Author Topic: My K75 restoration  (Read 9054 times)

Offline frankenduck

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Re: My K75 restoration
« Reply #25 on: June 07, 2021, 11:00:52 AM »
Yeah, that does not get rid of the air totally, but it actually does speed up the bleeding process, it lets fluid make its way down the lines so that when you do a normal bleeding procedure it 's a lot less air to pull out.

You're just wasting brake fluid.  The air gets out of the system by bubbling out at the top, not by being pulled or pushed downward. (Brake fluid is a liquid that weighs more than air.)
Once I had a Collie pup. Dug a hole and covered him up. Now I sit there by the hour. Waiting for a Collie-flower.
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Offline The Mighty Gryphon

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Re: My K75 restoration
« Reply #26 on: June 07, 2021, 05:59:47 PM »
I learned the hard way that the bubbles you see vacuum bleeding are the air leaking past the threads of the bleeder nipple.  I've pulled a couple gallons of good brake fluid through the brake systems of my bikes waiting for those bubbles to stop.
  • 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 mcgyver74

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Re: My K75 restoration
« Reply #27 on: July 03, 2021, 10:29:59 PM »
So it's been a while since I updated (this thing keeps getting in the way called life LOL)  but today I got some more work done on the Brick.

Today was all about tackling the fuel system.  The intake manifolds and throttle body boots were dry rotted to heck and back (and It helped me do some more cleaning,  wow this thing is filthy)

So first I popped the clamps and removed the throttle body and box... 



Sheesh that's a dirty birdy..  Need to protect those throttle bodies and get some cleaning done




This is the main reason I am doing this.. The bike has been acting like it's lean (Stumbling off idle, had a hell of a stutter when revving) and the intake boots were dry rotted and cracked to hell.  The intake manifolds weren't cracked (Not shown) but they were hard as a rock..



Let's clean some parts, I am reusing these clamps but not like this LOL



Ah that's better


Ugh even the airbox is grotty.. :(



Ok let's clean up the mating surfaces and get the intake manifolds on



2 out of 3 done (I didn't get an after pic...sorry LOL)


Brandy new parts :)


Ok the throttle bodies need some love too



All back together :)







Even though I will have to pull it off when I install all the new bodywork I got, this windscreen has been bugging me for AGES, it's cracked and crazed.   New one is on



Looking sharp!




So she is all back together and it doesn't sputter anymore, I also replaced the hose going from the TB to the fuel pressure regulator because while it was still sealed, it's starting to turn to goo....Used some fuel hose for that instead of the BMW part with the spring...  so all done for today... except i need to pull the airbox off again because I am a bonehead  177381,  Something is wedged in the wrong place and I cannot open the throttle more then an inch...(Both at the grip and at the TB) Need to see what's hanging it up.... but I can get it to go from idle to 1500 and it's nice and schmooth!! 


Of course while warning up, she decided to spring a coolant leak from the lower rad hose, but  as those hoses are all 30 years old I cannot be too upset,   next to order all new hoses.   More to come!! :)


  • Jersey City NJ
  • 1990 K75S
Jersey City NJ
1990 K75S

Offline The Mighty Gryphon

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Re: My K75 restoration
« Reply #28 on: July 04, 2021, 09:52:16 AM »
Nice work!  May I suggest getting a bottle of S100 motorcycle cleaner and a bunch of those sticks with spongeballs on the end at the dollar store.  Seal up the intakes and pull as much of the body work as possible(especially the tank and battery) and go to it with the S100 a couple times.  In an hour or so your bike will look a thousand times better and be infinitely more pleasant to work on.
  • 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 mcgyver74

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Re: My K75 restoration
« Reply #29 on: July 04, 2021, 11:53:19 AM »
Yeah I plan to give it a wash, wanted to get the intake boots changed before I did since they were all cracked and I didn't want water getting into the intake.  Will look into S100 (Never thought of it, was gonna use simple green :) ) )

