What makes the exhaust crack and pop on the over-run..?

MrFell

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My 2013 LC ownership started life in standard form.
It then went to Hilltop for the re-map. On down shifts there occasionally would be a nice burble and crackle. Nothing offensive but quite pleasing to the ear.
I've now fitted a set of de-cat headers but kept the standard end can.
Now there is a pleasing lower, but not much louder, tone and bark on hard acceleration.
The bit i'm slighly confused over is that the crackle and pop on the over run has disappeared almost completely..!

I would love to know how / why this has happened..?

Thanks for any explainations.....
 
Better fueling? My 2014 pops and crackles on the over run especially on a closed throttle in 2nd and 1st gear.
 
I like the pop/burble on the overrun and when you change up rapidly when accelerating hard. Hilltop change the fuelling so not surprised it changes the way it sounds - try asking them for an explanation.
 
I am no expert but I always understood it to be unburnt fuel igniting in the exhaust. Sometimes it needs a bit of an air leak to get it to ignite as there's not much oxygen in the exhaust otherwise.

No doubt someone who knows what they are talking about will explain properly.
 
It's the added 'fun' chip.

The sound is worth the tenner's worth of fuel it might use over a couple of years, so don't feck with it, just enjoy it :thumb2
 
It's bad when it blows the throttle body out!!

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On my old 500/4 I had a 4 into 1 with a straight through Gold Star tail pipe fitted.

I used to have fun in town killing the ignition on over run and opening the throttle at the same time, this used to fill the exhaust with fuel. It used to sound like a 120mm Howitzer (big gun to you kids) going off when the kill switch was turned back on :D :D
 
Outtomunch said:
My old ( highly tuned) Guzzi outfit would regularly blow one of the carbs off the inlet rubbers when starting her :D

Andres
Click to expand...
My old (badly tuned) Guzzi Convert would regularly bang like a gunshot and spit a cloud of smoke under the tank from the foam air filters. Then start nice as ninepence second press of the button, while the neighbours looked around for the culprit.
 
AFAIK Spitting back in the carbs/injector is a different cause. A very lean mix will cause spit back - lots of little spits (dunno why but it does) and a big explosive spit back on a failed start is as the engine rocks back off tdc, the inlet valve opens and the compressed mixture spits out through the inlet manifold and could be quite powerful, certainly enough to blow a badly mounted carb or injector of its mount.
 
Happened to my 2007 R1200GSA a few months ago.

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Paul G (BHT) said:
On my old 500/4 I had a 4 into 1 with a straight through Gold Star tail pipe fitted.

I used to have fun in town killing the ignition on over run and opening the throttle at the same time, this used to fill the exhaust with fuel. It used to sound like a 120mm Howitzer (big gun to you kids) going off when the kill switch was turned back on :D :D
Click to expand...
Used to do similar in SA when driving police vehicles
Population floored...

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It just seemed odd to me that fitting the de-cat headers has removed the popping and banging on the over run....
From my limited / lack of knowledge, i assumed it would have created more.

Still thanks for the comments
 
MrFell said:
It just seemed odd to me that fitting the de-cat headers has removed the popping and banging on the over run....
From my limited / lack of knowledge, i assumed it would have created more.

Still thanks for the comments
Click to expand...

The new system is probably sealed up better so no air leaks, or isn't sucking any fuel mix into the pipes for it to ignite.
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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