Hey guys.. I rejetted my bike,put on a HMF pipe, and removed the airbox lid.
Now I have annoying decel pops..
I am running 128 jet and 3rd notch..
Will moving the needle to 4th notch help?

 

After having numerous off road 4-stroke singles since '79 with aftermarket exhausts, if you're jetted correctly I'll think you'll always get some decel popping. Now the term "some" can vary for many. Jacking up the pilot size or raising the needle might help, but why sacrifice performance and fuel economy to stop a little popping. Now if your decel popping sounds like the first day of water fowl hunting season, then maybe you're way off on your jetting to start with. And in some cases you can worsen decel popping by richening up the engine. Just depends on variables. This guy explains it way better than I do, and he's just one of many with an almost identical description of what's going on and why you'll probably get it no matter what you do...at least in a more performance oriented engine and especially with an aftermarket exhaust.

Deceleration Popping explained

 

You might try a quarter to a half turn out on the pilot screw. Also try this with the lid on but the snorkle removed. Just to see if it helps or hurts then you might have an idea how to or if it needs fruther jetting.

 

The HMF pipe always decel pops. You need to put some exhaust sealant on the joint, this will reduce the popping.

Like TNC says (and this dude knows what he is talking about), a 4 stroke thumper will always decel pop somewhat with aftermarket exhaust.

 

I just finished my re-rejetting this afternoon/evening (90 degrees F @ 1600ft) and the road performance came out pretty good. There is a little bit of deceleration lean popping but as long as it doesn't sound like WWIII back there I'm not too concerned...

 

After changing my needle clip positions about 5 times now on my current set up, I found that moving the needle down (clip up), it will reduce the popping.

To make sure you are talking about the same thing, when you say 3rd notch, you mean from the blunt end ( top as it sits in the bike ) and not the needle end, right?

I started out in the 2nd clip from the top, ran great. Went to the 3rd clip, started popping a bit, even tried the 4th, and then it really popped.

Every bike is a little different so just start playing with it. You can change the needle clips without removing the carb. Takes maybe 20-30 minutes each time.

 

I don't quite believe this statement.

With my pipe, both stock and big bore setups, I was able to tune all the popping out of my bike. Bike runs fantastic, even when hot or cold. It takes a lot of work and trial and error, but it can be done.

In saying that though, a little popping isn't a bad thing.

 

sounds acccuarate to me.. dont think ive heard a bike with a nice exhaust and jetting that doesnt pop.

 

I like poP!

And hate ring ding!

 

I noticed my popping decreased a little bit with my FMF powercore 4 setup after adding a UNI air filter...coincedence?