Author Topic: 1992 K75RT Refresh/recommissioning, Near Atlanta GA  (Read 268 times)

Offline Georgia_Rider

  • Curious
  • Posts: 3
1992 K75RT Refresh/recommissioning, Near Atlanta GA
« on: January 02, 2019, 10:43:15 PM »
Refreshing 1992 K75RT

Bear with me, Iím a newbie.

Iím writing to ask for your comments regarding the best sequence of evaluating this bike before we begin any re-commissioning. Budget is a consideration as weíre paying a couple of college tuitions for the next few years. I donít want to jump into a money pit, but I do think this could be a nice, reliable bike with a deliberate plan to bring her back. We didnít compression test this bike at time of purchase and it hasnít run since 2013.

I recently purchased this bike locally from an electrical engineer who owned a few other newer BMW bikes. This one kept getting moved around in his garage until it was moved out. My timing was good and I want to believe it has great potential.

My thought it would be a great 57 year old dad (me) and 22 year old son project to make it roadworthy and a keeper. My son is more mechanically experienced from his enduro riding, but we both recognize this is bike a whole different animal.

The price seemed very reasonable for a non running K75RT,  it shows 86K miles with little surface rust (NC and GA bike) only on exhaust I think, is 99% complete bike, and I am now the 3rd Owner. 2nd Previous Owner (PO) bought it in 2007 with 65K miles, rode it until 2013 including several cross-country trips when he moved into newer BMW models. It has not run since 2013, PO replaced the transmission and new clutch plates in 2011 for his last journey on it to west coast. 

The last PO believed the problem was due to his negligence of leaving fuel in the tank and the purchase included a new fuel pump in a box. I do think itís odd that transmission was replaced but PO didnít lube splines. New clutch plates were installed at same time. I hope the first owner did something to the splines before it was sold at 65k miles to 2nd Owner. All manuals and side bags are included, Tupperware is crack free and hole free (wow!) except where PO had air wings mounted. Dealer maintenance was not done after the 8k mile interval and all maintenance since was done by POís, I hope. I believe it was, given the fluids look good and it was a cross-country bike.

Of course, it needs tires (2009), hoses replaced, and the list goes on, but weíre just trying to see if it runs to evaluate if we continue moving forward.

Neither my son nor I are familiar with BMWs, so we know this is going to be a learning curve. On line resources are great and we're learning about parts places. Suggestions welcomed.

First things first; we removed the tank and found the petrol sensor eaten up (resembles an artifact from the Titanic recovery site) and needs replacement (PN 62162305558). Inside of tank looks good. Since we bought it without checking compression, I think this initial sequence is to;

1. Charge/replace battery,
2. Install provided fuel pump,
3. Order and install fuel gauge sensor (are there any better places than euromotoelectrics for these? https://www.euromotoelectrics.com/product-p/flf-565.htm )
4. Change spark plugs, engine oil/oil filter, clean/replace air filter and attempt to turnover/crank.

If it does run, then we evaluate splines since I read they can be costly and do maintenance on them. At this point, I think we'd be in same zone if it runs. Then, replace all other fluids and lines for clutch, brakes, etc. And then we continue with tires, connectors, etc.

If it doesnít run or turnover, thenÖ.it's a different chapter and the ending may not be so happy.

Iím not the most mechanically inclined, nor do I have an ideal work area and Iíll need to order some patience from Amazon. I see this is going to be an ongoing journey but this is a nice bike. I have owned 6-8 bikes in my years; Hondas, Yamahas, KTM, a Goldwing, etc, all many years ago and this is a great chance to get back into riding with a fine machine.

This is another topic for another day, and IĎm sure there is a thread already, but if this bike sorts well, Iím tempted to convert this to a naked K75. Iím 6í2Ē and 260 lbs and feel a little cramped sitting on this K bike. I sold the 97 Goldwing because I was tired of the car dash and lack of feeling from the road. And now I have a history of neck and hip problems.

Is our initial approach and sequence reasonable? What am I leaving out? I want to do minimal to confirm it is a keeper before we get into the other systems. What are things to watch for (here now and later)? All comments welcome.

Thanks in advance!

Brad Fricks
Marietta, GA
1992 BMW K75RT


 
  • Marietta, GA
  • 1992 K75RT

Offline Georgia_Rider

  • Curious
  • Posts: 3
Re: 1992 K75RT Refresh/recommissioning, Near Atlanta GA
« Reply #1 on: January 02, 2019, 11:16:41 PM »
Thanks Johnny, any comments on the sequence we are planning to do this work?
  • Marietta, GA
  • 1992 K75RT

Online The Mighty Gryphon

  • ^ Quintessential Motobricker
  • Posts: 4111
Re: 1992 K75RT Refresh/recommissioning, Near Atlanta GA
« Reply #2 on: January 03, 2019, 12:50:20 AM »
Welcome!  Let's see if we can do this on the cheap and still get it right.  I guess the first thing to do would be to assess some of the more expensive stuff before going into the engine.  Pull the final drive and check the splines on it and the drive shaft.  If they are good, lube them with a good Molybdenum Paste like Honda 77 moly.  The next thing would be to get a quart of DOT 4 brake fluid and flush the system.  I would hold off on replacing the brake lines until I knew if the ABS system is good or needs to be stripped. 

Judging by how long it sat I would expect the rear master cylinder to be corroded and needs to be replaced.  A new one from BMW is beyond stupid in price.  There are threads here on replacing it with an $11 Chinese master cylinder.

