Welcome to Netrider ... Connecting Riders!

Interested in talking motorbikes with a terrific community of riders?
Signup (it's quick and free) to join the discussions and access the full suite of tools and information that Netrider has to offer.

Popping and flames

Discussion in 'Technical and Troubleshooting Torque' started by jessehall1987, Nov 27, 2014.

  1. hey guys iv googled this question and cant get a straight answer . I have a Hyosung gt650r when I roll off and bikes decelerating it pops and carrys on which hasn't worried me until tonight riding home from work I noticed everytime the exhaust pops while decelerating its spitting flames out of the exhaust ... is this bad for my bike??
    and please no comments on it being a shitty Hyosung please I know there crap but its the best I can afford at the moment

    • Like Like x 1
  2. My bet is aftermarket exhaust without adjusting fueling. Not ideal but unlikely to be a problem. If it worries you, stuff some steel wool in your exhaust.
  3. People pay to have their bike spit flames :)
  4. The popping noise is unburnt fuel in the exhaust igniting, it doesn't usually harm anything , but it will make people raise their eyebrows at you :)
    Check for loose bolts on the exhaust, you may have developed a leak.
  5. I'm assuming its a carbureted model? Its a common characteristic of V-Twins and high performance engines and to explain it you need to understand how a carburettor works.

    when an engine is idling and the throttle is closed fuel is supplied to the engine by the pilot system.

    when the throttle is closed at higher RPM there is a massive vacuum created in the intake system, this causes a higher rate of air flow through the throttle valve, and intern creating a very lean mixture of of air:fuel.

    This lean air:fuel mixture often cannot be burnt or is not burnt fully leaving the combustion chamber, and either accumulates in the exhaust until it is ignited "Popping" or comes out the exhaust as a jet of flames "Flaming".

    This is perfectly normal and even expected when an engine is tuned for best performance rather than fuel economy. It is also compounded where modifications to the exhaust system such as free-er flowing pipes are added and no modification to the carburettor is made to compensate.

    the issue is lessened on electron fuel injected engines where ECU's have deceleration maps that may completely cut fuelling on deceleration.

    It won't cause any harm however if it is due to a modded pipe and no rejecting of the carbs your bike may not be as fuel efficient as it could be, but we are talking cents per every tank fill not dollars, Hope that helps.
    • Winner Winner x 1
    • Informative Informative x 1
  6. Watch V8 Supercars as examples of mobile flamethrowers... (y)
  7. Popping on closing the throttle is usually indicative of lean mixture on the idle screws.
  8. This thread makes me miss my VTR1000....
    • Like Like x 3
  9. I like the sound of a flaming exhaust! Would be a great look at night...but a bit of a cop magnet I would guess?:troll:
  10. May just be normal but also could be indicative of incorrect mix, incorrect timing or leaking manifold.

    Also I think it is a bit unfair restricting comments against Hyos, some people just want to spoil all our fun.
  11. What Clint said - a mage that bloke....

    And damn.......I want a Firestorm
  12. Try blanking / blocking the exhaust Air Injection System.
  13. I'm not a fan of the steel wool packing in exhausts Fine steel wool is actually flammable and I would see this as compounding the fire risk in the country where you might be exuding, effectively, hot sparks. Flames are one thing, but sparks are quite another. Coarse steel wool maybe, but only in the Winter. Not a good Summer option.

    I agree that air injection systems contribute to popping. This is a reason many modern bikes have such large exhaust cans. Changing the original can to a lighter aftermarket one often makes this more noticeable and can lead the owner up the garden path of chasing air leaks, which they might actually have created in the new join.

    Removing (blocking) the air injection system if one exists is often effective to stop the pop.
  14. or stick in a spark arrestor exhaust insert... (like a fancy tea strainer)
  15. My vt does this too... i was a bit worried