Author Topic: K100 fuel pump changes  (Read 390 times)

Offline BlueK11LT

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K100 fuel pump changes
« on: August 07, 2019, 01:09:46 PM »
A friend has aqquired a 1984 original version,naked K100 which has been parked up without being started for nearly 20 years.
The tank was not drained when the bike was laid up resulting in lots of gooey varnish and sticky perished tar - like rubber from the fuel pump holder,the inside of the tank should be cleaned out without too many problems and the whole fuel pump,holder,gauze,hoses and filter assembly are going to be replaced with new items.
The fuel pump holder is the earlier 6 nut/stud type which does not seem easily obtainable now,so we have decided to go for the later 1985 onwards 5 nut/stud holder
Am i correct that there should be no problems with this?
Iam also a bit puzzled why the gauze filter on the bottom of the pump was changed from 85,was this because the later gauze filter can only be used in conjunction with the later holder? or was there some change with the pump itself from 85 on? nessecatating the change to the gauze filter?
Iam under the impression that all the K100/75 fuel pumps were the same 52mm thickness item that was used until it was changed to a thinner item in the early 90's.
Also any hints about the fuel injectors before we try to start the engine?are the likely to be gummed up with stale fuel/residue etc?
Thanks,
Dave
  • North East England
  • 1997 K1100LT,1977 Kawasaki Z650B1,1991 Honda ST1100

Offline volador

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Re: K100 fuel pump changes
« Reply #1 on: August 08, 2019, 01:31:47 PM »
There are no differences in mounting either the 6 stud or the 5 stud fuel damper with retaining ring (except the lack of flange material).
Both versions snap into the fuel pump mounting base the same.

The post '85 version of the pre-filter screen has a "anti-cavitation" tubing/port which connects to the fuel return line inside fuel tank via a rubber hose.
Many omit this rubber hose connection with out any ill effects.

Soak the fuel injectors in lacquer thinner or denatured alcohol. Many videos on injector cleaning.
Replace with Viton O-rings from Tills.de
Good Day
  • NYC
  • 1991 K100RS 1993 K75S ABS
FIVE BOROUGHS SISYPHEAN SOCIETY "WHEN LIFE THROWS YOU A CURVE... LEAN INTO IT"

Offline Laitch

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Re: K100 fuel pump changes
« Reply #2 on: August 08, 2019, 02:12:54 PM »
The post '85 version of the pre-filter screen has a "anti-cavitation" tubing/port which connects to the fuel return line inside fuel tank via a rubber hose.
That isn't the fuel return line to which the hose from the pump filter basket is connected; no return fuel comes from that port. It is a port connected to the vent chamber near the tank's ceiling for the purpose of diverting air from entering the fuel pump. From the chamber, air and vapor are vented to the outside. In the later models, the fuel return line outlet is above the vent chamber and fuel spills from it into the tank. In earlier models, returning fuel directly enters into the tank from a port in the floor of the tank.
  • Along the Ridley in Vermont.
  • 1995 K75T 72,000 miles
I wept because I had no radials until I met a man who had no splines.
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Offline volador

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Re: K100 fuel pump changes
« Reply #3 on: August 08, 2019, 03:04:22 PM »
That isn't the fuel return line to which the hose from the pump filter basket is connected; no return fuel comes from that port.
I think you got your tubes crossed
I'll go have an afternoon profiterole and espresso while you sort things out  :laughing4-giggles:
  • NYC
  • 1991 K100RS 1993 K75S ABS
FIVE BOROUGHS SISYPHEAN SOCIETY "WHEN LIFE THROWS YOU A CURVE... LEAN INTO IT"

Offline Laitch

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Re: K100 fuel pump changes
« Reply #4 on: August 08, 2019, 03:08:23 PM »
I'll go have an afternoon profiterole and espresso while you sort things out  :laughing4-giggles:
I endorse that! Maybe they'll stimulate your understanding.  :popcorm
  • Along the Ridley in Vermont.
  • 1995 K75T 72,000 miles
I wept because I had no radials until I met a man who had no splines.
http://www.motobrick.com/index.php/topic,296.msg53303.html#msg53303

Offline The Mighty Gryphon

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Re: K100 fuel pump changes
« Reply #5 on: August 08, 2019, 05:02:59 PM »
I believe Volador is correct.  The return line connects to the barb on the screen basket to feed previously filtered fuel returning from the rail to the base of the fuel pump to prevent cavitation. 

I suspect a side benefit is that it helps prevent hot fuel from mixing with that which is in the tank, possibly keeping the tank a little cooler.
  • In my garage in Marilla, NY
  • '94 K75RT Mystic Red, '91K100RS White/Blue
Current:
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'91 K100RS "Moby Brick Too

Offline Laitch

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Re: K100 fuel pump changes
« Reply #6 on: August 08, 2019, 06:44:57 PM »
I believe Volador is correct.  The return line connects to the barb on the screen basket to feed previously filtered fuel returning from the rail to the base of the fuel pump to prevent cavitation. 

