BMW K bikes (Bricks)

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1Back to top Go down    Poor/no spark on cylinders 2 & 3 on Sat Jan 13, 2018 11:56 pm

renriv

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My K100 is throwing fits and 'loses' cylinders 2 & 3. Spark on others very weak when checked. Will suddenly come back and all is well for a while till it happens again. Swapped coils around to see if it was a coil, but still 2 & 3. Fuel pressure checks out and pump working. At present almost no spark on 1 and 4, none on 2 & 3, so not running at all. Interesting dilemma that has me stumped - not very hard to do that though. Any suggestions appreciated. Thanks, Allan scratch

    

2Back to top Go down    Re: Poor/no spark on cylinders 2 & 3 on Sun Jan 14, 2018 12:15 am

RicK G

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Does it run OK when cold and play up when hot which indicates the hall sensors are cactus. Also check the plug at the ICU just behind the steering head below the top tube is plugged in firmly.


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"Every normal man must be tempted, at times, to spit upon his hands, hoist the black flag, and begin slitting throats." from Mencken's 1919 Prejudices

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

3Back to top Go down    poor/no spark on cylinders 2 & 3 on Sun Jan 14, 2018 12:25 am

renriv

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Temp seems to make no difference. Will check plug. Thanks

    

4Back to top Go down    Re: Poor/no spark on cylinders 2 & 3 on Sun Jan 14, 2018 1:02 am

charlie99

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don't check them ,,,, clean them regardless
once your in there, best to get it done and dusted

good luck


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cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

5Back to top Go down    poor/no spark on cylinders 2 & 3 on Sun Jan 14, 2018 1:15 am

renriv

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Interestingly if i let the spark plug metal shrouds touch when testing for spark i get a magnificent spark. Does that point to plug leads ?

    

6Back to top Go down    Re: Poor/no spark on cylinders 2 & 3 on Sun Jan 14, 2018 4:07 am

charlie99

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yes it does

the plug leads are resistive ...but the wire may have broken just at the crimp type socket termination (where the conductor is clamped to the electrode )

often the socket part that makes contact with the spark plug top corrodes up , this could be because they haven't been pushed home correctly , or the ferrule that fits on top of the thread of the plug hasn't been fitted when changing (especially the ngk types )

I would suggest get at least two elcheapo pre made ignition leads from your auto store (usually blue in colour , but ihave seen grey as well ) the resistive silicon type

and fit them to cylinders 1 and 4 .....or 2 and 3
then tie some copper wire around the body (threaded section of the spark plug ) and make a connection to a screw nearby fit the leads to the plugs and coils then turn the motor over (withoutany plugs fitted ) so it spins fast and without compression

observe the spark across the plugs to see if it has made a big difference

hope that helps and you follow what I mean

cheers






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cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

7Back to top Go down    Re: Poor/no spark on cylinders 2 & 3 on Sun Jan 14, 2018 7:33 am

Dai

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Corrosion inside the plug cap will do that too. If it's a mass of green in there, introduce it to the nearest bin.


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'83 K100 upgraded to K100RS spec
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'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
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8Back to top Go down    Misfire on Sun Jan 14, 2018 9:16 am

norton71

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Used to have a 1971 Valiant Charger that would run fine and then just stumble for about 2-5 seconds at 90 MPH (no power at all) before running fine again ..went on for several weeks before i pulled the coil lead from the dizzy cap..inside of the coil lead holder (brass) was covered in green crap i assume was from water getting in and reacting with the brass over time ...far as i could work out the green stuff resulted in a high resistance that would result in no spark through the dizzy until the voltage rose enough to find another way to ground itself to the nearest earth. Have seen much the same with spark plug wire connections. (and in those days Deoxit wasn't around)

    

9Back to top Go down    poor/no spark on cylinders 2 & 3 on Sun Jan 14, 2018 11:56 pm

renriv

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Checked plugs and they had no ferrule on top. Found some and put them on which seemed to help but still inconsistent. Come to a halt now as went to go for a ride and fuel pouring down over motor. thought it was tank but no, the fuel line out of the tank had split. Replace that and still got fuel everywhere, so time to have a break. Can't see where it's coming from as it seems to be behind the air box above the injectors. Maybe another hose, but have to do a bit of checking.Evil or Very Mad

    

10Back to top Go down    poor/no spark on cylinders 2 & 3 on Mon Jan 15, 2018 12:44 am

renriv

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Seems the fuel leak is coming from the fuel pressure regulator. Have to put a post under fuel problems to see how to get to that. Manual doesn't help much. Thanks for your help with the spark. The i get the fuel leak fixed I'll let you know how it went !!

    

11Back to top Go down    Re: Poor/no spark on cylinders 2 & 3 on Mon Jan 15, 2018 3:39 am

charlie99

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eeek ...could have a lot to do with it not running also
hope you have a powder type fire extinguisher real handy

good luck


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cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

12Back to top Go down    poor/no spark on cylinders 2 & 3 on Wed Jan 17, 2018 11:10 pm

renriv

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Found fuel leak ! Must not have had fuel return line clamped properly on fuel tank !! All good now and have taken chance to degrease engine behind air box too. All fuel lines now good and bike running smoothly, although the spark still seems very weak when i take plugs out and check. However since it's running well i'm leaving well alone. Thanks for your help.
Regards
Allan

    

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