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  1. #1
    Beetle Bagged Hooligan
    KotF Firestarter

    Join Date
    Jun 2004
    Location
    Central NY

    Exhaust popping on decel?

    This has probally been asked a 1,000 times on here- 1,001 now but what causes the popping on decel? I added a D+D can to my stock system and then could really notice it. Last year I didn't mind it but now after only 3 rides this year it's starting to annoy me more.
    I asked Boz about it but he wasn't sure, ("maybe just stuff a rag in it")
    Thanks for any info or referal to a thread --Greg D.
    Last edited by Greg D.; 04-19-2009 at 07:53 PM. Reason: spellin'
    "Never ride faster than your guardian angel can fly"

    ZRXOA # 5243

  2. #2
    BadAss Hooligan
    Join Date
    Oct 2003
    Location
    03076 / 33917

    Re: Exhaust popping on decel?

    unseal the mixture screws, dial them 3 turns out, remove the octopus, plug the holes
    ZRX 1200R 7/2003 -5/15/2015 (sold to a good home)

    ZZR1200 April 2009 -September 2014 (dealer trade in)

    2017 Concours 14 ( June 2018 -current)
    HD 2013 FLHTK Stage 4 ( Sept 2014-Current)
    HD 2003 FLHTCI cammed. closed loop FI, upgraded suspension ( Sept 2005 - current)

  3. #3
    BadAss Hooligan
    Join Date
    Aug 2006
    Location
    Rockwell, iowa

    Re: Exhaust popping on decel?

    I'm sure somebody will be along shortly and bust your chops for not using the search tool.


    Maybe we should just have Chuckc lock all threads and not allow any posting cause you can find it all with a search. Then, there is no point in having a ZRXOA 'cause nobody and "talk" to anybody else.



    rant over
    ZRXOA 7793
    Just because you can, doesn't mean you should

  4. #4
    Formerly A-Train
    Join Date
    Jan 2005
    Location
    Orange County, CA

    Re: Exhaust popping on decel?

    Deceleration Backfire is caused by fuel burning in the exhaust manifold or header.

    No ifs ands or buts, thatís what causes it. And...

    A motor in perfect tune will exhibit deceleration backfiring.


    And...

    Getting rid of the popping noise means de-tuning your motor.

    If youíve just got to eliminate popping, your motor is going to be forced to run rich to do it, and that isnít necessarily a good thing.

    Now for a nice trick question......

    If popping is due to unburnt gas, why does enriching the fuel mixture --- i.e. adding more gas - make an engine stop popping?

  5. #5
    kfoster
    Guest

    Re: Exhaust popping on decel?

    Can a rabbit be used as either a partial or complete anwser to this question?

  6. #6
    Beetle Bagged Hooligan
    KotF Firestarter

    Join Date
    Jun 2004
    Location
    Central NY

    Re: Exhaust popping on decel?

    Quote Originally Posted by A-Train View Post

    Now for a nice trick question......

    If popping is due to unburnt gas, why does enriching the fuel mixture --- i.e. adding more gas - make an engine stop popping?
    Got me? I asked the question in the first place. So what am I to do... It (the popping bothers me). --Greg D.
    "Never ride faster than your guardian angel can fly"

    ZRXOA # 5243

  7. #7
    Sweet Pee
    Join Date
    Dec 2005
    Location
    Living life carefree!!!

    Re: Exhaust popping on decel?

    I just know this....while tuning my harley and looking at the closed throttle decel. a/f it went way way lean and would pop and backfire. I had the computer add fuel till it almost went away and a/f is closer to were it needs to be. I like a bit of popping but hey thats just me. No performance lose or gain in doing this on my DX. But it is fuel infected.

    My Rex did lower the a/f as Atrain said but if was not significant at rpm but will mostly affect your idle a/f. I would turn the pilot screw out 1.5 turns each as a starting point if you have the airbox
    #7754

    I love my Boobear

    [QUOTE=SteddyTeddy;4049441]Bullchit, bullchit, bullchit!

  8. #8
    Licensed to post
    Join Date
    Apr 2009
    Location
    Arlington VA

    Re: Exhaust popping on decel?

    """"Now for a nice trick question......

    If popping is due to unburnt gas, why does enriching the fuel mixture --- i.e. adding more gas - make an engine stop popping?""""


    Then.... she is a witch??? Burn HER

  9. #9
    BadAss Hooligan
    Join Date
    Feb 2005
    Location
    Montana

    Re: Exhaust popping on decel?

