Popping! - MVAgusta.net
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post #1 of 12 (permalink) Old 04-11-2007, 03:23 AM Thread Starter
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Exclamation Popping!

Just wondering if the 'popping' when off the throttle is a norm.
It is probably due to a rich mix,as the bike is only 890km old and may disappear after first service.
Throttle bodies are checked and spark plugs also.
Has anyone got this?Has it stopped at service?
Minor I know,but its always good to know for sure.

07 F41000R
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post #2 of 12 (permalink) Old 04-11-2007, 04:02 AM
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My S does this (Rg3's and chip), but not when standard. Mine is not bad but I have been told a bit of tuning at my next service in a couple of weeks will fix it.

MVA Sydney
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post #3 of 12 (permalink) Old 04-11-2007, 07:05 AM
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my brute started to do this just prior to first service but that rectified it..
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post #4 of 12 (permalink) Old 04-11-2007, 07:42 AM
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It's actually what happened when my bike was leaned out (a lot) when I had the PC-III installed. It may be worth having one fitted...

When a passenger of the foot moves in sight, tootle the horn trumpet melodiously to him at first. If he still obstacles your passage, tootle him with vigor and express by word of mouth the warning, "Hi, hi."

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post #5 of 12 (permalink) Old 04-11-2007, 08:08 AM
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It is actually caused by a lean condition when the throttle is off.
Proper CO setup can help, but with a PC, the tuner has to know where to add fuel to eliminate this common sympton.

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post #6 of 12 (permalink) Old 04-11-2007, 10:16 AM
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Quote:
Originally Posted by airfuel
It is actually caused by a lean condition when the throttle is off.
Proper CO setup can help, but with a PC, the tuner has to know where to add fuel to eliminate this common sympton.
Lean??? I usually equate this with a somewhat rich mixture. In the old days of carburetors, closing the throttle resulted in high intake manifold vacuum. The high vacuum signal would pull excess fuel through the metering passages and the mixture would go rich.

Unburned, super heated hydrocarbon would enter the exhaust where it comes into contact with free oxygen. The super heated hydrocarbon immediately ignites resulting a "popping" combustion in the exhaust pipe. This was common on almost all race engines - sometimes you would see flames coming out of the exhaust.

Modern fuel injection has done away with a lot of this, but it still occurs. My 910R does it - even more so since I put the "race" exhaust and chip in. My CO is ~4%.

In my experience, lean mixtures result in backfiring through the intake (especially when opening the throttle). I'm always willing to learn, if a lean mixture causes the exhaust to pop on deceleration I'd like to know how and why.

Mike

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post #7 of 12 (permalink) Old 04-11-2007, 12:04 PM
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sometimes you would see flames coming out of the exhaust.



i like that!
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post #8 of 12 (permalink) Old 04-11-2007, 03:10 PM
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i just got my F4 and have about 150 miles on it and it pops too. It also load up in 2nd gear under heavy throttle. But i'm back in iraq so i will have to fix it when i get home.
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post #9 of 12 (permalink) Old 04-11-2007, 03:15 PM
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Quote:
Originally Posted by airfuel
It is actually caused by a lean condition when the throttle is off.
Proper CO setup can help, but with a PC, the tuner has to know where to add fuel to eliminate this common sympton.
Airfuel, my experience with my bike seems to be similar to Koop.

My bike dumps a lot of raw fuel through it at idle, and I'm guessing it's partially doing the same thing at closed throttle on downshifts.

I can physically feel an explosion (that I'm half worried will damage my exhaust) in my seat when I get back on the throttle. People tell me the thing shoots a flame a few feet out of the exhaust.

So, lean or rich?

Oh, it got worse when I put in a WCT chip, which fixed the on/off throttle transition in corners. I assume it richened the mixture at that point a little bit.

'01 F4S
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post #10 of 12 (permalink) Old 04-11-2007, 03:22 PM
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Backfireing is different from decel popping. Random bangs like a shotgun is excess fuel pooling then hitting something that ignites it. (carb days)
Decel popping is that little consistant rumbling you get when off the gas. Lean will cause incomplete combustion and small amount s of fuel will either ignite when it hits the hot exhaust pipe wall or fresh air at the end of the exhaust tip.

With bikes that decel pop, giving the pc some gas at the zero column will help lessen the decel popping.

John T
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