Author Topic: power loss whack - '90 K75  (Read 793 times)

Offline herseyb

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power loss whack - '90 K75
« on: June 17, 2019, 05:58:02 PM »
 :falldown:

Well, I was all loaded up and trying to hit the high speed ferry in MKE for a long weekend of moto-camping and FINALLY testing the dawn 2 dusk qualities of my taintilator seat when the ole hoss pooped out on me on the interstate.  :cowpoop:

I had found a gap in the rain and was humming along at 75 mph indicated for an hour, when I looked down and realized I had slowed to 65 and the throttle was wide open.  No Bueno.

I got off and limped another 20 or 30 miles to town with performance decreasing by the minute.  Anything about 4,000 RPMs and it would wig out, also worse heading up hills.  The final hill into town it started bucking, and I waited for a ride home and collected it the next day with a trailer.

Still starts fine and sounds fine under no load, and I rode it  into the shed under it's own power in 1st gear.

The only other symptoms were a kind of brief fluttering power loss that cleared up when warm while I was riding a few weeks earlier.  This wasn't a flutter thought, this was more like anemia and bogging down if I tried to get above 4,000 RPM.   

Any thoughts or game plans? 
  • Brooklyn
  • '90 K75 - '93 K1100RS (and a tw200)

Offline Scott_

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Re: power loss whack - '90 K75
« Reply #1 on: June 17, 2019, 08:57:45 PM »
When was the last time you checked the valve clearances.....
I overlooked it when I acquired my 1st brick and I burned a couple of exhaust valves shortly there after........
If you can, you might want to run a compression test.

When mine went out on me, I was cruising same as you, 65+ and then just a slow steady decline and eventually no power. Barely enough to get me home 60 miles with just 2 cylinders and no more than 3rd gear.....
When I was diagnosing it I thought it might have been the head gasket as it was #2 and #3 that were out. Mechanic pulled the head and found the bad valves instead.
YMMV
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1997 K1100LT 0302488
1995 K1100LT 0302044
Garmin StreetPilot 2820
Garmin Zumo 550
"One who does not ask questions is ashamed to learn" Danish proverb

Offline Laitch

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Re: power loss whack - '90 K75
« Reply #2 on: June 17, 2019, 09:17:08 PM »
A compression test will indicate a gross failure like a burned valve and is a relatively quick test to perform. Before you do that, look into the fuel tank for disconnected lines and check fuel flow at the rail.
  • Along the Ridley in Vermont.
  • 1995 K75 72,000 miles
I wept because I had no radials until I met a man who had no splines.
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Offline Scott_

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Re: power loss whack - '90 K75
« Reply #3 on: June 17, 2019, 09:43:30 PM »
Then there is the fuel filter...... How old is it.
  • My Garage
Ride safe.


1997 K1100LT 0302488
1995 K1100LT 0302044
Garmin StreetPilot 2820
Garmin Zumo 550
"One who does not ask questions is ashamed to learn" Danish proverb

Offline herseyb

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Re: power loss whack - '90 K75
« Reply #4 on: June 18, 2019, 04:43:37 PM »
Hmmm,

  any recommendations for a fuel pressure tester and a compression tester?  Price/reviews seem to be all over the board.  I'd rather spend $20 than $100, but I'd rather get one that is going to actually work even more.
  • Brooklyn
  • '90 K75 - '93 K1100RS (and a tw200)

Online Martin

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Re: power loss whack - '90 K75
« Reply #5 on: June 18, 2019, 05:09:57 PM »
Fuel pressure tester is pretty easy a gauge and a bit of plumbing. My gauge was salvaged of a compressor regulator but you should be able to pick up a new one for under $20.00.  I normally tap into the return line. Harbor Freight should have a suitable compression gauge.
Regards Martin.


