After doing the comparison with the other folks with Stage I dynos, is it safe to say you are reasonably satisfied with how the bike runs (except of course for the decel pop)?

Assuming you are just looking to reduce the popping, I would first check for air leaks at the intake (pinched boot between EFI and intake) and the exhaust (gaskets not fully sealed). If there is nothing there, and since you spent a good amount of money on the initial tune, I'd recommend taking the bike back to them and giving them a chance to look it over. They may surprise you and make it right.

If that yields no fruit, before you spend more money on another tune, you might consider trying the decel enleanment adjustment on the SERT. That will cost you nothing to try. I used that to virtually eliminate the decel pop when running VH Short Shot Staggereds, SEAC, and SERT with Stage I canned map.

All three of these options are free to you and one or more may get you to your happy place.

Good luck.

 

No harm.....just annoyingly loud....and dumb.

 

This is for cpiad and hoggymountainbreakdown and for anyone else interested in causes and solutions for decel popping. In spite of what they both believe, decel popping is most often caused by a lean condition, i.e., intake leaks, poor seal at exhaust ports and/or poor connections between the mufflers and head pipes. Check the DynoJet FAQ for solutions to decel popping and this will be confirmed.

Back in my post #7, I stated that decel pop is "usually" an indication of a lean condition. Since the OP had just had the engined "tuned", the first things to check for are intake leaks, exhaust leaks at the cylnder head and at the joint between the mufflers and head pipes. Leaks = air = lean condition.

It is just that when the air fuel ratio is lean enough then it ignites; you will never have a complete burn by this I mean no fuel vapor in the exhaust. So when the mixture climbs to where you have enough air (oxygen) vs fuel and a way to ignite it (exhaust heat) it will ignite. Adding a little fuel will decrease the AFR ratio to more parts fuel than air thus it becomes harder to ignite, i.e., a LEAN condition. Look at it this way when you have a exhaust leak what happens? You get popping on decel. Why?... because you introduce air to the exhaust thus leaning out the mixture.

When all is tight in the intake and exhaust,and you have decel pop there are a few ways to deal with it. Adjust fuel where the decel pop is occurring. Say your running 3200 rpm in high gear and you let off the throttle and it winds down to 2500 rpm and pops. If you add fuel @2500 rpm and 0% throttle (because your TB is closed now) it will raise the fuel AFR to a point that there isn't enough oxygen to ignite the unburned fuel; this might also have to be done at 2% throttle to eliminate it completely. There is also a cooling effect going on now with introducing the extra fuel into the exhaust but that doesn't play as big a part in the elimination process as raising the AFR to a point that it doesn't ignite. Adding fuel to solve the problem = LEAN condition.

Now please note that in my post #7 I stated that decel popping was "usually" an indication of a lean condition. I did not say that decelo popping was "always" an indication of a lean condition or the singular cause for decel popping. Decel popping can be created by a number of factors which are causing a combustion event in the exhaust system including but not limited primarily to a rich or lean condition, an exhaust leak, or reversion in the exhaust system from a free flowing design, short design, or large baffle design.

Because EFI requirements change greatly based on manifold pressure there are very different things going on when the throttle is closed during decel. There is really no right or way to start tuning out decell popping as it can happen from a rich mixture where there is simply unburned hydrocarbons in the exhaust system that ignite.

Bikes will just as easily decel pop from a lean mixture where in this case the exhuast gas temp skyrockets and will super-ignite gasses in the exhaust stream that would not normally ignite. There are also issues due to exhuast leaks where reversion will essentially introduce O2 into the exhaust system and cause popping.

Reversion plays a huge part of decell popping and is inherent in many exhaust designs. In most cases if you have the exhaust sealed at all joints and have a properly tuned bike you can tune most decell popping out, however some "backing down", "gurgling" or small pops would be considered normal.

So, I stand by my original post and statements that decel popping is "USUALLY" an indication of a lean condition and the decel popping can almost always be eliminated if the tuner knows what he is doing and you can't make it pop if you try. I have two built and tuned performance builds, one EFI and one carbed; they don't pop on decel. The EFI did start popping on decel once and the first thing I checked was head pipe connections at the cylinderr head. Guess what, I had lost an exhaust flange nut; replaced, retorqued, hasn't popped since.

Oh yeah, don't expect any better numbers out of a Stage I upgrade.

 

If a bike is tuned on the edge...with aftermarket pipes ....I can make it pop....without really trying.[/quote]



Exactly!

 

Although it is not relevant to the discussion, I beg to differ. Like I said, I have two that will not pop on decel, period, just won't happen.

 

Ok already.....you are king. Feel better?

 

Slowhand, I don't know much about the tuning abilities of Trask, but I do know this.....you have a VERY capable tuner not too far away. Call Steve at GMR Performance in Prescott.

 

Just making a point. You and another were quick to jump on my suggestion that decel popping indicated a lean condition as though I was providing mis-information; can't let that go by unanswered.

It's got nothing to do with feelling better; I just don't let that sort of thing pass. I took exception, made my point and that's it.