I assume I can just seal the plastic box on top of the throttle bodies and i don't actually need to pull those clamps again?
  • Jersey City NJ
  • 1990 K75S
Jersey City NJ
1990 K75S

Offline John Lang

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Re: My K75 restoration
« Reply #30 on: July 05, 2021, 07:22:25 AM »
A young feller offered to clean up my nearly opaque windshield. I accepted with little confidence the 34-year-old plastic could be redeemed. He proved me wrong.
  • Ottawa, ON Canada
  • 1987 K75C

Offline Laitch

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Re: My K75 restoration
« Reply #31 on: July 05, 2021, 07:46:26 AM »
I assume I can just seal the plastic box on top of the throttle bodies and i don't actually need to pull those clamps again?
Sure thing. What shouldn't be done is wash this thing with high pressure if electrical components or connectors are present  because water is likely to penetrate them and cause trouble later on.
  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

Offline mcgyver74

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Re: My K75 restoration
« Reply #32 on: July 06, 2021, 08:31:49 PM »
I plan to use a garden hose,  should be low pressure enough :)
  • Jersey City NJ
  • 1990 K75S
Jersey City NJ
1990 K75S

Offline TommyT

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Re: My K75 restoration
« Reply #33 on: July 07, 2021, 04:34:28 PM »
A young feller offered to clean up my nearly opaque windshield. I accepted with little confidence the 34-year-old plastic could be redeemed. He proved me wrong.
Do you know how he did it? I have windshield like yours before cleaning, I was wondering if the car headlight cleaning up kits would work on the BMW windshields.
  • Olive NY
  • 1990 K75RT, 1991 K100 16V(2), 1986 K75 "T"

Offline mw074

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Re: My K75 restoration
« Reply #34 on: July 07, 2021, 05:08:39 PM »
To clean up the windscreen, I use Novus plastic polish. It is available at Harley shops.
  • Michigan

Offline John Lang

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Re: My K75 restoration
« Reply #35 on: July 07, 2021, 09:20:41 PM »
I have asked him what he used. Will revert.
  • Ottawa, ON Canada
  • 1987 K75C

Offline mcgyver74

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Re: My K75 restoration
« Reply #36 on: July 07, 2021, 09:24:15 PM »
To restore it, you can probably use something like the 3M headlight restoration system,  I was going to do that but mine was cracked and broken, wasn't worth saving :(

But something like this should work

  • Jersey City NJ
  • 1990 K75S
Jersey City NJ
1990 K75S

Offline The Mighty Gryphon

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Re: My K75 restoration
« Reply #37 on: July 07, 2021, 11:21:26 PM »
Those kits only work if the problem is the clear coat that is applied to the plexiglass to make it "anti-scratch".

If a windshield has been cleaned with Windex or some other cleaner with ammonia there is micro crazing that goes into the plastic deeper than polishing compounds can reach.  I've had two windshields with this problem, and they were impossible to correct.  You can make them a little better, but they will never look good.
  • 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 John Lang

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Re: My K75 restoration
« Reply #38 on: July 08, 2021, 06:43:01 PM »
Reply from the gentleman who cleaned up my windshield. He uses the same process and products for headlight covers.

"The process steps and products I used for your bike windshield are listed below in order.

Step 1) clean surface with 50/50 water and isopropyl alcohol

Step 2) wet sanding (3M sandpaper)
        - 800 grit
        - 1200 grit
        - 1500 grit
        - 2000 grit

Step 3) Cutting and polishing stage
Product (Chemical Guys V Line for cutting, polishing and removing scratches
- compound cutting with cutting pad
- polishing compound with polishing pad
- finishing compound with finishing pad

Step 4) Clear coat stage:
- applied Meguairs Plastix clear coat and let dry or 1-2 hrs"


  • Ottawa, ON Canada
  • 1987 K75C

Offline frankenduck

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Re: My K75 restoration
« Reply #39 on: July 08, 2021, 09:53:05 PM »
Step 4) Clear coat stage:
- applied Meguairs Plastix clear coat and let dry or 1-2 hrs"

PlastX does not "clear coat" anything. It's a cleaner and polisher. Once you wipe it off it is gone. Nothing is left behind.

