Author Topic: Stumped  (Read 3361 times)

Offline notalec

  • Curious
  • Posts: 8
Stumped
« on: May 13, 2019, 11:18:42 PM »
I have a 92 k75. I left for a few months so it sat in the garage neglected for a while. Before that, I had had some other issues. I replaced the engine last year due to failed main bearing. Lubed the splines while I was at it. Drove it around for a while and killed the battery with short in town trips, and in turn the starter relay and the starter. After that, it would sometimes start to sputter like there was a misfire in one of the cylinders. I was able to ride it around some before I had to leave for a while. I came back the other week and finally got around to firing it up. With the choke on it fired up right away. I rode it across the street to the other garage so I could wash the storage dust off of it. A few hours later I wanted to go for a short ride to see if I could take another stab at what was causing the occasional misfire. I started up, got warm, got off choke, and then I stalled it like a clutz. And that was all she wrote. The motor won't fire at all anymore.

I checked the fuel injectors by removing them and checking the spray against a piece of cardboard. I pulled each plug out and tested with each wire and the all provided spark. I checked the air filter and its still new from the engine swap. I checked the compression and saw 120psi on all three +/- 2. I let the battery charge overnight. I removed power to the ECU so it could reset. Lights all work, gauges all work.

On the advice of a youtube video, I put about 10cc of oil in each cylinder and tried to start it. I was able to get it to fire long enough to burn off the oil and that was it.

Time to call a priest?
  • Eugene Oregon
  • '92 k75 '81 cb900c '75 gl1000 '72 cb750 '73 cb750

Offline billday

  • ^ Quintessential Motobricker
  • Posts: 1341
Re: Stumped
« Reply #1 on: May 14, 2019, 06:09:30 AM »
"Short in town trips" don't kill batteries.  Something else was wrong, wonder what?
  • New York State, USA 10977
  • 1985 K100

Offline Laitch

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Re: Stumped
« Reply #2 on: May 14, 2019, 08:47:42 AM »
"Short in town trips" don't kill batteries.  Something else was wrong, wonder what?
+1

Your timeline of events is unclear to me but it appears that you rode the moto intermittently for short distances. That wasn't enough to keep the battery charged during months of idleness. When idle, the battery was slowly discharging. The battery depends on a good charging system and regular riding to keep it in good condition unless it is attached to an appropriate charger when it is idle, or its ground strap to the transmission has been disconnected after it is has been fully charged. Your amount of riding followed by neglect did not maintain a full charge. The battery probably has discharged excessively and has lost ability to hold sufficient starting voltage for very long. The voltage regulator might also be defective.

A battery in a moto that "sat in the garage neglected" for a few months might be ruined. A multimeter can be used to determine its present resting voltage. Have it load tested at a local auto parts store that offers that service. The simplest way to preserve battery life is to disconnect the battery ground strap from a fully-charged battery when the moto is going to be neglected for more than a week. Alternatively, attach it to an appropriate battery maintenance charger.

Your battery seems kaput.
  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

Offline The Mighty Gryphon

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Re: Stumped
« Reply #3 on: May 14, 2019, 09:24:27 AM »
I'm going with the dead battery as well.  How old is it?  Get it load tested, Autozone does free load testing if I recall.  Normally, if the engine starts right away the alternator will put back the power the starter used in under a minute of run time.

Storing a battery that doessn't have a full charge on it will cause it to chemically die in about a month.  You always need to have a full charge when you store.  Then you don't even need the maintainer, unless there is a small load connected to it.

  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline Chaos

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  • Mars needs women!
Re: Stumped
« Reply #4 on: May 14, 2019, 10:55:20 AM »
does it crank but not fire?  wouldn't fire after you washed it?  could be something got wet.  How old is the gas, always good to eliminate that variable with a fresh tank
  • sw ohio
1987 K75S    VIN 0231
Original owner, Original litter
200,000 miles (plus or minus) and 5 paint jobs
sold 6/23
2023 Ural 2WD sidecar (BMW's bastard step child)

Offline notalec

  • Curious
  • Posts: 8
Re: Stumped
« Reply #5 on: May 14, 2019, 11:50:42 AM »
I didn’t think of the fuel!! That could be it. I have a bunch of bikes. So this one wasn’t ridden a ton. I have no idea how old that fuel is. Maybe 6 months of more.

The battery is new. It cranks really well. I’m used to older Japanese bikes. Lots of short trips will kill batteries in those bike. But I guess that’s not the case on the k bikes.
  • Eugene Oregon
  • '92 k75 '81 cb900c '75 gl1000 '72 cb750 '73 cb750

Offline The Mighty Gryphon

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Re: Stumped
« Reply #6 on: May 14, 2019, 07:00:52 PM »
K bikes have automobile alternators.  Most Japanese bikes don't. 
  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline Chri5

  • ^ Motobrick Curious
  • Posts: 61
  • Buy it - Break it - Rebuild it!
Re: Stumped
« Reply #7 on: May 16, 2019, 10:36:20 PM »
Resistance check on the coils i had similar issue of cracking but not firing or difficulties staying alive and occational misfire and one of my coils had an intermittent connection
  • United Kingdom
  • K100RS
Yamaha FZ6n-s2 electric conversion(Electric motor 240nm of instant torque)
Kawasaki Z750R
85 BMW K100RS
Buy - Break - Rebuild - Repeat!

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