Surging Where to begin?
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Road Captain
Joined: Aug 2012
Posts: 579
Likes: 38
From: Texas
Surging Where to begin?
I will try to be brief but lots of mods and changes so I do not know where to begin trying to track this down.
This weekend we made a run from Houston to New Orleans. Outside temps about 90 degrees and average speeds around 80-85 MPH.
I had me and momma on the bike with our gear. The bike is surging under 1/2 to 3/4 throttle over 2500RPM. I have not noticed it doing this when running solo. I will try tomorrow and see if it is the same.
In the last couple of months I have Swapped rear wheel so I had to reset belt deflection, I have replaced the compensator and added a Hayden tensioner, I have had the bike dyno tuned for A/C, Pipes, headers etc....Of Course I had it done at a rally so the tuner is not local.
One thing I did notice in my slip on, Pass side (rear cylinder) is discoloring. Maybe a lean condition?
At wide open throttle it pulls great with no indication of surge. Only at partial throttle over half throttle.
Thoughts?
This weekend we made a run from Houston to New Orleans. Outside temps about 90 degrees and average speeds around 80-85 MPH.
I had me and momma on the bike with our gear. The bike is surging under 1/2 to 3/4 throttle over 2500RPM. I have not noticed it doing this when running solo. I will try tomorrow and see if it is the same.
In the last couple of months I have Swapped rear wheel so I had to reset belt deflection, I have replaced the compensator and added a Hayden tensioner, I have had the bike dyno tuned for A/C, Pipes, headers etc....Of Course I had it done at a rally so the tuner is not local.
One thing I did notice in my slip on, Pass side (rear cylinder) is discoloring. Maybe a lean condition?
At wide open throttle it pulls great with no indication of surge. Only at partial throttle over half throttle.
Thoughts?
Extreme HDF Member
Joined: Sep 2010
Posts: 14,744
Likes: 402
From: Phoenix '53, '88, '09 Big Twins
any codes?
I'd be looking at the mass air flow sensor (edit: sorry, Temperature Manifold Absolute Pressure: TMAP) which is used to calculate air density.
if it were dirty or had a bad o ring, thus giving bad info to the ECM....then the o2 sensors would tell the ecm something ain't right...then it is constantly hunting all over the place.
if you have a piggyback tuner, disconnect, and reconnect to clean the connections.
clean the connection for the servo motor.
those are the first steps I;'d take
mike
I'd be looking at the mass air flow sensor (edit: sorry, Temperature Manifold Absolute Pressure: TMAP) which is used to calculate air density.
if it were dirty or had a bad o ring, thus giving bad info to the ECM....then the o2 sensors would tell the ecm something ain't right...then it is constantly hunting all over the place.
if you have a piggyback tuner, disconnect, and reconnect to clean the connections.
clean the connection for the servo motor.
those are the first steps I;'d take
mike
Last edited by mkguitar; Jun 23, 2014 at 12:39 PM. Reason: time travel- TMAP
Ultimate HDF Member
Joined: May 2008
Posts: 7,439
Likes: 884
From: 'Noke, VA
Uhhh, unless your bike is from the future, you don't have a Mass Airflow Sensor.
Start with the usual suspects. Plugs, wires, fuel filter. Possibly a pinhole in the in-tank fuel line. If you've got a piggyback tuner, remove it and plug the O2 sensors back in.
Start with the usual suspects. Plugs, wires, fuel filter. Possibly a pinhole in the in-tank fuel line. If you've got a piggyback tuner, remove it and plug the O2 sensors back in.
Seasoned HDF Member
Joined: Jan 2006
Posts: 11,463
Likes: 2,990
From: Charleston, SC
It does however have a MAP sensor which is nearly the same thing.
As mkguitar suggested, try cleaning the map sensor, and check for intake leaks. It is most likely an intake leak...
But a whole number of things can cause actual surging or the sensation of surging. One being an overly tight or overly loose primary chain.
lp
As mkguitar suggested, try cleaning the map sensor, and check for intake leaks. It is most likely an intake leak...
But a whole number of things can cause actual surging or the sensation of surging. One being an overly tight or overly loose primary chain.
lp
Last edited by lp; Jun 23, 2014 at 05:51 AM.