And it says right on the bottle that it should be used on small areas at a time and wiped off before it dries.
Once I had a Collie pup. Dug a hole and covered him up. Now I sit there by the hour. Waiting for a Collie-flower.
New to K bikes? Click here.
K Bike Maintenance & Mods: Click here.
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Offline TommyT

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Re: My K75 restoration
« Reply #40 on: July 09, 2021, 10:13:51 AM »
Reply from the gentleman who cleaned up my windshield. He uses the same process and products for headlight covers.

"The process steps and products I used for your bike windshield are listed below in order.

Step 1) clean surface with 50/50 water and isopropyl alcohol

Step 2) wet sanding (3M sandpaper)
        - 800 grit
        - 1200 grit
        - 1500 grit
        - 2000 grit

Step 3) Cutting and polishing stage
Product (Chemical Guys V Line for cutting, polishing and removing scratches
- compound cutting with cutting pad
- polishing compound with polishing pad
- finishing compound with finishing pad

Step 4) Clear coat stage:
- applied Meguairs Plastix clear coat and let dry or 1-2 hrs"

Thanks. I have the 3M kit and did my car headlight covers successfully.  Since I plenty of the polish and pads left I will try it first on a small section my K bike.
  • Olive NY
  • 1990 K75RT, 1991 K100 16V(2), 1986 K75 "T"

Offline stokester

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Re: My K75 restoration
« Reply #41 on: July 09, 2021, 08:11:07 PM »
When I worked at a Chevy dealership we had the "professional" kits for revitalizing headlights.
It included compounds and materials for wet sanding to remove the discolored outer layer leaving a hazy surface.  A spray with the final coating and use of a UV lamp or parked outside on a sunny day for curing cleared it up nicely.  Rather pricey for the kit and labor.

I used one of the commercial kits on my daughter's car which cleaned it up but did not last.  I think this was because there was no clear-coat to finish the treatment.  Ended up buying some aftermarket.
  • Yorktown Virginia
  • '94 K75S Dakar Yellow - '93 K75S Seiden Blau - '91 R100RT Bermuda Blue- '78 R100S Smoke Red

Offline frankenduck

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Re: My K75 restoration
« Reply #42 on: July 09, 2021, 11:19:13 PM »
For my car's headlights I just bought cheap ChiCom knock-offs from Rock Auto.  Only took a few minutes of my labor to swap them in. Perfectly clear for the last five years. (And they work even better since I replaced the OEM bulbs with a $30 set of LED headlight bulbs from Amazon.)
Once I had a Collie pup. Dug a hole and covered him up. Now I sit there by the hour. Waiting for a Collie-flower.
New to K bikes? Click here.
K Bike Maintenance & Mods: Click here.
Buy parts here.

Offline mcgyver74

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Re: My K75 restoration
« Reply #43 on: July 19, 2021, 12:39:31 PM »
So I did some more work on the K this weekend, didn't get a lot done due to time constraints but I was able to confirm my throttle blockage was due to the clamps on the intake runners,   adjusted them and the throttle moves freely now.

Had some weirdness when I started her up,  it was only running on 2 cylinders (confirmed this with a power balance test)  Odd thing is I could not find a reason,  I pulled the coils and cleaned the terminals (and grounds), no change. THen I swapped the plugs from number 3 to number 2 and visa versa and then for some reason all 3 holes started working...   Guess I will look into a set of wires.

One odd thing,  the bike is smooth from 1k upwards, but if I go to roll on the throttle, there is a hesitation coming off idle, I seem to recall the bike always had that, but it doesn't seem right to me.   Any suggestions where to check? :)  other then that I ran her for a good while until I confirmed the Rad fan works


Next up is the cooling system, I finally have all new parts so I can refresh  that, hoping to tackle it next weekend,  can anyone point me to where the bleeder screw for the cooling system is? Also is there a trick to getting that hose that runs through the crankcase out?

