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post #1 of 6 (permalink) Old Jun 20th, 2012, 6:21 am Thread Starter
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uneven idle

Hello,

Its been a while since I've been on here which means that things have been going pretty well with my bike (2000 K1200RS) and I've been doing a lot of miles, something like 16000 miles in the last year, she's been riding great, but recently there is an intermittent fault which is happening with increasing regularity.

Its that the idle rises and falls from around 850 rpm up to approx 1100 rpm, when I come to a stop and pull the clutch it has been known to surge up to 1800 or completely drop off and stall.

does anyone have any experience of this, or any suggestions?

Thanks in advance for the help

Richard
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post #2 of 6 (permalink) Old Jun 20th, 2012, 9:04 am
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Done a TPS reset recently? Ignition ON then open and release throttle all the way 3 times. Ignition OFF. Done.

Yes we may have other ideas but....try the easy things first.

Benelli 50cc at 14
Yamaha RD 200 at 16
Yamaha RD 350 at 17
Honda CB 750 F at 18
Honda V45 Sabre at 24
BMW K100RS at 27
BMW R100GS at 34
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post #3 of 6 (permalink) Old Jun 20th, 2012, 1:44 pm Thread Starter
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I hadn't thought to do a TPS reset, but I have tried it now and unfortunately it hasn't improved it.

What else do you think it might be?
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post #4 of 6 (permalink) Old Jun 20th, 2012, 2:46 pm
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Vacuum leaks.. Intake manifolds O-rings or the rubber connectors between the stubs and throttle bodies.

Also, you don't have a charcoal canister so there should be a hose bridging the 4 vacuum ports together, if split or disconnected that could cause a pretty good vacuum leak.

Altough you can run an unlit propane torch around the intake parts to check for leaks, if the propane gets aspirated idle will change and point to the leak, I much prefer using a proper vacuum gauge. Connected at each of the previously mentioned vacuum ports in turn and watch for major needle fluctuations or discrepancies between each cylinder. Easier if you have access to a 4 column type (or dial) gauge, then you can connect them all but a single should work.

Good Luck!

Benelli 50cc at 14
Yamaha RD 200 at 16
Yamaha RD 350 at 17
Honda CB 750 F at 18
Honda V45 Sabre at 24
BMW K100RS at 27
BMW R100GS at 34
BMW K1200RS at 53
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post #5 of 6 (permalink) Old Jun 21st, 2012, 4:06 am
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Good tips from 'H'

Older bike and perished engine breather hoses (pig to get to) are common.

Older bike and the O2 sensor may have got sluggish. It can be a pig to get out of the muffler, but the Universal Bosch alternative works and is not big money.

The rpm 'hunting' you get is due to the Efi closed loop falling outside its range to maintain constant rpm. That can be air leaks which the electronic mixture control cannot cope with, the O2 sensor not detecting the air/fuel ratio, or faults in the 'closed loop' engine breathing which the electronic control has built in compensation for. Less likely is a problem with the throttle potentiometer which can go intermittent at the bottom end. Don't mess with the TPS settings as doing anything should be only checks on track resistances



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Last edited by voxmagna; Jun 21st, 2012 at 4:16 am.
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post #6 of 6 (permalink) Old Jun 21st, 2012, 8:40 am
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Yes the TPS settings....but for the manual reset, no messing with that without a GS911 or dealer software. I haven't tested my theory yet, next winter....but it does look like the manual reset may not always do it if the TPS is way out of whack. I know others had problems with that also on R-bikes and either had to do the reset numerous times before it took or.....do it with a GS911 or such.

O2 sensor, altough the GS911 will give you a function graph showing normal operation, no real way to test it on your own. However at $70.00 or so for the universal Bosch I just replaced mine for peace of mind. On that note and if you go looking at the intakes, please do not use any sillycone lubes anywhere near the manifolds or O-rings,or any intake/fueling parts, it will get on the O2 sensor and pollute it.

I only had one instance of erratical idling on my bike.....high altitude gasoline bought way up there in Colorado somewhere in a small out of the way general store. May not be related but going back down the hills and a fresh tank of gas and it cleared out.

Corrosion creeping toward the intake manifold O-rings and slightly bowed manifolds.....but that I fixed preventively the following winter.

And edit....when I did the preventive maintenance on my intake system I did find a loose throttle plate, was starting to bind in the throttle bodies from the wear marks. Someone else found the exact same not long ago,and even same No.3 cylinder. Scary to me thinking about that screw falling off and getting aspirated in the engine with obvious nasty consequences.

Benelli 50cc at 14
Yamaha RD 200 at 16
Yamaha RD 350 at 17
Honda CB 750 F at 18
Honda V45 Sabre at 24
BMW K100RS at 27
BMW R100GS at 34
BMW K1200RS at 53

Last edited by H96669; Jun 21st, 2012 at 9:27 am.
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