Thread Starter
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Road Captain
Joined: Aug 2012
Posts: 579
Likes: 38
From: Texas
Thank you for the suggestions so far. I will try cleaning everything up and go from there. I have the Big Sucker with the crank case vents so I plan on pulling it apart to vent anyways. I have been getting a lot of oil on the cam chest.
I have had the Hayden on for about 1500 miles so I am interested to see how its doing. I may pull the primary and check it also.
I have had the Hayden on for about 1500 miles so I am interested to see how its doing. I may pull the primary and check it also.
Outstanding HDF Member
Joined: May 2008
Posts: 2,543
Likes: 19
From: Ashland Ohio
Hahahaha. A MAP sensor is NOT near the same thing as a MAF sensor. I got that dude misspoke, like I do. Look under the hood of any car, on the intake coming from the air filter... big rubber tube and in that tube is wires. THAT is the MAF, it usually has a platinum wire or grid inside that heats up, this measures the amount of AIR entering the engine by seeing how much electricity it takes to keep it heated. I WISH our bikes had a MAF. No more dicking with VE tables etc, and this measures the air entering the engine by the pound.
A MAP sensor is no more than a vacuum guage. It can tell the load placed upon the engine, but not ANYTHING about how much air the engine is using.
Not even close. Not 'nearly the same thing' at all.
I ended up running the Baker Attitude adjuster, but realize that is not for most folks.
A MAP sensor is no more than a vacuum guage. It can tell the load placed upon the engine, but not ANYTHING about how much air the engine is using.
Not even close. Not 'nearly the same thing' at all.
I ended up running the Baker Attitude adjuster, but realize that is not for most folks.
Last edited by wurk_truk; Jun 23, 2014 at 09:28 AM.
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Road Captain
Joined: Oct 2007
Posts: 634
Likes: 8
From: Plum & Nearly
first thing i would check is to make sure the rubber vacuum cap is still in place on the nipple that extends out the top of the throttle body. These come off often or split from age and heat and then are a direct source of air into the intake bypassing the throttle plate. This is un-metered air (just like an intake seal leak) and will cause surging. the part number for the rubber cap is 90383-98.
Last edited by twincam47; Jun 23, 2014 at 11:30 AM.
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Extreme HDF Member
Joined: Nov 2007
Posts: 14,670
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From: East of the Sun, West of the Moon
worst investment ever made to my ride. put the stocker back in after almost 2000+ miles and listening to that irritating sound not to mention the "clunk" caused with it installed.
To the OP:
what did they tune your bike with?
Seasoned HDF Member
Joined: Jan 2006
Posts: 11,463
Likes: 2,990
From: Charleston, SC
Hahahaha. A MAP sensor is NOT near the same thing as a MAF sensor. I got that dude misspoke, like I do. Look under the hood of any car, on the intake coming from the air filter... big rubber tube and in that tube is wires. THAT is the MAF, it usually has a platinum wire or grid inside that heats up, this measures the amount of AIR entering the engine by seeing how much electricity it takes to keep it heated. I WISH our bikes had a MAF. No more dicking with VE tables etc, and this measures the air entering the engine by the pound.
A MAP sensor is no more than a vacuum guage [And an Intake Air temp Sensor] . It can tell the load placed upon the engine, but not ANYTHING about how much air the engine is using.
Not even close. Not 'nearly the same thing' at all.
I ended up running the Baker Attitude adjuster, but realize that is not for most folks.
A MAP sensor is no more than a vacuum guage [And an Intake Air temp Sensor] . It can tell the load placed upon the engine, but not ANYTHING about how much air the engine is using.
Not even close. Not 'nearly the same thing' at all.
I ended up running the Baker Attitude adjuster, but realize that is not for most folks.
<sigh>Yes, they are technically different but that isn't the point is it.
A broken or out of range MAP or MAF is going to affect the fuel mixture or spark advance.
OP is looking for a reason his bike is surging.
Do you have any info on that subject?
That would be kinda cool - overly technical guy who owns a dyno....
lp
Last edited by lp; Jun 23, 2014 at 12:00 PM.