TIA!!!
  • Jersey City NJ
  • 1990 K75S
Jersey City NJ
1990 K75S

Offline Laitch

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Re: My K75 restoration
« Reply #44 on: July 19, 2021, 01:09:56 PM »
. . . I go to roll on the throttle, there is a hesitation coming off idle, I seem to recall the bike always had that, but it doesn't seem right to me.   Any suggestions where to check? :) 

can anyone point me to where the bleeder screw for the cooling system is? Also is there a trick to getting that hose that runs through the crankcase out?
I don't accept TIA; only TATF is accepted.  :laughing4-giggles:

First, I'll let a revered graybeard explain the hesitation, here.

Next, There is no bleeder screw. What would be your goal if you found one?  If you're trying to drain the cooling system remove the radiator filler cap, then either remove the drain plug at the bottom of the combo pump, or remove the coolant hose from the top of the combo pump. If you believe you have air bubles in the system, there's a procedure for dealing with that.

To remove the hose, warm up the hose, soap it, fold it if you're able then slide it out.
  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

Offline mcgyver74

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Re: My K75 restoration
« Reply #45 on: July 19, 2021, 01:15:22 PM »
Thanks,  the bleeder I was asking about was for getting the air out of the system

My plan was to pop the lower rad hose to drain it,  then remove all the hoses so I can get to the thermostat housing,  change that then re-assemble and fill.  I've had other bikes that had a location where you could bleed the air out (mostly) when doing a coolant change...   :)
  • Jersey City NJ
  • 1990 K75S
Jersey City NJ
1990 K75S

Offline Laitch

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Re: My K75 restoration
« Reply #46 on: July 19, 2021, 01:22:20 PM »
I've had other bikes that had a location where you could bleed the air out (mostly) when doing a coolant change...   :)
Mamy of us are familiar with those but you're in Brick territory now. Instructions for filling with coolant and removing air are in the 2V service manual in the Service Manual section of the Technical Directory on the Homepage.
  • Along the Ridley in Vermont.
  • 1995 K75 89,000 miles

Offline frankenduck

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Re: My K75 restoration
« Reply #47 on: July 19, 2021, 01:31:49 PM »
My plan was to pop the lower rad hose to drain it,  then remove all the hoses so I can get to the thermostat housing,  change that then re-assemble and fill.  I've had other bikes that had a location where you could bleed the air out (mostly) when doing a coolant change...   :)

There's no need to do that. The radiator cap "blows" at 1.0 bar when it overheats.  When the system is cooling down the radiator cap opens in the other direction at -0.1 bar to draw in coolant from the coolant reservoir. That's why the coolant reservoir exists.
Once I had a Collie pup. Dug a hole and covered him up. Now I sit there by the hour. Waiting for a Collie-flower.
New to K bikes? Click here.
K Bike Maintenance & Mods: Click here.
Buy parts here.

Offline mcgyver74

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Re: My K75 restoration
« Reply #48 on: July 19, 2021, 01:35:31 PM »
Thanks,  I have a new cap as well as thermostat and all hoses.  The service manual doesnt seem to cover the hose replacement but that looks kinda easy.

As for the bleeding, it says to crank the starter while burping the lower hose.   Wasn't sure if there was more :)
  • Jersey City NJ
  • 1990 K75S
Jersey City NJ
1990 K75S

Offline frankenduck

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Re: My K75 restoration
« Reply #49 on: July 19, 2021, 01:39:39 PM »
One odd thing,  the bike is smooth from 1k upwards, but if I go to roll on the throttle, there is a hesitation coming off idle, I seem to recall the bike always had that, but it doesn't seem right to me.

Set the idle at 1100+ and most of the hesitation goes away. That's how I have all of my K75s set up.
Once I had a Collie pup. Dug a hole and covered him up. Now I sit there by the hour. Waiting for a Collie-flower.
New to K bikes? Click here.
K Bike Maintenance & Mods: Click here.
Buy parts here.

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