Backfire

Results 1 to 8 of 8

Thread: Backfire

  1. #1
    Bike
    2004 F650GS
    Join Date
    Sep 2015
    Location
    Suriname
    Posts
    4
    Post Thanks / Like

    Default Backfire

    Hello, my 2005 twin spark backfires when i start it and it idles. Even when warm it will backfire. Without the air intake i will see the explosion in the intake. As soon as it backfires the engine shuts down. I have replaced the complete throttle body with throttle position sensor and idle air control. I did not have a new injector so i used the old one. I do not think that the injector drips because if i take the tube off after a few days it will still be well pressurized. The throttle body came from a single spark version. Also replaced the air temperature sensor. The bike starts easy and drives well. Does anyone ever experienced this? Hope i can get help solving this problem. I was even thinking that it might be that the timing is off.

  2. #2
    Bike
    02 dakar
    Join Date
    Dec 2019
    Location
    Scarborough
    Posts
    54
    Post Thanks / Like

    Default

    Air leak, intake or exhaust ?

  3. LikesDansin liked this post
  4. #3
    Bike
    2004 F650GS
    Join Date
    Sep 2015
    Location
    Suriname
    Posts
    4
    Post Thanks / Like

    Default

    Quote Originally Posted by Dakardave View Post
    Air leak, intake or exhaust ?
    do you mean an air leak trough the valves. I checked the intake for cracks but couldn't find any. I thought that it might be a leaking valve but it doesn't happen all the time. It will run good for about 10s and than backfire

  5. Remove Advertisements
    F650.co.uk
    Advertisements
     

  6. #4
    Bike
    05 Dakar
    Join Date
    Dec 2006
    Location
    Ombersley, Worcs
    Posts
    1,183
    Post Thanks / Like

    Default

    If the intake is sealed tight then check the exhaust for leaks at the manifold and joint with the rear silencer.

  7. #5
    Bike
    2004 F650GS
    Join Date
    Sep 2015
    Location
    Suriname
    Posts
    4
    Post Thanks / Like

    Default

    Quote Originally Posted by Dansin View Post
    If the intake is sealed tight then check the exhaust for leaks at the manifold and joint with the rear silencer.
    hmmm, i purchased the bike a few years ago at an auction. When i was fixing it i drilled the left closed silencer open, wanted more noise from the exhaust. I will give it a try to see what happens. Other than that i have never noticed other leaks in the intake or exhaust

  8. #6
    Bike
    GS/Gd Dakar 2003
    Join Date
    Oct 2008
    Location
    wakefield
    Posts
    1,674
    Post Thanks / Like

    Default

    Quote Originally Posted by ptrustfull View Post
    hmmm, i purchased the bike a few years ago at an auction. When i was fixing it i drilled the left closed silencer open, wanted more noise from the exhaust. I will give it a try to see what happens. Other than that i have never noticed other leaks in the intake or exhaust
    you may have introduced air leak half way through the exhaust system by drilling into the "Cat" , (left hand silencer) exhaust gases pass through the cat before exiting thru the right hand silencer . See if sealing it makes a difference , least eliminated this if still back fires

  9. #7
    Bike
    02 dakar
    Join Date
    Dec 2019
    Location
    Scarborough
    Posts
    54
    Post Thanks / Like

    Default

    Squirting wd 40 or damp start around the intake used to be a favourite while engine running . If rev changes you know it's suckling air into the engine. fresh pair of eyes also good

  10. #8
    Join Date
    Apr 2019
    Posts
    481
    Post Thanks / Like

    Default

    The original post seemed to imply the issue was 'spitting back' rather than 'backfiring', the difference being that the 'explosion' is occurring on the inlet side rather than the exhaust side. That said, drilling holes in an exhaust system to let air in is never a good idea and will result in 'popping' on the overrun when decelerating with the throttle closed. Normally, 'spitting back' is due to a weak mixture at least in engines using conventional carburettors.
    2006 F650GS in Black
    9,300 Miles


Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •