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1Back to top Go down    Coils. To replace, or not to replace? on Mon Jun 25, 2018 9:32 am

George_Pap

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Hi commuynity. Its been a while for me being silent without screaming for help. Smile
So its time again. I have a persistent and randomly appearing problem with engine cutouts. Sometimes when warm, sometimes when starting. It idles but when trying to rev more than 2000rpm it stalls.
it's no grounding, its no pump, no hall effect sensor, no ignition switch, no pump connector ( all of these checked/tested ).
I'm suspicious with the coils and the temp sensor.
After doing my studies in this forum and FB pages i did measure the secondary and primary coil terminals and also the HT Leads.
The 3rd cylinder cable lead had triple the resistance of the other cables. Connector was corroded.


Also the coils gave the following measurements on the secondary terminals:

Coil number one (close to engine) 11.73 kΩ
Coil number two (rear, close to battery) 14.30 kΩ

The measurement were taken with the bike hot after 20km ride. My coils are the older type ones, full black. Dont know if previous owner got them changed, bike has 102.000km now.

So, could coils cause the issue shown on the video below? Thank you!





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K100RT (Early 1985 -nonABS)
    

2Back to top Go down    Re: Coils. To replace, or not to replace? on Mon Jun 25, 2018 1:01 pm

Laitch

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@George_Pap wrote:The 3rd cylinder cable lead had triple the resistance of the other cables. Connector was corroded.
Certainly the spark plug cable terminals should not be corroded and the coil connection for it should not be corroded either. Did you clean its end terminals and the coil's terminal then test engine performance again? A replacement for that cable might be needed.


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1995 K75T 68,000 miles
    

3Back to top Go down    Re: Coils. To replace, or not to replace? on Mon Jun 25, 2018 1:09 pm

George_Pap

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I sprayed it with WD40 Contact cleaner and measured it again but from 17 Ω dropped to 15+
Guess the coil also shows higher resistant because is the one that the faulty cable plugs into.
Thank you Laitch


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4Back to top Go down    Re: Coils. To replace, or not to replace? on Mon Jun 25, 2018 10:11 pm

Dai

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I think what Laitch means is; did you clean all the green crap off the lead and from the inside of the coil post? When I first got LFB my leads were so bad that the connectors inside the spark plug caps were simply a pile of green dust; yet the bike kept running!


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'83 K100 upgraded to K100RS spec
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
'03 Suzuki Blandit GSF600SK3 (NFS any more because wifey has claimed it)
    

5Back to top Go down    Re: Coils. To replace, or not to replace? on Tue Jun 26, 2018 4:38 am

charlie99

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that doesn't sound likeignition lead - coils issue at all

more like fuel starvation ..air leaks etc

just my thoughts


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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
    

6Back to top Go down    Re: Coils. To replace, or not to replace? on Tue Jun 26, 2018 4:46 am

George_Pap

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@Dai wrote:I think what Laitch means is; did you clean all the green crap off the lead and from the inside of the coil post?

No i didnt do a special cleaning . Just a spraying. But intent to. Other thought as i wrote in the post subject is to replace the coils with the newer type ones. I read everywhere that the old type of coils could't stand up to this mileage of my bike. Actually is a miracle that they even operate.
Tough decisions scratch


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7Back to top Go down    Re: Coils. To replace, or not to replace? on Tue Jun 26, 2018 4:50 am

George_Pap

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@charlie99 wrote:that doesn't sound likeignition lead - coils issue at all

more like fuel starvation ..air leaks etc


Charlie a week ago replaced all intake rubbers, including manifolds, upper tubes, crankcase breather hose , fuel lines and tested for leaks with success. Previously had serious air leaks.
Though i second your feeling of "fuel starvation"
Just wondering if this could be caused by the coils.
Other suspicion is the Temp sensor due to the fact that this occurs whenever high atmosphere temps show up.
Really confused.


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K100RT (Early 1985 -nonABS)
    

8Back to top Go down    Re: Coils. To replace, or not to replace? on Tue Jun 26, 2018 5:22 am

duck

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When's the last time the fuel filter was changed?


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Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
http://www.ClassicKBikes.com
    

9Back to top Go down    Re: Coils. To replace, or not to replace? on Tue Jun 26, 2018 6:02 am

George_Pap

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@duck wrote:When's the last time the fuel filter was changed?
Α couple of months ago.

..but.

The bike was sitting for almost nine years. After the mechanic installed a new but not BMW specked fuel pump without even cleaning the tank interior me myself changed the fuel filter.
After solving various problems with the engine ( all had to do with cutouts or non starting ) i also replaced the pump with a genuine BMW Bosch one, a couple of weeks after the filter change.
But did not change the filter again. At that point i cleaned the fuel tank too, because after removing the wrong pump i fount mug / debris under the pump seat.
So i m afraid that maybe the filter got some particle in it.
i have already ordered a new one to do that change though.


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K100RT (Early 1985 -nonABS)
    

10Back to top Go down    Re: Coils. To replace, or not to replace? on Fri Aug 10, 2018 10:17 am

George_Pap

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I would like to report that the problem solved as i replaced (same time) coils with the new type ones, fuel injectors ( four hole type from tills.de ) and a set of NGK HT leads. K is running as a charm now, just a tad of higher fuel consumption.
Thank you all for your precious advices.


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11Back to top Go down    Re: Coils. To replace, or not to replace? on Fri Aug 10, 2018 2:02 pm

charlie99

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well done ...I think the injector retro fit was a good move ... so glad you got it running far better

did you happen to measure the old coils ? what was the result ?

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
    

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