contradicting lean or rich
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Intermediate
Joined: Apr 2008
Posts: 36
Likes: 0
From: High River Alberta
contradicting lean or rich
Ok i have an 08 street bob... seems like its running lean.. however some evidence is contradicting... black deposits inside pipes... but im getting surging at low speeds... pulled the plugs... and again its contradicting... black deposits on thread... some tan color on the white area... and again on the curved top piece... pictures comming.. charging batteries for camera... anyone have ideas... oh i checked the gap.. its within 38-43
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Intermediate
Joined: Apr 2008
Posts: 36
Likes: 0
From: High River Alberta
RE: contradicting lean or rich
ORIGINAL: Punty
It might help to have more info, Isthe bikeStock? Either way the Inside of any pipe will have Soot.
It might help to have more info, Isthe bikeStock? Either way the Inside of any pipe will have Soot.
*Edit* I do only have 700 miles on the skoot atm
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Intermediate
Joined: Apr 2008
Posts: 36
Likes: 0
From: High River Alberta
RE: contradicting lean or rich
ORIGINAL: BONES206
A couple of questions. Why do you feel its running lean?
Is the surging under acceleration or at cruise?
A couple of questions. Why do you feel its running lean?
Is the surging under acceleration or at cruise?
Novice
Joined: Oct 2007
Posts: 24
Likes: 0
RE: contradicting lean or rich
ORIGINAL: Enviros
Ok i have an 08 street bob... seems like its running lean.. however some evidence is contradicting... black deposits inside pipes... but im getting surging at low speeds... ...
Ok i have an 08 street bob... seems like its running lean.. however some evidence is contradicting... black deposits inside pipes... but im getting surging at low speeds... ...
You can have a rich&lean condition at (almost) the same time. You will notice this as a "surge" at constant throttle.
One thing that can cause the "surge" is the closed loop fuel injection system. When the O2 sensor reads RICH, the computer controlling the FI delivers LESS fuel to the engine in order to return the system to the correct the air:fuel ratio. BUT, with less fuel delivered to the engine, the O2 sensor now reads LEAN and sends a message to the computer to deliver MORE fuel to the engine. Then .... (repeat ad infinitum).
The tangible effect of rich/lean/rich/lean .... is a "surge" as the computer works (hunts) to adjust the mix.
To adjust for your intake and exhaust mods, has the bike's computer been flashed to modify the ignition/fuel parameters or are you running a HD or aftermarket module that adjusts the ignition/fuel?
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Road Master
Joined: Jan 2006
Posts: 1,154
Likes: 3
From: Colorado Springs
RE: contradicting lean or rich
ORIGINAL: 84FXRP
You can have a rich&lean condition at (almost) the same time. You will notice this as a "surge" at constant throttle.
One thing that can cause the "surge" is the closed loop fuel injection system. When the O2 sensor reads RICH, the computer controlling the FI delivers LESS fuel to the engine in order to return the system to the correct the air:fuel ratio. BUT, with less fuel delivered to the engine, the O2 sensor now reads LEAN and sends a message to the computer to deliver MORE fuel to the engine. Then .... (repeat ad infinitum).
The tangible effect of rich/lean/rich/lean .... is a "surge" as the computer works (hunts) to adjust the mix.
To adjust for your intake and exhaust mods, has the bike's computer been flashed to modify the ignition/fuel parameters or are you running a HD or aftermarket module that adjusts the ignition/fuel?
ORIGINAL: Enviros
Ok i have an 08 street bob... seems like its running lean.. however some evidence is contradicting... black deposits inside pipes... but im getting surging at low speeds... ...
Ok i have an 08 street bob... seems like its running lean.. however some evidence is contradicting... black deposits inside pipes... but im getting surging at low speeds... ...
You can have a rich&lean condition at (almost) the same time. You will notice this as a "surge" at constant throttle.
One thing that can cause the "surge" is the closed loop fuel injection system. When the O2 sensor reads RICH, the computer controlling the FI delivers LESS fuel to the engine in order to return the system to the correct the air:fuel ratio. BUT, with less fuel delivered to the engine, the O2 sensor now reads LEAN and sends a message to the computer to deliver MORE fuel to the engine. Then .... (repeat ad infinitum).
The tangible effect of rich/lean/rich/lean .... is a "surge" as the computer works (hunts) to adjust the mix.
To adjust for your intake and exhaust mods, has the bike's computer been flashed to modify the ignition/fuel parameters or are you running a HD or aftermarket module that adjusts the ignition/fuel?
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Cruiser
Joined: Sep 2007
Posts: 194
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From:
RE: contradicting lean or rich
If you have installed a PCIII, the rich/lean/rich/lean theory doesn't hold water since the Powercommander eliminates the O2 sensors. If you have a surge at small, steady throttle openings - it usually indicates lean running. Checking plugs later can be a bit misleading, unless you were to run the bike for a period in the predicted lean mode, shut the bike off and coast to a stop (at least that was the trick in the old days to get a more accurate read from the color of the plugs.) Just my .02.
Tourer
Joined: Dec 2006
Posts: 314
Likes: 0
From: North Hills California
RE: contradicting lean or rich
A lean condition can sometimes be mistaken for a rich condition since because an overly lean mixture will not completely ignite. Mine does the same thing in closed loop mode, but I think its due to overlap on the longer duration cams. Timing / lean mixture could be the culprit here, but it would be hard to nail down without a dyno tune, or some form of data logging device. Next time you get a chance, pull the dipstick, and see if the oil smells like gas.