raising the Jet Needle) which would lean it out and to start with the pilot screw on 1 full turn out and go from there. I think that's what you told me to do but I am getting confused with the going "up" statement. "up" as an up the needle or "up" as in up a notch to the next higher number?

Thanks again!

My mixture screws are like 2.5 out. Normally when saomeone says raise the needle they mean lower the clip...kind of confusing sometimes. Heres what I would do to start. Go one size bigger on the pilot jet, then start the bike and let it warm up. Get a screwdriver that you can adjust the mixture scrw with, while the bike is running slowly close the screw till it starts to stumble. then open it back up until the idle smooths out and sometimes it will even idle faster. once there give it another 1/4 turn... go ride it and see how it acts after that, that should solve the pop...if not lower the CLIP to RAISE the needle, then readjust your mixture screw

[cjfolse]

Got it, just ordered the next size bigger pilot jet....hopefully it will be in tomorrow. Thanks for the help, it's starting to make sense.