Changed my pipes (Vance and Hines) to some bassani road rage (two into one) after I changed them rode the bike around the block a few times and notice when dropping Rpms quickly or downshifting it was popping pretty loud. So I stop and had it in neutral and revved it up and there's flames coming out when the Rpms drop from being revved up high? So I'm waiting on a tuner and going to take my bike in but I'm curious if there's anything I can do in the mean time 2009 dyna street bob

 

Tuning issue. Too much fuel in the wrong areas of the tune, hot unburnt fuel ignites when it hits oxygen at the end of the pipe. Not a horrible thing, lots of high HP cars that are tuned to throw lots of fuel at WOT do it.

Mine did it too, until I got the pipe (road rage as well, and my short shots did too) tuned better.

 

You're experiencing a suddenly lean mixture when you chop the throttle, meaning combustion happens too hot and too quick to burn all the fuel in the cylinder. The result is unburnt fuel making its way into your exhaust and combusting from the heat. The decel pop and the flames won't hurt anything, but if you're running too lean, the heat will start to wear on your cylinder. Since you're waiting on a tuner, the only thing you can really do to richen the mixture (aside from changing parts) is physically block air from getting into the engine. Put tape over a portion of your air filter, for example. If the tuner's not far from getting there, I wouldn't worry about it.

 

No, it's the opposite.

Yes correct.
If you have a tuning box, Sepst or DPV, the good table for solve your problem is the Deceleration Enleanment.
You have to decrease all values from 10% to 50%.
It's for popping at the begining of deceleration.
At the end and during deceleration, poping must be solve by increase VE table at 0% Throttle between 1500 and 4500 RPM.

 

You can get exhaust flames when to lean and to rich, depends on the colour of the flame. If I remember correctly a bluer flame is lean and a golden flame is rich. However another common cause for exhaust flame is an air leak in the exhaust allowing air into the pipe to ignite hot exhaust gases that other wise wouldn't ignite due to not enough air. This can also produce a blue flame and lots of decel popping. Did you change the round exhaust gasket where the exhaust bolts into the head? Good luck in getting it sorted.

 

Not saying it cant happen, but usually an exhaust leak will not produce a visible flame due to the air/ oxygen getting to the mixture before it leaves the pipe and just makes the audible "pop"

 

I'm speaking from my own experience with this very issue on my own dyna wide glide. I made sure it was jetted and tuned properly still flamed. I then thought because I had nothing else to check I would check the gaskets where the exhaust meets the engine because I know that if these leak it can cause decel popping, I had this also. I started it up and yes there was a small leak on both. I replaced both gaskets with genuine H-D ones, the decel popping stopped and so did the flames. I suggest the OP check his if he didnt change them when he swapped the exhaust, or check them anyway as things move when bolting it all togeather as it could be the cause.
Fueling shouldn't be that far out as he has swapped one performance exhaust for another, just a thought.

 

I'll have to check those gaskets again they were a pain in the *** to get in. Maybe they shifted or something which could be causing air leak

 

There are quite a few people out there who'd pay good money to have a bike that pops and shoots flames out of the pipes...because it's "badass".

 

Yup, do that. You need to use the Screaming Eagle flat gaskets not the factory coned/tapered gaskets
Also keep in mind there's a torque sequence for those nuts and they only go to 120 inch pounds.
Book says start in front;
7. Tighten flange nuts (35), at front cylinder studs as follows:
a. Install lower nut and tighten finger tight.
b. Install upper nut and tighten to 9-18 in-lbs (1-2 Nm).
c. Tighten lower nut to 100-120 in-lbs (11.3-13.6 Nm).
d. Tighten upper nut to 100-120 in-lbs (11.3-13.6 Nm).
8. Tighten flange nuts at rear cylinder studs as follows:
a. Install upper nut and tighten finger tight.
b. Install lower nut and tighten to 9-18 in-lbs (1-2 Nm).
c. Tighten upper nut to 100-120 in-lbs (11.3-13.6 Nm).
d. Tighten lower nut to 100-120 in-lbs (11.3-13.6 Nm).