    Quote Originally Posted by Greg D. View Post
    Got me? I asked the question in the first place. So what am I to do... It (the popping bothers me). --Greg D.
    earplugs?




    I like when my zx10 shoots flames out the back. But if I hold the tiniest bit of throttle I can make it not happen..........but I usually dont do that......like playing cards in spokes, I get to pretend I'm one of the big boys (moto gp)

  10. #10
    Legal Eagle
    Join Date
    Oct 2004
    Location
    Tallahassee, Fl

    Re: Exhaust popping on decel?

    The pop didn't bother you before so ditch the D&D cop magnet.

  11. #11
    Licensed to Mod
    Join Date
    Feb 2009
    Location
    South Florida

    Re: Exhaust popping on decel?

    Check the entire exhaust system for any leaks. You can also create a LITTLE backpressure with a shoptowel over the can. You would be surprised how sealing a system can eliminate the popping on decell. Try this before messing with the a/f mixtures. Good luck

  12. #12
    DonBob Hooligan
    Join Date
    Mar 2002
    Location
    Between Here And There

    Re: Exhaust popping on decel?

    What JML said.

    Any sources of outside air going into your exhaust system can cause popping.

    I think it's been clearly posted that the REX is lean from the factory.

    I ended up increasing my pilot jet size to stop the popping, even after Ivan's jet kit.
    2002 Gasta Glas Ri,
    The 2007 Kaws On The Farm, Hooligan's Choice Award!
    The March 2011 Bike Of The Month!
    The 2011 ZRXOA Bike Of The Year!
    "THE FASTEST REX IN PLATTEKILL, NEW YORK!"
    2005 Raon Ri Masc
    The October 2014, Bike Of The Month
    The August 2018, Bike Of The Month!

    The 2018 ZRXOA Bike Of The Year!
    "THE FASTEST REX IN PLATTEKILL, NEW YORK!"

    1999 "The Lone Warrior" ZRX1100R
    1996 Giggle Bike,
    1988 Nekid Gixxer,
    1979 Strumpet

  13. #13
    aka Captain Bunnyman
    Join Date
    Apr 2006
    Location
    Rhode Island

    Re: Exhaust popping on decel?

    The first thing you should check is your gigly connectors.......if they are ok....enjoy some Kamakaze shots!!
    SPEEEEEED SLOWLY



    SNERR : Ride places & Eat things! (And see BISON!!)
    President to the President
    Capt.Bunnyman A.K.A Bison hunter

    2005 zrx1200

  14. #14
    Clockwork Hooligan
    Join Date
    Sep 2004
    Location
    Mich

    Re: Exhaust popping on decel?

    It may be your muffler bearings, have them checked by someone on the board.
    "I got a gibson without a case, but I can't get that even tan look on my face"

  15. #15
    MyPalDal
    Join Date
    Nov 2004
    Location
    Rhode Island

    Re: Exhaust popping on decel?

    I had terrible popping on decell yesterday
    but I had a side of baked beans at lunch
    with the Bison Brothers* at Hooters.



    *Also known in a previous life as "bad influences".
    Just say no to mumbo jumbo.

    I doubt. Therefore, I might be.

    SNERR: Southern New England Rex Riders;
    Ride places. Eat things.

    BOTM July '11
    Iron Butter #38409

  16. #16
    Legal Eagle
    Join Date
    Oct 2004
    Location
    Tallahassee, Fl

    Re: Exhaust popping on decel?

    Quote Originally Posted by Dallas View Post
    I had terrible popping on decell yesterday
    but I had a side of baked beans at lunch
    with the Bison Brothers* at Hooters.


  17. #17
    High VOLTage
    Join Date
    Jun 2006
    Location
    SE Michigan...Just this side of Heaven!

    Re: Exhaust popping on decel?

    If you added a can that allows more air flow, then you
    need to add more fuel by turning out the low/idle mixture
    screws as someone already mentioned.

    Believe it or not, too lean a mixture on decel can cause popping.
    There is a built in circuit (coasting enricher )that is suppose to enrich
    the mixture on decel under normal conditions, but you
    have changed the back pressure of your exhaust system
    and so now you have to adjust the mixture screws.

    FUEL CIRCUITS

    Carbs are such that they cannot meet all the different running situations with one single system. Starting, idling, acceleration, deceleration, and steady running all impose different fuel requirements on carbs. Carbs also have to handle different engine speeds, different loads, different engine temperatures and other variables. So we find that CV carbs need three distinct "circuits" or fuel delivery systems to meet these different needs.