I suspect a side benefit is that it helps prevent hot fuel from mixing with that which is in the tank, possibly keeping the tank a little cooler.
You shouldn't need to believe that. You should see fuel pouring from that. Have you?
  • Along the Ridley in Vermont.
  • 1995 K75T 72,000 miles
I wept because I had no radials until I met a man who had no splines.
http://www.motobrick.com/index.php/topic,296.msg53303.html#msg53303

Offline volador

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Re: K100 fuel pump changes
« Reply #7 on: August 08, 2019, 07:00:33 PM »
I endorse that! Maybe they'll stimulate your understanding. 

I'll be looking forward to your next webinar on the "K Fuel Tank" pre & post '85

I believe Volador is correct. 

One of each for TMG

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  • NYC
  • 1991 K100RS 1993 K75S ABS
FIVE BOROUGHS SISYPHEAN SOCIETY "WHEN LIFE THROWS YOU A CURVE... LEAN INTO IT"

Offline Laitch

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Re: K100 fuel pump changes
« Reply #8 on: August 08, 2019, 07:59:46 PM »
I'll be looking forward to your next webinar on the "K Fuel Tank" pre & post '85
It's already happened. It's also obvious you didn't attend. You ought to remove your moto's fuel tank cap assembly, remove that hose—if it's still there—start the engine and watch what doesn't happen. Borrow a phillips screwdriver from one of your admirers, if you don't have one yet.
  • Along the Ridley in Vermont.
  • 1995 K75T 72,000 miles
I wept because I had no radials until I met a man who had no splines.
http://www.motobrick.com/index.php/topic,296.msg53303.html#msg53303

Offline volador

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Re: K100 fuel pump changes
« Reply #9 on: August 08, 2019, 09:36:13 PM »
Borrow a phillips screwdriver from one of your admirers, if you don't have one yet.
Leave them out of this, they're not the mechanical type.
I have a Cornwall roll box with the latest and greatest in screwdrivers, philips, wrenchs and implemants.
  • NYC
  • 1991 K100RS 1993 K75S ABS
FIVE BOROUGHS SISYPHEAN SOCIETY "WHEN LIFE THROWS YOU A CURVE... LEAN INTO IT"

Offline daveson

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Re: K100 fuel pump changes
« Reply #10 on: August 09, 2019, 04:35:13 AM »
After looking at internal tank photos on the net, I made the mistake of thinking the barb at the left of the filler cap (to the vent chamber) was a fuel return pipe. I found the description from Laitch, maybe a year ago,  was right,  after looking inside my tank.

That barb, and the pump filter barb, were 6mm. They were joined by a 6mm hose. The fuel return barb and hose were 8mm. I discarded the 6mm hose as it was softer than liquorice. I replaced the 8mm return hose as it was so brittle that if you even thought about bending the hose,  it would crack in anticipation.

If the 6mm hose is missing, it would be an easy mistake to connect the 8mm return hose to the 6mm filter barb,  but I would bet my bottom dollar it didn't leave the factory like that.

I spose it doesn't matter why the changes were made, just get what suits your brick.

I will guess the injectors are blocked. There are posts here about cleaning them, and posts for alternative parts. I ended up getting injectors at a car breakers from an 80's BMW.
  • Victoria, Australia
  • Current;'86 K100RT Past; '97 Yamaha V Star 650 Yamaha V Star

Offline volador

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Re: K100 fuel pump changes
« Reply #11 on: August 09, 2019, 10:21:38 AM »
^+1
Add at your own will depending on your moto's year/model or tank version
 
16 018 94 (2630R) Fuel Pump Noise - K Models Revised Service Bulletin
  • NYC
  • 1991 K100RS 1993 K75S ABS
FIVE BOROUGHS SISYPHEAN SOCIETY "WHEN LIFE THROWS YOU A CURVE... LEAN INTO IT"

Offline daveson

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Re: K100 fuel pump changes
« Reply #12 on: August 09, 2019, 08:30:13 PM »
That bulletin isn't relevant to the k100 or Blue's questions, nor was my last reply much so,  I spose.

I have five bricks from '84 to '89. All the holders have six bolts,  and all pumps 52mm. I have two filter types,  one has a 6mm barb, the other doesn't. Since your getting all these parts at the same time, it should all be compatible. My guess would have been that the later model doesn't have the barb,  as it works fine without it.
  • Victoria, Australia
  • Current;'86 K100RT Past; '97 Yamaha V Star 650 Yamaha V Star

Offline volador

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Re: K100 fuel pump changes
« Reply #13 on: August 09, 2019, 08:39:55 PM »
That bulletin isn't relevant to the k100 or Blue's questions

I guess I strayed off topic. Just put it out there since related to the fuel return line

The later model comes with the barb 16121455126



Back to Blue's friends '84 K100

Upgrade to the 43mm fuel pump with strainer and corresponding sized parts if you are changing all. Getting away from the fragile plastic pre-filter



Or you can get a 52mm pre-filter in metal from Tills.de




You have your choice
Good Day
  • NYC
  • 1991 K100RS 1993 K75S ABS
FIVE BOROUGHS SISYPHEAN SOCIETY "WHEN LIFE THROWS YOU A CURVE... LEAN INTO IT"

Offline daveson

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Re: K100 fuel pump changes
« Reply #14 on: August 10, 2019, 12:59:22 AM »
Attempt two at adding photo.

