Over run burble

[mudcow007]

Noticed this morning, when i sometimes come off the throttle on my bike it makes a lovely pop, bang burble..

What causes this?

It doesnt happen all the time, its normally slowing down after going fast-ish

is it unburnt fuel or something?

[Hahadumball]

its just the excess coolness working its way out.
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Fin: no matter how much I look at It I can't understand what was going through my head, all I remember is going about 80 and redlining it to stop it seizing.
360 Deg... Five 1/4 turns. :- Teflon-Mike 18 Jan 2015

[rubyhorse2]

my last superduke did this, absolutely loved it.

i presume its excess fuel being burnt off but sure someone with more knowledge will be here soon.

[Matt B]

Yes, it's just unburnt fuel igniting inside a hot exhaust. If you watch BSB or WSBK you've probably seen flames shooting out on the overrun. You should hear the 1200 Bandit with a stubby on.
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stinkwheel: He had an animated .gif of a cat performing fellatio. It's not socially acceptable. It can have real life adverse effects on other people.

[P.addy]

Absolutely love the bangs and pops from the triple, open cans and close throttle at 8k rpm... popopopopopbumbumbumbumbum

[wots]

My ER6 started it doing it on the stock can, discovered an exhaust leak, stopped doing it once I fixed that. If it's just started and you are on a stock can, or nothing aggressive (as above), might be worth checking.
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Currently: Yamaha DT 125 LC2,Repsol Fireblade, and Bumblebee MSX 125

[doggone]

[inline4]

My Bandit does this on closing the throttle and it has Beowulf end can.

However... and maybe someone can explain this one... the Blackbird does not do this and it has a full akra exhaust (so no catalytic converter) with pc3 and o2 eliminator installed.

[mudcow007]

This is on my Bandit 6 with a scorpion can on, im not gonna lie i think it sounds awesome...

[RhynoCZ]

The CB-1 I had, was equipped with the factory fitted exhaust system. It was not burping, it just accumulated enough fuel in the system and then made only one very loud bang with a lot of flame coming out of the can. It kind of sounded like a rifle shot. Those were the days...
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'87 Honda XBR 500, '96 Kawasaki ZX7R P1, '90 Honda CB-1, '88 Kawasaki GPz550, MZ 150 ETZ
'95 Mercedes-Benz w202 C200 CGI, '98 Mercedes-Benz w210 E200 Kompressor

[Rogerborg]

My Enfield has now shot 2 baffles out of the back of its exhaust. The third one is holding for now, but I feel that it's physically rejecting them.

The Tractor was ever so efficiently subdued, so I bought a damaged end can, hacked half of it out and now it's got a roguish growl and gurgle. I'm mullering the fuelling though, it feels down on torque at low revs. Fourth Reich First world problems.
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Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike

[Evil Hans]

[Jmh600]

[dydey90]

[.Bishbash.]

Like this?

Love my stubby on the bike. But yes, as mentioned above, it's unburnt fuel basically exploding in your pipe.
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Current bike - GSX-R1000 k8

[Pigeon]

My SV
https://youtu.be/6fHE1yNk0js?t=42

Striple more like
https://youtu.be/9lVvgc45Y4w?t=604
https://youtu.be/9lVvgc45Y4w?t=411


https://youtu.be/YJ6FCvEBfrs?t=19

[craigs23]

Grom + free flowing exhaust + multistory car park =

Vtec superfour and Gullarm stubbies provide a few nice thwaps on the overrun too...

[trevor saxe-coburg-gotha]

It's running lean.
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"Life is a sexually transmitted disease and the mortality rate is one hundred percent."

Mobylette Type 50 ---> Raleigh Grifter ---> Neval Minsk 125

[Dave V4]

[Vracktal]

My BMW with the straight pipe from the cat backwards makes a decent rumble on the overrun. Need to shoot video of it at some point to see if it shoots flames or anything cool though.


The KLE just does whatever the fuck this is
https://www.youtube.com/watch?v=sY2Yrx1Qgp0
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2007 BMW R1200R: On road
2009 BMW G650X Challenge: On road
1975 Norton Commando 850: Off road, awaiting recommissioning

[ScaredyCat]

[M.C]

MT-03 does this all day long (with the stock can). Could explain the rather poor fuel economy

[Ariel Badger]

People have learned not to get too close to the back of my bike in holding, she can spit a three foot flame if she is angry.
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Bikers make great organ donors, get 115 on your licence today.

[.Bishbash.]

[stevo as b4]

EFI bikes and overrun fuel cut off though? Surely in todays age of manufacturers and legislation obsessed in getting some decent mpg out of big bikes and performance engines to the point that it ruins the throttle response and drivability, they use this feature too?

I know early EFI bikes and anything pre-cat would have had the fueling strategy of basically being an electronic carb and if it doubt give it a another spray of fuel just to make sure its gulping it all the time, but in 2015, I'm surprised that many newer bikes even with loud pipes are spitting and banging like a VTR1000 with microns and a DJ kit.

I quite like my quiet refined little 2strokes these days, so banging and flames does not seem too important or cool. Will be happier too when I get the car mapped on an ECU that does not drown it, so that it too stops making flames after a boot full on the ring road.