BMW K bikes (Bricks)

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1Back to top Go down   K100RT engine missing at low power Empty K100RT engine missing at low power on Fri Nov 06, 2015 4:09 am

renriv

renriv
active member
active member
My K100 is idling well and is fine under load but running quietly in town at 2000rpm the engine misfires irregularly. A slight opening of the throttle and it's fine, and an increase in revs to 2500 also seems to fix it. Any suggestions anyone ?

    

2Back to top Go down   K100RT engine missing at low power Empty Re: K100RT engine missing at low power on Fri Nov 06, 2015 7:05 am

floyd

floyd
Life time member
Life time member
likely totally unrelated but i feel like 'expressing myself' as it were hahaha


The last few days ive had this weird kinda 'missing' or 'surging' - noticeable in all gears mostly around 3k - 4k revs. 

Very minor, the tacho remains constant etc. Its so subtle I actually question if its really there - but I know it is.

I think i discovered the problem today....

The under seat EFI computer's plug wasnt seated home correctly - i.e. the metal clip that holds it in place wasnt doing its job. I only discovered this this arvo while poking around in the area.

Anyways...point is ive had a few niggling issues (such as the bike just stopping in the middle of no where) caused by this connector coming loose.

good luck mate


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K100 with lots of K1100 bits - mongrel of a thing...
    

3Back to top Go down   K100RT engine missing at low power Empty Re: K100RT engine missing at low power on Fri Nov 06, 2015 7:18 am

92KK 84WW Olaf

92KK 84WW Olaf
Life time member
Life time member
That connector under the seat has been the source of quite a few no go bikes like Floyds post so I reckon before going at anything else suss that one out and make sure its al good. Loose connection here can mean no signal from Hall Sensors, Temp sensor and more.

Another potential issue is the plug front left of the bolted down gas tank [early tank, not the clipped one] that has the power supply for the fuel pump. This also can go loose creating occasional cut outs.l


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1992 K100LT 0193214 Bertha Alaska Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 58,645 now 98,780 miles
1983 K100RS 0011171 Fricka 29,495 miles Damn K Pox Its a Bat outta Hell No 32,600 miles
    

4Back to top Go down   K100RT engine missing at low power Empty Re: K100RT engine missing at low power on Fri Nov 06, 2015 7:22 am

floyd

floyd
Life time member
Life time member
@92KK 84WW Olaf wrote:Another potential issue is the plug front left of the bolted down gas tank [early tank, not the clipped one] that has the power supply for the fuel pump. This also can go loose creating occasional cut outs.l

Yep, Olaf hit that one on the head too. I had issues with that fuel tank plug (the small round 4 pin jobby on the early bikes - pre 85)

Replaced it with the 'spare' from the relay box and also tightened the pins up, and its been fine since.

But the under seat EFI computer plug really needs an eye kept on it....even more so if the rubber shock mounts have degraded and it bounces around a bit...


__________________________________________________
K100 with lots of K1100 bits - mongrel of a thing...
    

5Back to top Go down   K100RT engine missing at low power Empty Re: K100RT engine missing at low power on Fri Nov 06, 2015 7:28 am

Holister

Holister
Life time member
Life time member
Could be a number of things but it sounds like it could be electrical to me. Is the misfire getting more frequent?

I'd start with the spark plugs. 
You can test them with a dmm. Your plugs should be non-resistor type (NKG D7EA) and so should measure very low resistance... around half an ohm. If resistance is higher they're on the way out. If resistance is infinite, the plug has gone 'open' and is dud. They can still randomly fire in that state.

You can test the insulation by measuring from either end of the plug to the threaded body. If you get any reading the plug is dud.

Make sure you have the terminal nut screwed firmly on the end. The lead plugs don't like it when they're missing.

You can test the leads as well. They should measure around 5kilohm


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1989 K100RT     VIN No.  0097367 (naked)  
1996 K1100RS   VIN No.  0451808
 K100RT engine missing at low power Austra12    Fuel:  95 Octane
Engine Oil: Nulon Full Synthetic 15W50
Gear Box Oil:  Nulon Synthetic 75W90
    

6Back to top Go down   K100RT engine missing at low power Empty Re: K100RT engine missing at low power on Fri Nov 06, 2015 7:34 am

RicK G

RicK G
VIP
VIP
Also check that all the throttle body clamps are tight and that the manifold rubbers aren't split just under the clamps.
Wornout spark plugs are also a common cause of eratic missfire.  Check leads and coil connections, check the inside of the plug caps for white powdery stuff and make sure the little bobbins are on the top of the plugs. Corrosion in the plug lead connectors on the coils is also a common problem.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 1993 K1100 LT, 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 for now
    

7Back to top Go down   K100RT engine missing at low power Empty Re: K100RT engine missing at low power on Sat Nov 07, 2015 12:31 pm

Brad-Man

Brad-Man
Life time member
Life time member
Could also have a very small vacuum leak.

Only affects off throttle because so small, but lean mixtures are harder to ignite.


__________________________________________________
Toys don't make the man - Man makes the toys....
K100RT engine missing at low power Usa-lo10
    

8Back to top Go down   K100RT engine missing at low power Empty Re: K100RT engine missing at low power on Sat Nov 07, 2015 12:32 pm

Brad-Man

Brad-Man
Life time member
Life time member
Could also have a very small vacuum leak.

Only affects off throttle because so small, but lean mixtures are harder to ignite.

Not saying this is likely, but entered for completeness.


__________________________________________________
Toys don't make the man - Man makes the toys....
K100RT engine missing at low power Usa-lo10
    

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