Popping on decel

Wingboy

Wingboy

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Crashed my track only 944 Ducati hard enough that it needed new exhaust.All the other damage was bodywork and controls.It had a pair of really big Akra's on it before and didn't backfire or pop when downshifting.Now with a pair of Remus cans installed,it pops with every downshift.(only a run up and down my street).It's fuel injected,so i don't think anything could have changed.Could a slightly more restrictive exhaust cause this?Do i need an expensive dyno session now to remap?
 
check for exhaust leaks. if all thats changed is the cans then might have a leak somewhere in the system
 
Wingboy said:
Crashed my track only 944 Ducati hard enough that it needed new exhaust.All the other damage was bodywork and controls.It had a pair of really big Akra's on it before and didn't backfire or pop when downshifting.Now with a pair of Remus cans installed,it pops with every downshift.(only a run up and down my street).It's fuel injected,so i don't think anything could have changed.Could a slightly more restrictive exhaust cause this?Do i need an expensive dyno session now to remap?
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With the R6 peeps, when they change the factory exhaust they get LOTS of pop, gurgle and backfire on deceleration! If the bike has a fuel management computer (i.e. power commander) or a reflashed ECU adding extra fuel on the deceleration section seems to help a lot:

Power_Commander_Idle_settings.png


http://www.youtube.com/watch?v=FI4djEs1Cws&hd=1

Does your bike have a "smog" system, fresh air injection system, PAIR, AIS, etc.!? Usually plugging that up so it can't suck fresh air (or on the R6 we rip out ALL the smog stuff, hoses, AIS pump, etc. then slap on "smog block off plates") will correct all or almost all of the pop and backfire.

I'm not sure what type of options are available for your Duc, never worked on one :)

-Jamie M.
 
I didn't put any sealant on the can to header joint.That's worth a try.The bike is a retired racebike with no smog stuff other than the crankcase breather that dumps into the airbox.No p.c. on it.I assume that the ecu can be remapped.I just don't have $400 to spend on dyno time.
 
My bike does it all the time. I do know it's jetted a bid lean on the low speed circuit. Fine with me, it's not really harmfull in any way.
 
Took the cans off and sealed them with Permatex copper sealant.Couldn't take it out for a quick one down my street today tho.Saw a few cops around.
 
Wingboy said:
Took the cans off and sealed them with Permatex copper sealant.
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Where'd you get the Permatex Copper? I want to two canadian tires and both of them only had up to Ultra Black :(

-Jamie M.
 
I think i got it at crappy tire.But it was about 8 years ago.Surprised it was still good.
 
Leaking at the can/pipe junction is NOT going to make it "pop" on deceleration.
Leaking at the head/pipe junction will.
 
Found a big parking lot this morn to get thru 1st and 2nd.It only pops with a completely closed throttle.I wonder if just turning in the air bleeds a 1/2 turn will richen it up enough? It only pops once when i close the throttle,but it's very annoying and it never did it before i crashed it.
I guess it could be a tiny leak at the head junction tho.The only way to find out is to totally remove the system and put new gaskets in i think.
 
Leak where the header joins to the cylinder head. Most bikes have a compressible copper gasket that goes in there, which you are supposed to replace.

FWIW, popping on deceleration is not something that warrants remapping or rejetting on its own account. Driveability issues warrant remapping/rejetting. If popping on decel is a side effect, so be it.
 
Brian P said:
Leak where the header joins to the cylinder head. Most bikes have a compressible copper gasket that goes in there, which you are supposed to replace.

FWIW, popping on deceleration is not something that warrants remapping or rejetting on its own account. Driveability issues warrant remapping/rejetting. If popping on decel is a side effect, so be it.
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So,do you think i should put some "permatex copper" in with the existing gaskets,or replace them?
And what do you mean by "so be it"?
 
Wingboy said:
So,do you think i should put some "permatex copper" in with the existing gaskets,or replace them?
And what do you mean by "so be it"?
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have you looked over the little things like airbox being on properly....exhaust joints being joined up properly.

Persoanlly my 636 used to run WAY too rich when I acquired it...with a full length ARKA can it used to shoot flames on decel.....now with a fuel management system, and even with a stubby akro can it runs smooth....better fuel economy...no flames and no popping.
 
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