Surge in RPM's when idle..... - K-Bikes.com - Excellence in Motion
 
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post #1 of 9 (permalink) Old Nov 29th, 2005, 7:30 pm Thread Starter
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Cool Surge in RPM's when idle.....

Hey all,

Awhile back I posted about a problem I was having with my 03 GT.

On a recent trip back from Florida, I began to experience what I can only describe as surging of the bike - which I (apparently) incorrectly thought was due to low fuel in the tank.

Anyway, over the period of a week, I experienced a problem in which the bike would surge in RPMs from around 1000-3000 rpms very erratically. I've pretty much not been able to nail down any coherent set of events that correlate between the incidents. Speed, temperature, gas level all appear to not matter.

I've had the surging happen at slow speeds or at a stop. On an empty tank or a full tank. Warm or cold. I can't seem to recall if it's happened when the bike is cold, but it's happened frequently when on 30-40 min+ rides.

On the way home from Florida, I put in some Techron to clean the injectors, ran different grades of fuel (from 89 to 93), etc. It seemed to clear things up..... And then.....

Last week, the dealer checked out the bike, and changed the fuel filter. They couldn't replicate the problem (and to be honest - I hadn't had that problem either).

Today, I was riding home from work. Conditions - 35 degrees, ~50 miles on the tank, ~50 mile ride. I pulled off the exit ramp, had the clutch lever pulled in, bike was in 1st gear. It started to surge from idle to 2000 rpms. Bike didn't stall, but the light changed before I could check. I got home (about ~2 miles away), and it idled fine.

Any ideas as to what might possibly be at issue here? The bike runs fine at speed and I'm slightly annoyed at this erratic problem.

alow

2003 BMW K1200GT (Orient Blue) (Fast)
1982 Honda MB5 (Not So Fast)
IBA #22048

"This motorcycle is simply too goddamn fast to ride at speed in any kind of normal road traffic unless you're ready to go straight down the centerline with your nuts on fire and a silent scream in your throat."
- Hunter S. Thompson
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post #2 of 9 (permalink) Old Nov 29th, 2005, 8:03 pm
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I am no mechanic what so ever but thought I would share this with you. My GT was rising and dropping RPM's while at idle,mechanic at my shop found a vaccum line had came loose,stuck it back on and it has idled perfectly ever since.

Enjoying The Ride. Eddie Layton
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post #3 of 9 (permalink) Old Nov 30th, 2005, 8:55 am Thread Starter
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edlk1200,

Do you happen to know where this vacuum line is? Is it easily accessible if I were say, standing in the parking lot this morning cursing at my bike b/c it was idling so poorly it stalled out at 2 traffic lights?

Thanks!
alow

2003 BMW K1200GT (Orient Blue) (Fast)
1982 Honda MB5 (Not So Fast)
IBA #22048

"This motorcycle is simply too goddamn fast to ride at speed in any kind of normal road traffic unless you're ready to go straight down the centerline with your nuts on fire and a silent scream in your throat."
- Hunter S. Thompson
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post #4 of 9 (permalink) Old Nov 30th, 2005, 9:34 am
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I'm not sure your problem is the vacumn lines. Mine was shipped with 2 vacumn lines that connect to the throttle bodies unhooked because they were cut too short. The bike would idle very fast but not do a lot of surging. After I got new lines and hooked them up the idle speed dropped down to where it was supposed to be. Still doesn't have an absolutely constant idle speed.
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post #5 of 9 (permalink) Old Nov 30th, 2005, 11:16 am
 
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Quote:
Originally Posted by alowishus
edlk1200,

Do you happen to know where this vacuum line is? Is it easily accessible if I were say, standing in the parking lot this morning cursing at my bike b/c it was idling so poorly it stalled out at 2 traffic lights?

Thanks!
alow
alow,

Do you have a new ECU?
The vacuum line is behind the left fairing, which will require removal for its inspection. There have been a couple pictures posted to the threads, you might want to search a little. There might be a couple pics from the old forum archieves. While the fairing is off, check to see if the there is enough play in the cruise control line. I have heard this gets pinched sometimes that may lead to an erratic idle.

There are other similar posts that touch on this issue in the archieves, check them out a little. Here are a quick few that might help.

http://www.k-bikes.com/ubbthreads/sh...w=&sb=&o=&vc=1

http://www.k-bikes.com/ubbthreads/sh...w=&sb=&o=&vc=1


ONON-
Mark
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post #6 of 9 (permalink) Old Nov 30th, 2005, 2:25 pm
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Yes the vacuum line was behind the left farring,it attaches at the side of the engine.

Enjoying The Ride. Eddie Layton
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post #7 of 9 (permalink) Old Nov 30th, 2005, 7:26 pm Thread Starter
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Quick update:

I took it back to the dealer this afternoon and they agreed to check it over again. I'm not sure about the vacuum problem, since I was informed that if it were a vacuum problem, it would be pretty much a constant problem (which this is not).

The current theory is that the ECU (when replaced several monthes back) was not seated properly, or one of the pins is not proprely seated). Whatever the problem, the dealership has agreed to keep the bike and check it over again......

alow

2003 BMW K1200GT (Orient Blue) (Fast)
1982 Honda MB5 (Not So Fast)
IBA #22048

"This motorcycle is simply too goddamn fast to ride at speed in any kind of normal road traffic unless you're ready to go straight down the centerline with your nuts on fire and a silent scream in your throat."
- Hunter S. Thompson
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post #8 of 9 (permalink) Old Dec 2nd, 2005, 6:59 am Thread Starter
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Hi all,

Just a quick update.....

I picked up my bike this morning (18 degrees - it's cold out??).....

Service manager told me that 3 of the 4 vacuum hoses were either off or had cracks in the hoses in some fashion. Since I'm not really sure how these connect up, I don't know why it wouldn't be aconstant problem (vs. the intermitent one I was having). He explained how it would be intermitent but not having a point of reference I'll take his word for it.

Anyway, they replaced all 4 (I think there are 4 total). Seems like it ran alot better on the short ride home. Guess I'll find out more when I take 'er out again.

See ya!
alow

p.s. They checked the ECU and it was seated properly......

2003 BMW K1200GT (Orient Blue) (Fast)
1982 Honda MB5 (Not So Fast)
IBA #22048

"This motorcycle is simply too goddamn fast to ride at speed in any kind of normal road traffic unless you're ready to go straight down the centerline with your nuts on fire and a silent scream in your throat."
- Hunter S. Thompson
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post #9 of 9 (permalink) Old Dec 2nd, 2005, 12:53 pm
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I would bet you'll be O.K. now, mine has idled perfectly after the fix.Let us know.

Enjoying The Ride. Eddie Layton
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