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1Back to top Go down   Erratic revs 1984 BMW K100 RS Empty Erratic revs 1984 BMW K100 RS Sat Jun 05, 2021 12:55 pm

WayneD

WayneD
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I've owned and ridden my bike since last March 2020 and have only put about 1,500 miles on the clock, previous owner had told me that he'd done a full service and ridden her back from Heinsberg in Germany at the end of January 2020.
So my bike was in storage for 6 weeks over the winter,dry and cool lockup.
 She started up first time when I took her out , rode her home , rod her her around for a week, refuelled her and rode 8 miles parked up at a friends for a cuppa, came out 3 hours later... started straight away... 300 yards down the road the revs dropped , I dropped a gear, revs still dropping, dropped into 3rd ... then 2nd throttle wide up ... bike is kangarooing down the street with erratic revs...managed to get home 3 miles.
went online checked here and other places for symptoms....  
decided to check air/ fuel/ electrics ....problems I found  
* spark plug 1 showed soot
* Spark plug 2 plug cap was damaged not connected to spark plug
* Spark plug 3 wet unburned fuel
* Air filter was grey with muck


I replaced all the Spark plugs ,  3 of the Spark plug caps and the air filter 

fired her up and ran nicely ....... went out yesterday battery flat... battery on charge overnight , wouldn't turn over today... hooked her up to spare battery... started and the problem is back  ... any suggestions ?
 
 i've put a link to a video of  what she sounds like  .... during the video the rev surges and drops are not me over revving the throttle

https://drive.google.com/file/d/1ygBt9YAj2iyiwDLspKxgwqCfHw6TBPyv/view?usp=sharing

    

2Back to top Go down   Erratic revs 1984 BMW K100 RS Empty Re: Erratic revs 1984 BMW K100 RS Sat Jun 05, 2021 2:04 pm

Laitch

Laitch
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@WayneD wrote:. . .  previous owner had told me that he'd done a full service and ridden her back from Heinsberg in Germany at the end of January 2020.
* Air filter was grey with muck
The condition of the air filter contradicts the owner's assertions. Check the fuel filter to see if it's clogged. Check the tank's interior fuel lines to determine if they're loose or deteriorating. Verify that the Jetronic plug is tightly seated. Verify that the battery's ground connection is clean and tight on the transmission. Check the condition of the z-hose connection from the crankcase to the air box. Maybe you'll get lucky by addressing only these conditions.


__________________________________________________
1995 K75 81,000 miles
Erratic revs 1984 BMW K100 RS Usa-lo10
    

3Back to top Go down   Erratic revs 1984 BMW K100 RS Empty Re: Erratic revs 1984 BMW K100 RS Sun Jun 06, 2021 8:09 pm

WayneD

WayneD
New member
New member
@Laitch wrote:
@WayneD wrote:. . .  previous owner had told me that he'd done a full service and ridden her back from Heinsberg in Germany at the end of January 2020.
* Air filter was grey with muck
The condition of the air filter contradicts the owner's assertions. Check the fuel filter to see if it's clogged. Check the tank's interior fuel lines to determine if they're loose or deteriorating. Verify that the Jetronic plug is tightly seated. Verify that the battery's ground connection is clean and tight on the transmission. Check the condition of the z-hose connection from the crankcase to the air box. Maybe you'll get lucky by addressing only these conditions.
thanks for the suggestions, I've been and checked  what you mentioned and also replaced the fuel filter in the tank .. but I'm still getting the same problem.



Last edited by WayneD on Mon Jun 07, 2021 6:11 pm; edited 1 time in total

    

4Back to top Go down   Erratic revs 1984 BMW K100 RS Empty No go Sun Jun 06, 2021 8:25 pm

daveyson

daveyson
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You might have condensation in the tank from its storage time, especially if the tank was low. It might work if you lean it to the right so the water goes away from the pump.


__________________________________________________
11/1985 bmw k100rt (late model)  Vin. 0090567
 ~120,000 km
    

5Back to top Go down   Erratic revs 1984 BMW K100 RS Empty Re: Erratic revs 1984 BMW K100 RS Sun Jun 06, 2021 8:57 pm

Laitch

Laitch
Life time member
Life time member
@WayneD wrote:thanks for the suggestions, I've checked  what you mentioned and also replaced the fuel filter in the tank .. but I'm still getting the same problem.
It looks like you're crossing into bad luck territory. Tell us what else you have investigated to remedy this condition.


__________________________________________________
1995 K75 81,000 miles
Erratic revs 1984 BMW K100 RS Usa-lo10
    

6Back to top Go down   Erratic revs 1984 BMW K100 RS Empty solved Tue Sep 21, 2021 1:18 pm

WayneD

WayneD
New member
New member
@Laitch wrote:
@WayneD wrote:thanks for the suggestions, I've checked  what you mentioned and also replaced the fuel filter in the tank .. but I'm still getting the same problem.
It looks like you're crossing into bad luck territory. Tell us what else you have investigated to remedy this condition.
so after much fiddling i took out the fuel pump while bench testing it I realised it was making a 'squeeling' sound... ordered and fitted a new fuel pump... problem solved.
 out of curiosity I opened the old pump and found the inside 'gunked' up with a brown grey sludge that smelt of petrol and burning rubber and appeared to be stopping the fuel from passing through.. showed it to a local mechanic who said he thinks its a dissolved a seal possibly caused by ethanol in the petrol

    

7Back to top Go down   Erratic revs 1984 BMW K100 RS Empty Re: Erratic revs 1984 BMW K100 RS Tue Sep 21, 2021 4:04 pm

92KK 84WW Olaf

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The ethanol does that to the damper mounting, right diagnosis!. Did you replace it?


__________________________________________________
1992 K100LT 0193214 Bertha Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red 578 bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 689 58,645 now 106,950 miles Deceased.
1983 K100RS 0011171 Fricka 606 Alaska Blue 29,495 miles Damn K Pox Its a Bat outta Hell Now 37,190 miles. 
1996 K1100LT 0233004 Lohengrin Mystic Red 38,000 miles currently 42,640 miles.

Past:
1968 Yamaha 80 YG1
1971 Yamaha 125 YAS-1
1968 Honda 125 SS
1970 Honda CD 175
1973 Honda CB500-4
Honda CX 500
    

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