    An addition to this circuit is found on later Hitachi and all Mikuni carbs. This is the "coasting enricher".
    A typical problem in earlier carbs was the fact that when you chopped the throttle (closed the butterfly) on deceleration, there would not enough fuel in the mixture at the (at that moment) high revs to allow the engine to fire consistently. You would then get a "lean misfire". That is, the engine would fail to fire, and the unburned mixture (lean though it was) would enter the exhaust header. Then when the engine next fired, you'd get a backfire. (So backfiring on decel is typically a lean condition, and not "loading up" as some people think.) The solution they came up with was to reduce the amount of air in the "airbleed" circuit by about half, meaning the fuel content hitting the bore from the pilot oulet was much higher than the normal idle fuel mixture you get on closed throttle. Once the revs came down, the full air bleed would be restored for proper idling. The "coaster enricher" is activated by the strong vacuum created in the carburetor holder (intake stub) byhigh revs when the butterfyl is closed on decel.

    Of special note: we now understand that those adjustment screws only affect the pilot circuit, and mainly the mixture on idle and decel.

    Ps. Thank ChuckC for setting me straight and me for remembering it...
    Last edited by Pal Handy; 04-20-2009 at 11:01 PM.
    Quote Originally Posted by Jesus View Post
    Greater love has no one than this, that he lay down his life for his friends..
    "God, I know that I am a sinner. I know that I deserve the consequences of my sin.
    However, I am trusting in Jesus Christ as my Savior.
    I believe that His death and resurrection provided for my forgiveness.
    I trust in Jesus and Jesus alone as my personal Lord and Savior.
    Thank you Lord, for saving me and forgiving me! Amen!"

  18. #18
    Formerly A-Train
    Join Date
    Jan 2005
    Location
    Orange County, CA

    Re: Exhaust popping on decel?

    AGAIN...popping caused by unburnt gas in header/exhaust.

    Because its tuned right, it pops. When you close the throttle on decel, you slam the air intake shut, leaving fuel in engine.

    To stop the pop, increase A/F mixture.

    POPPING IS NATURAL. NOT POPPING IS UNNATURAL.

    A basic explanation is if you add more fuel, i.e. richen up the a/f mixture, then you get higher temp and pressure and all gas ignites. And no popping.

    But then you are running out of tune.

    Or you could slowly throttle down and not quickly release the throttle.

    And yes, A/F screws in stock carbs are a bitch. And some bikes even inject air into exhaust stream to MAKE IT POP. So you don't expel unburnt fuel.

  19. #19
    Hooligan Express
    Join Date
    Feb 2005
    Location
    Mountain Top PA

    Re: Exhaust popping on decel?

    Quote Originally Posted by kfoster View Post
    Can a rabbit be used as either a partial or complete anwser to this question?
    Kenny, you kill me today !!
    "By The Boston Rexer....Anyone who can pick me up and toss me into a horse pasture with one hand is definitely going to be my bouncer.
    As we age our wisdom grows in ways our youth would have never understood.

    "OK... money to KOTF. LOL. Anxious to see you there.
    Just don't touch me"

    http://www.youtube.com/watch?v=M3pPL...eature=related

    2001 GREEN ZRX 1200 DRAG BIKE
    Hooligan #6583
    The Hooligan Express !!
    MOUNTAIN TOP PA

  20. #20
    Beetle Bagged Hooligan
    KotF Firestarter

    Join Date
    Jun 2004
    Location
    Central NY

    Re: Exhaust popping on decel?

    Calgon, take me away!!
    So I'm not wearin' ear plugs, losing the "cop magnet", answering with rabbits (WTF Ken???) or listening to ANY of "The Wrong Crowd" SNEER guys (ok Eric, maybe a few Kawikazis)
    So I'll go with A-Train's answer & try it, about where should the A/F screws be set when done? Stock is a bitch huh? Gotta love it... Thanks for all the advice guys Ken, we'll talk later! --Greg D.
    "Never ride faster than your guardian angel can fly"

    ZRXOA # 5243

  21. #21
    kfoster
    Guest

    Re: Exhaust popping on decel?

    Ask A-Train about the bunnies.....

    He will give you the straight poop.

  22. #22
    ZRXBubba
    Guest

    Re: Exhaust popping on decel?

