Author Topic: Pops and Crackles  (Read 7506 times)

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Martz64

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on: April 18, 2021, 01:33:05 pm
I'm an absolute noob at, well, most thinks motorcycle...

Having replaced with the stock end cans with Scorpion Red Power pipes, I've noticed, to my delight, lots of pops and crackles on the overrun (especially with the the baffles out).

Is this indicative of leaks in the exhaust system, or should I just, you know, put up with it  :) ;) :P 


greentrumpet

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Reply #1 on: April 18, 2021, 02:41:00 pm
These lean-burn engines can pop a bit but if you put your hand near the joint between the silencer and the pipe you should to be able to feel gas leakage. As they say on the coffee cup, "caution, contents may be hot!"


dp3131

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Reply #2 on: April 18, 2021, 04:13:43 pm
i put red rooster pipes on mine and i had the same issue sometimes.  i was running 92 octane fuel and i read somewhere that using a lower octane lessens it.  so i use 87 octane now and it is a noticeable difference.  shrug


olhogrider

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Reply #3 on: April 18, 2021, 04:34:22 pm
It's a feature, not a bug.


Karl Fenn

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Reply #4 on: April 18, 2021, 04:46:21 pm
There is nothing you can do none stock cans do bang and pop nothing to do with air leaks just the fact they are none stock and not designed as stock. First thing is many do not have cats so the ECU is unable to figure out or control the mixture.
« Last Edit: April 18, 2021, 04:49:46 pm by Karl Fenn »


CPJS

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Reply #5 on: April 18, 2021, 05:06:57 pm
On mine I have the stinger 2-1 and a booster plug, no pops or bangs at all.
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Steve Palmer

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Reply #6 on: April 18, 2021, 05:17:48 pm
It's got nothing to do with the cats,the ECU controls the mixture through the lambda sensors.


GravyDavy

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Reply #7 on: April 18, 2021, 06:05:47 pm
It's got nothing to do with the cats,the ECU controls the mixture through the lambda sensors.
Yep, and the sensors are upstream of the cats.


Karl Fenn

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Reply #8 on: April 18, 2021, 06:48:31 pm
The cats actually controll the back pressure in the exhaust point of fact study how they work. The sensors are under backpressure this is measured by the ECU and mixture contoroled, if you create a higher velocity the sensors won't work as designed.
« Last Edit: April 18, 2021, 07:09:45 pm by Karl Fenn »


olhogrider

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Reply #9 on: April 19, 2021, 12:05:23 am
The cats actually controll the back pressure in the exhaust point of fact study how they work. The sensors are under backpressure this is measured by the ECU and mixture contoroled, if you create a higher velocity the sensors won't work as designed.
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viczena

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Reply #10 on: April 19, 2021, 07:38:06 am
Nope, he is right. In that it is a problem of backpressure in the exhaust.

An open exhaust pulls back fresh air into the exhaust, where there is leftover fuel, which ignites and bangs. Not good. Also because the lack of vacuum you get less torque in lower rpm. Also the lambda sensor gets false readings with the fresh air from the outside. It switches the EFI to lean the mixture.

The Cat is quite ideal for this purpose, it has realtively low resistance for the hot gas leaving the cylinder, but creates a lot of turbulence for the air that is sucked back into the exhaust. So if it was not already invented, it would be a fine (and expensive) device for tuning open exhausts. A ceramic insert for open exhausts with optimized floating design and platinum coated.

To get rid of the bang in the exhaust you should either lower or enhance the AFR in low rpm range, where the machine pushes. Enhancing AFR works much better.
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Breezin

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Reply #11 on: April 19, 2021, 09:19:50 am
The stock pipes pop and crackle on the overrun  once the engine is fully heated,  which takes some time.


viczena

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Reply #12 on: April 19, 2021, 09:33:49 am
The right solution would be to enrich the gas mixture, until it is too high to combust. That is against regulations. The other way, enlean the mixtur until it is too lean to combust does not really work all the time.

The ECU does have its own map for this effect.
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TrianglePete

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Reply #13 on: April 19, 2021, 10:39:10 am
It's a feature, not a bug.

  The deceleration POP saved my life twice in Houston,TX and Springfield, Mass 

In high speed traffic the POP wakes them up..


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Reply #14 on: April 19, 2021, 10:46:46 am
i put red rooster pipes on mine and i had the same issue sometimes.  i was running 92 octane fuel and i read somewhere that using a lower octane lessens it.  so i use 87 octane now and it is a noticeable difference.  shrug
    I agree why put expensive 92 octane gas in your bike when it's not really needed.  The resistance to

burn creates what is called endgas in the combustion chamber , that goes out and re-ignites  POP POP POP