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Author Topic: bucks, runs on maybe 2 cylinders and then back to normal  (Read 1815 times)

Offline zipster68

  • ^ Motobrick Curious
  • Posts: 104
bucks, runs on maybe 2 cylinders and then back to normal
« on: July 17, 2019, 04:30:06 PM »
Hi Brickers,
I've got a new (intermittent) problem on my 86 K100.  Bike starts easy, idles great and after maybe 10-15 minutes bucks a couple times and acts like it's running on 2 cylinders, for maybe 15 seconds (doesn't stall out).  Then runs perfectly normal.  This has happened maybe 3 times.  Doesn't appear related to wetness, temperature.  I've got fresh gas in there and the tank looks clean.  I've got a very new looking coil pack that I've swapped in a couple years ago.
Possible issues...
fuel filter
injectors
throttle pos'n sensor
Looking for suggestions if you've got any.
Cheers,
Ray
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  • Ferndale, Michigan
  • 1986 K100RS, 1977 naked Goldwing, 1975 Yamaha RD350 smoker, 1978 Vespa P200, 1980 Lambretta Jet 200

Offline natalena

  • ^ SuperNatural Motobricker
  • Posts: 611
Re: bucks, runs on maybe 2 cylinders and then back to normal
« Reply #1 on: July 17, 2019, 04:44:52 PM »
You left out the 4-pin ;)
If it runs great after the sporadic episodes, I'd be guessing electrical.
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  • MST
  • 1987 K75s #0919, '05 Sportster 1200C, '21 ARGO 8x8, '24 KLR650
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Offline Laitch

  • Faster than a speeding pullet
  • Administrator
  • ^ Quintessential Motobricker
  • Posts: 10152
Re: bucks, runs on maybe 2 cylinders and then back to normal
« Reply #2 on: July 17, 2019, 05:05:07 PM »
Check and clean the four-pin pump connector.
Check all the interior fuel lines for clamp tightness.
Clean and tighten the battery negative ground on the transmission.
Check the battery connections for tightness.
Check the ground connections on the backbone frame member under the tank.
Change the fuel filter if you don't know how old it is, or if it's a Fram filter.

There's more after this. :giggles

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  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles
I wept because I had no radials until I met a man who had no splines.
https://tinyurl.com/RillRider

Offline daveson

  • ^ Quintessential Motobricker
  • Posts: 1043
Re: bucks, runs on maybe 2 cylinders and then back to normal
« Reply #3 on: July 17, 2019, 08:50:40 PM »
Temporary wonky on two cylinders, maybe check coil connections.
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  • Victoria, Australia
  • Current;'85 K100RT~100,000km; four other bricks. Past; 1500 Vulcan, V Star 650, KLX 250(dirt bike) TT250(dirt bike)

Offline zipster68

  • ^ Motobrick Curious
  • Posts: 104
Re: bucks, runs on maybe 2 cylinders and then back to normal
« Reply #4 on: July 17, 2019, 09:35:46 PM »
Don at Detroit BMW says water in the gas and/or tank.  My cap is installed backwards and that isn't good either for water.  I'm gonna pump all of that gas out, mop the bottom and start fresh. 
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  • Ferndale, Michigan
  • 1986 K100RS, 1977 naked Goldwing, 1975 Yamaha RD350 smoker, 1978 Vespa P200, 1980 Lambretta Jet 200

Offline Scott_

  • Administrator
  • ^ Quintessential Motobricker
  • Posts: 2193
Re: bucks, runs on maybe 2 cylinders and then back to normal
« Reply #5 on: July 17, 2019, 09:48:02 PM »
Don't forget to check/clean the multi-pin plug on the ignition control module..
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  • My Garage
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Offline zipster68

  • ^ Motobrick Curious
  • Posts: 104
Re: bucks, runs on maybe 2 cylinders and then back to normal
« Reply #6 on: July 18, 2019, 09:23:32 AM »
I'll check it.  Where the hell is it?
-Ray
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  • Ferndale, Michigan
  • 1986 K100RS, 1977 naked Goldwing, 1975 Yamaha RD350 smoker, 1978 Vespa P200, 1980 Lambretta Jet 200

Offline Laitch

  • Faster than a speeding pullet
  • Administrator
  • ^ Quintessential Motobricker
  • Posts: 10152
Re: bucks, runs on maybe 2 cylinders and then back to normal
« Reply #7 on: July 18, 2019, 12:48:54 PM »
Ignition control unit is at the left arrow; its plug is at the right arrow.
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  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles
I wept because I had no radials until I met a man who had no splines.
https://tinyurl.com/RillRider
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