I ride a Harley Davidson Road King, I noticed last weekend when I was riding down Sutton Bank on my way home from the Farmyard that I was hearing some fairly loud back firing from the exhausts .  I was in a low gear for the gradient of the hill, not sure if this is normal or if there is something wrong ?  Can anyone help with advice please.    Many thanks in advance                                                                                                                                                                              

All my last 9 bikes (ducati's)
Have done this, AFTER I fitted "after Market"
Systems (exhaust/ecu chip)

Think maybe twins prone to it?
Happens more on over-run though?
(when been going faster, then shutting throttle
Off completely?)

It great isn't it he he :-))

I don't think you have a serious problem there BK   It sounds like unburned fuel igniting in the exhaust on the "over-run"   Which can happen in prolonged deceleration   As you were on Sutton Bank that is a very likely place for it to show up   I assume that this was a "rare" event (backfiring) for you and your bike   If its not doing when you "shut off" normally I wouldn't worry   But there are plenty of HD "experts" on here so I may be proved wrong                                                                                                                                                                             

Exactly wot emzed sed   you'll hear it mainly when sports bikes are shutting off for cornirs and coming down the box when engine is on over run. just build up of fuel in chamber. if exhaust was short enough you'd get flames as well. now there's an idea.                                                                                                                                                                              

As above (bluesbiker)
That's my fav way of "discouraging"
Boy (or girl) racers, driving too close in slow
Moving tragic (in town)
Even better in a tunnel with a big twin,
Am sure this is why I keep melting the
Right side of my number- plate and indicator
:-))

I get feckin great flames coming out of my pipes if I try really hard                                                                                                                                                                              

me too jp but don't have to try too hard just shut off and open throttle a little will pop and bang and may get flames my mazda also spits flames                                                                                                                                                                             

Is it the rotary engined Mazda apriliamad    Rotary engines are well known for serious over-run detonations as they only really like to rev,  not slow down     I've seen the "factory" Norton's shooting a foot or more of flames out the back   Sure made the following riders "back off" into the hairpin                                                                                                                                                                              

yes emzed rotary lump no cat and straight though system in stainless                                                                                                                                                                             

Wicked mate      Trust a biker to go for sumat "out the ordinary"   I'd love to put that lump in an outfit    I think rear tyres might not last very long    But it would be great fun while they lasted     Sorry BK for "hijacking" your thread                                                                                                                                                                                 

does sound like overrun...my kwak does it and all.....great fun!
                                                                                                                                                                             

A few Raptor and TL 1000 owners have known this.  If it's not a normal part of the bike's running, it may be a leaky exhaust gasket/joint.                                                                                                                                                                             

I get it too Katie on overrun, minus the flames! lol                                                                                                                                                                             

There you have it BK   In a "nutshell" if it's only happened the once (or very rarely)   Then in all probability it's what I said in the earlier post   Unburnt fuel igniting in the exhaust   As Wierdoraptor says though, you can get similar symptoms   (If it is happening on a regular basis)   When you have a "leaky" exhaust system which will draw air in on the "overrun" (There are a few "technical" explanations for this phenomena, but you don't need to know them)   So "I" don't think you need to worry   Hope this helps to put your mind at rest                                                                                                                                                                             

Thank you all very much for your advice, my mind is at ease - it's all a big learning curve.                                                                                                                                                                              

Hi Bobkat, My T100 Bonnie does it as well, it's got aftermarket pipes on and it sounds "Magnificent" yar.
I agree with all that has been siad, unburnt fuel in the exhaust system, absolutely correct!
Mark
Possum51181
                                                                                                                                                                             

my sportster does it too on deceleration sometimes, i love it - i thought maybe it was due to "leaky" exhaust system bt from reading above i guess it would do it all time if this was case.   which pipes have you got on your beastie BK?  xx                                                                                                                                                                              

Unburnt fuel in the exhaust system shouldn't be normal - it might sound good occassionaly - but I'd be checking other things with suspicion. Could be a weak ignition coil, lead or plug , if it happens at start up?