* FPR Test Gauge 1.jpg (56.53 kB . 768x576 - viewed 113 times)
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline Laitch

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Re: power loss whack - '90 K75
« Reply #6 on: June 18, 2019, 06:33:26 PM »
any recommendations for a fuel pressure tester and a compression tester? 
You're not telling us much. Did you disconnect the fuel line to the rail, press the starter and have moths fly out? Looked into the tank for fish or crabs clogging lines? Don't go all gizmoey yet. One test at a time.
  • Along the Ridley in Vermont.
  • 1995 K75 72,000 miles
I wept because I had no radials until I met a man who had no splines.
https://tinyurl.com/RillRider

Offline caveman

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Re: power loss whack - '90 K75
« Reply #7 on: June 18, 2019, 07:52:34 PM »
If you pinch off the outlet hose your pump should scream instead of whine. It's not high tek but you should have something already to do the job. Also you may find a split filter or hose in the tank.
I will send you a PM
  • Kennerdell, PA.
  • 87 K100RT, 88 K100LT

Offline herseyb

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Re: power loss whack - '90 K75
« Reply #8 on: August 08, 2019, 09:22:07 PM »
After a nice good ride on k1100 I finally balled up  to follow Laitch's simple game plan of visual inspection of the tank vs. googling while at work.

OMFG THERE IS GREEN PEALING SOMETHING GOING ON!!!!    Plus chalky bullshit failing my cap seal.

WTFBBQ I think there might actually be crabs.    Cheezus...  what n the hell... 

 :dungee: :dungee: :dungee: :dungee:


* TankWHACK.jpg (41.65 kB . 768x432 - viewed 65 times)
  • Brooklyn
  • '90 K75 - '93 K1100RS (and a tw200)

Offline The Mighty Gryphon

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Re: power loss whack - '90 K75
« Reply #9 on: August 08, 2019, 09:35:17 PM »
Yikes!!!!  Is that your tank?  What have you been running in your Motobrick?
  • In my garage in Marilla, NY
  • '94 K75RT Mystic Red, '91K100RS White/Blue, '89 K100RS Special edition White/Blue
Current:
'94 K75RT "Ilsa, She Wolf of the SS"
'91 K100RS "Moby Brick Too
'89 K100RS SE

Offline herseyb

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Re: power loss whack - '90 K75
« Reply #10 on: August 08, 2019, 09:44:08 PM »
swear to god, you'd think i'm running uranium or something.

I wonder if it is failing tank liner?  Northern fuel tank liner says water will break it down, and it can stain gas green.  I am the 3rd owner so I don't know the full history.   That's stretching it though because it's been living inside - so unless I get bum gas...   I really dunno. 

Can I pressure wash the inside of the tank if I pull the pump and hoses out?



  • Brooklyn
  • '90 K75 - '93 K1100RS (and a tw200)

Offline herseyb

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Re: power loss whack - '90 K75
« Reply #11 on: August 08, 2019, 10:11:21 PM »
Rodger Dodger.  I will put it in a barrel with some blankets and make the barn cats roll it around the yard to help agitate the vinegar 'n' rocks.  I did see he made that tank purty!

  • Brooklyn
  • '90 K75 - '93 K1100RS (and a tw200)

Offline volador

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Re: power loss whack - '90 K75
« Reply #12 on: August 08, 2019, 10:19:49 PM »
If the above does not work try MEK, acetone or lacquer thinner for removal of the lining.

Tank liner in a can like Red-Kote "For clean-up use methyl ethyl ketone, acetone or a quality lacquer thinner with no alcohol in it."

Mask off your paint before using any of these products
  • NYC
  • 1991 K100RS 1993 K75S ABS
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Offline Scott_

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Re: power loss whack - '90 K75
« Reply #13 on: August 08, 2019, 11:01:46 PM »
Almost makes one wonder WHY it was sprayed with liner in the 1st place....... What's to be found after it's cleaned out, corrosion holes in the bottom seam? 
  • My Garage
Ride safe.


1997 K1100LT 0302488
1995 K1100LT 0302044
Garmin StreetPilot 2820
Garmin Zumo 550
"One who does not ask questions is ashamed to learn" Danish proverb

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