A 6mm barb, 6mm short piece of hose and 8mm hose, its more noticeable in a photo.

I spose the barb is the reason for the two types. the barbed one is also deeper.
  • Victoria, Australia
  • Current;'86 K100RT Past; '97 Yamaha V Star 650 Yamaha V Star

Offline BlueK11LT

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Re: K100 fuel pump changes
« Reply #15 on: August 10, 2019, 02:43:41 AM »
thanks for the replies,things are quite a bit clarified for me now.
I was not aware that the later 43mm pump could replace the earlier 52mm one,but we have already ordered the post 85 mounting parts,gauze,filter and fuel piping from Motorworks BMW,and a quality german made pattern pump from ebay at one third of the price of the original Bosch item
  • North East England
  • 1997 K1100LT,1977 Kawasaki Z650B1,1991 Honda ST1100

Offline Laitch

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Re: K100 fuel pump changes
« Reply #16 on: August 10, 2019, 07:58:11 AM »
thanks for the replies,things are quite a bit clarified for me now.
I was not aware that the later 43mm pump could replace the earlier 52mm one,but we have already ordered the post 85 mounting parts,gauze,filter and fuel piping from Motorworks BMW,and a quality german made pattern pump from ebay at one third of the price of the original Bosch item
To summarize where you are, BlueK11LT, if you purchased a 52mm pump and filter basket with a vent hose fitting, connecting the vent hose from the basket to the vent port on the tank's ceiling is optional. It adds a level of protection to keep air bubbles from mixing then entering the pump where their presence might cause damage. That's a condition that might happen if the tank is at an extremely low fuel level but some of us have been running without that hose and no incidents have occurred.

If you purchased a 43mm pump and fuel sock, a vent port descending from the tank's ceiling won't be connected to anything; it will simply serve as an additional vent for tank pressure into the vapor collector that will then be evacuated from the tank via a port beneath the tank.
  • Along the Ridley in Vermont.
  • 1995 K75T 72,000 miles
I wept because I had no radials until I met a man who had no splines.
http://www.motobrick.com/index.php/topic,296.msg53303.html#msg53303

Offline volador

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Re: K100 fuel pump changes
« Reply #17 on: August 10, 2019, 10:24:26 PM »
I'll be looking forward to your next webinar on the "K Fuel Tank" pre & post '85

It's already happened. It's also obvious you didn't attend.

To summarize the outcome, Professor, guessing I'm not the only one who didn't attend your "Petrol Tank" webinar.
BlueK11LT and company experienced what reads like a OMFG K100 rolling fireball in the garage. Luckily no one was injured.
Maybe you can rebroadcast for MOEs to avoid future mishaps
  • NYC
  • 1991 K100RS 1993 K75S ABS
FIVE BOROUGHS SISYPHEAN SOCIETY "WHEN LIFE THROWS YOU A CURVE... LEAN INTO IT"

Offline Laitch

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Re: K100 fuel pump changes
« Reply #18 on: August 10, 2019, 10:29:14 PM »
Maybe you can rebroadcast for MOEs to avoid future mishaps
Maybe you should found a Five Boroughs Sisyphean Society and appoint yourself its president.
  • Along the Ridley in Vermont.
  • 1995 K75T 72,000 miles
I wept because I had no radials until I met a man who had no splines.
http://www.motobrick.com/index.php/topic,296.msg53303.html#msg53303

Offline volador

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Re: K100 fuel pump changes
« Reply #19 on: August 10, 2019, 11:54:51 PM »
Maybe you should found a Five Boroughs Sisyphean Society and appoint yourself its president.

That's some heavy chit, Professor. I'm going to have to reread some Homer. "D'oh!"
  • NYC
  • 1991 K100RS 1993 K75S ABS
FIVE BOROUGHS SISYPHEAN SOCIETY "WHEN LIFE THROWS YOU A CURVE... LEAN INTO IT"

Offline Laitch

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Re: K100 fuel pump changes
« Reply #20 on: August 11, 2019, 06:15:30 AM »
Read the Cliff Notes version. It's lighter.
  • Along the Ridley in Vermont.
  • 1995 K75T 72,000 miles
I wept because I had no radials until I met a man who had no splines.
http://www.motobrick.com/index.php/topic,296.msg53303.html#msg53303

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