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1Back to top Go down    Rough Running 1997 K1100LT on Tue Mar 17, 2015 5:25 pm

mike d


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This is to help another BMW Club UK member.

1997 K1100LT, bought on a whim!

The bike starts easily and at idle sounds perfect.

Go for a spin and it starts to run rough (on 3 cylinders). each time it seems to be number 4 plug fouled up/flooded.

Jobs performs so far:

Compression check - Good
It has a new fuel pump and fuel filter.
The injectors were checked and showed to have a similar spray pattern.
Throttle bodies balanced.
Fuel pressure checked and seems o.k.
New plugs fitted.
Replacement plug leads & coils (from my known good K1100)
Replaced TPS (From my known good K1100)
ECU swapped out (as above)
Electrical connections to ECU, coil etc. checked and cleaned (but not found to be bad anyway.
The Hall sensor has been changed and ignition retimed (on the original the timing was out). Since then the old hall sensor has been refitted with no improvement.
I have measured the resistance of the coolant sensor from the ECU cable connector. This is different pins to the K100, but all seemed o.k.

I have requested he check the valve clearances, and swap over the injector from number 4.

Any more ideas?

Mike

    

2Back to top Go down    Re: Rough Running 1997 K1100LT on Tue Mar 17, 2015 6:31 pm

Ringfad

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I had a similar problem on my K100 16V - turned out to be a bad connection on no 4 injector - when I swapped the injector cable with no 3 the problem followed and was then easily fixed by repairing the bad connection on the no 4 injector cable.

I had to strip back the hard rubber covering of the injector plug connector to findthe problem.


Since you have a spare it might be worth temporarily replacing the whole fuel injection loom



Last edited by Ringfad on Tue Mar 17, 2015 6:34 pm; edited 1 time in total (Reason for editing : update)


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;BMW;K100RS Style Black 1987 105K Km ;BMW; K1 Black 1993 51KKm ;BMW;K1100RSRed 1993 70k miles ;BMW; K100 16V Black (ex ElectricMonk)
    

3Back to top Go down    Re: Rough Running 1997 K1100LT on Tue Mar 17, 2015 7:39 pm

mike d


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Thanks,

Worth a go. Will ask him to swap the connectors over (or at least give them a good looking at!

Mike

    

4Back to top Go down    Re: Rough Running 1997 K1100LT on Sat Apr 04, 2015 1:27 pm

mike d


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O.k. so time for an update.

The #2 inlet valve - cyl 1 (working from the front of the bike) is tight at 0.08mm.

The #5 exhaust valve - cylinder 3 is loose at 0.38mm

All other clearances are within spec.

Now if the problem had been valves on cylinder 4 I would be more happy, but at least this is the first hard fault we have found!.

He hasn't as yet swapped over the injector electrical connections or the injectors themselves (I did ask him to do this before checking the valves).

So, knowing a valve is tight, but only one of the two on a different cylinder to that which was suspect, could this be the actual fault.?

Mike

    

5Back to top Go down    Re: Rough Running 1997 K1100LT on Sat Apr 04, 2015 9:58 pm

RicK G

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I don't think that it is the problem, if it was a loose inlet and tight exhaust it would be more likely but still I would not expect that to be a problem.
I chased a similar problem with my K1100 and it turned out to be a slightly retarded TPS. It was only a matter of about 0.5mm at the screws but what a difference. It was OK cold but as soon as it got to operating temp the #2&3 cyl would start missing. Since I got it right it has been running well. Because it was 2&3 cylinders I was chasing and intermittent electrical problem.


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If everything seems under control then you aint goin fast enough:- Mario Andretti
Bikes 1986 K100RT, 1993 K1100 LT, 1994 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 & 1976 SR 500 Yamaha for now
    

6Back to top Go down    Re: Rough Running 1997 K1100LT on Sun Apr 05, 2015 12:57 pm

mike d


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Hi Rick,

Thanks for the feedback. The TPS has been swapped for a known good unit (mine) and set using a GS-911 (plus Charlie has also used a multimeter to set it), so I don't think that is the issue. Plus of course it only seems to be missing on number 4 cy;inder.

I may try to get back to visit him this wee, but he is an hour away and I will be doing some part time work this week.

Will post another update when some more testing has been completed.

Mike

    

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