    Check for a banana in the tail pipe.


  23. #23
    Beetle Bagged Hooligan
    KotF Firestarter

    Join Date
    Jun 2004
    Location
    Central NY

    Re: Exhaust popping on decel?

    Quote Originally Posted by kfoster View Post
    Ask A-Train about the bunnies.....

    He will give you the straight poop.
    Kenny, bunnies have little round turds- sorta like coco puffs
    'Yo man, I ain't fallin' for no banana in 'da tailpipe either"! --Greg D.
    "Never ride faster than your guardian angel can fly"

    ZRXOA # 5243

  24. #24
    kfoster
    Guest

    Re: Exhaust popping on decel?

    Click Below for the bunnie fable!

    Bunnie Fable link

  25. #25
    Jethro
    Guest

    Re: Exhaust popping on decel?

    Quote Originally Posted by A-Train View Post
    AGAIN...popping caused by unburnt gas in header/exhaust.

    Because its tuned right, it pops. When you close the throttle on decel, you slam the air intake shut, leaving fuel in engine.

    To stop the pop, increase A/F mixture.

    POPPING IS NATURAL. NOT POPPING IS UNNATURAL.

    A basic explanation is if you add more fuel, i.e. richen up the a/f mixture, then you get higher temp and pressure and all gas ignites. And no popping.

    But then you are running out of tune.

    Or you could slowly throttle down and not quickly release the throttle.

    And yes, A/F screws in stock carbs are a bitch. And some bikes even inject air into exhaust stream to MAKE IT POP. So you don't expel unburnt fuel.


    Correctamundo..........a perfectly tunned machine WILL pop on complete throttle shut off, a little anyway.......not ridiculous like yours, 'cause it is properly tunned for it's header............yours is not.............JMHO

    I love the pop on decel..............just boils my blood.........always has, always will.......mine is a monster, with the Megaphone, IT is truly Obnoxious Just hte way I like it

  26. #26
    Official ZRXOA DA - 2006
    Join Date
    Jun 2006
    Location
    niagara falls ny

    Re: Exhaust popping on decel?

    HEy greg......try repacking the thing...the guts are prolly burned out of the thing....I know ya havent done it.....or, I will sell you my full system and you can make more power and sound cleaner!!! My bike was so much nicer after the repacking.....as I am sure most who have ridden with me might agre...lol


    Mors ultima linea rerum est.
    "Death is everything's final limit"





    Oderint, dum metuant.
    "May they hate me, if only they fear me"

  27. #27
    Radical Rocker
    Join Date
    Oct 2005
    Location
    Castile NY

    Re: Exhaust popping on decel?

    Quote Originally Posted by jinxsters187 View Post
    HEy greg......try repacking the thing...the guts are prolly burned out of the thing....I know ya havent done it.....or, I will sell you my full system and you can make more power and sound cleaner!!! My bike was so much nicer after the repacking.....as I am sure most who have ridden with me might agre...lol
    Greg, When I run the D&D can, popping was terriable on decl, put in a jet kit, and still had to open the A/F screws 1.5 more. Roll out of the throttle 98%, or shift down at low rpms to minamize the louad popping. Its a ture Kawasaki if it pops on decl.... You have minamized much of the back pressure on the engine now, it will always be with you. My meg on hi rpm run down pops and the bike is properly tuned.. I dont think stopping it is possible..
    Lead, follow or get out of the way...
    2004 Silver Rex OA#8747

  28. #28
    BadAss Hooligan
    Join Date
    Apr 2006
    Location
    John's Island, South Carolina

    Re: Exhaust popping on decel?

    I never noticed a thing wrong when I first got the ZRX. Right after I installed a Kerker canister the decel popping was bad. I took the carbs off to clean them out and found the number three fuel screw was turned all the way in. That was the problem.

    That stock canister sure does quiet a lot of things down.

  29. #29
    East Coast BRUCE!
    Join Date
    Dec 2001
    Location
    shelton connecticut

    Re: Exhaust popping on decel?

    wouldn't be my ride without it.sorta dig the rumble myself
    stay off the rear brake.

  30. #30
    Legal Eagle
    Join Date
    Oct 2004
    Location
    Tallahassee, Fl

    Re: Exhaust popping on decel?

    Quote Originally Posted by u wish u could ride View Post
    wouldn't be my ride without it.sorta dig the rumble myself
    +1 The pop kinda lets me know there is a ferocious beast between my legs just dying to break free.


 

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