Another area that suffers from storage is the fuel system.  There is a good chance of pinholes in the lower spots in the tank.  They can be sealed with epoxy.  You should plan on replacing all the fuel lines including those inside the tank.  Replace the fuel filter(NAPA Gold 3032) when you do the pump and fuel sender.

The injectors are probably stuck from gummed up fuel.  You can send them out for cleaning or look up some DIY videos on You Tube. 

With the tank off, get a can of Deoxit contact cleaner and go methodically through every electrical connection with a little spray and a few connect/disconnects to clean the contacts.  Be especially sure to do the ground connections on the frame backbone under the tank and on the side of the transmission above the shifter.  This would also be a very good time to remove the starter to check the brushes and clean the commutator.  This is critical because several electrical circuits are grounded through the commutator and a poor connection will cause many strange problems.

Pull the spark plugs and shoot a little oil(about a teaspoon) in each cylinder.  Hook up a jumper battery and see if the engine turns over with the plugs out.  Protect the coils by screwing the plugs in just a turn or two and connecting the plug wires.  You may have a problem with the starter or sprag clutch that will need attention.  Run a compression test.  Pressure should be at least 135psi.  I wouldn't be surprised if some rings are stuck.  The oil will help loosen them.  If they're really bad, try some Marvel Mystery Oil.  A teaspoon or two in the cylinder and crank it over a few times and let it sit.

Remove the valve cover and check valve clearances.  At 65K miles you might have exhaust valves that are beginning to get tight.  Record the clearances and the shim thickness.  If any need to be replaced, hold off until you know the rest of the bike is good. 

If everything looks good so far, splurge on a gallon of Shelll Rotella heavy duty 15W 40 at Walmart and a PF53 or equivalent oil filter.  Avoid Fram filters.  They're famous for low quality.  I like the Carquest units.  When you drain the oil, check for water, it may indicate that your water/oil pump needs service. 

Drain the cooling system and check for oil in the coolant.  I would get a gallon of distilled water and a cooling system flushing agent along with a gallon of 50/50 Peak Long Life Antifreeze.  Flush the system with the distilled water and flush saving about a pint of the distilled water to dilute the Peak antifreeze to a 60/40 mix.  Inspect the coolant hoses.  They seem to last forever, so unless they actually leak, I wouldn't bother replacing them.

There is a short hose that connects the engine block to the airbox.  It's referred to as the z-hose and can be found between the airbox and the relay box.  These hoses are usually cracked at the clamps and the resulting vacuum leak causes very rough running.  It's probably the best $10 you will spend on this bike at the dealer.

Now for the scary part.  Put new NGK plugs in, reinstall the injectors with new o-rings, connect the fuel lines and see if you can start the engine.  If you've done everything above, chances are good it will start.  If not, or it starts and runs poorly, we can help. 

Once it's running, you can do the valve shims if necessary and balance the throttle bodies.  Let it run until it reaches operating temperature(about 15 minutes) and drain the flushing stuff and refill with a 60/40 mix of antifreeze.

With any luck, you'll have a running bike and not be out more than about $250.  Then you can start planning the rest of the restoration.
  • In my garage in Marilla, NY
  • '94 K75RT Mystic Red, '92K100RS White, '94 K75S Dakar Yellow
Current:
'94 K75RT "Ilsa, She Wolf of the SS"
'94 K75S "Cheetos"
'91 K100RS "Moby Brick Too

Offline caveman

  • ^ Motobrick Curious
  • Posts: 67
Re: 1992 K75RT Refresh/recommissioning, Near Atlanta GA
« Reply #3 on: January 03, 2019, 06:17:16 AM »
+1 on TMG's post

The only thing I would add is get a service manual, hard copy is nice but at lest down load one off the net. Also since it was last ran in 2013 it most likely has ethanol in fuel so I would pull the injectors out and clean them and the fuel rail and tank (replace all fuel lines!) before attempting to start.

Also I would not get to worked up if compression is low (90 or above) on an engine that has sat this long.

Good luck and keep us posted on progress.
  • Kennerdell, PA.
  • 87 K100RT, 88 K100LT

Offline natalena

  • ^ Proficient Motobricker
  • Posts: 161
Re: 1992 K75RT Refresh/recommissioning, Near Atlanta GA
« Reply #4 on: January 03, 2019, 12:23:41 PM »
+ on TMG and Caveman. Youtube is handy, but a service book is the Holy Gospel.

I can't believe nobody's encouraged the use of Techron, it's like a "gateway fluid" for bricksters. A can in the tank with fresh fuel (muni airports often sell non-ethanol), a pair of black Reeboks, and you'll be on your way to riding Heaven faster than you can say "pass the deoxit."

Good luck, this is a prime place for diagnosis and how-to, except for concerns in cutting the rear loop.
  • East of Joshua Tree
  • 1987 K75s #0919

Online The Mighty Gryphon

  • ^ Quintessential Motobricker
  • Posts: 4111
Re: 1992 K75RT Refresh/recommissioning, Near Atlanta GA
« Reply #5 on: January 03, 2019, 12:44:51 PM »
I didn't mention a manual because I assumed(yeah, I know) that no one would attempt working on a brick without one.  Techron is good, but I only use it in an engine that is running.  It seems to work better for me when it is being circulated by the fuel pump through functioning injectors.  For cleaning injectors off the engine, there are spray can products that are more appropriate.  The goal in my post was to insure that the injectors would flow fuel to allow the engine to start.

While the manuals are critical for getting the job done, the many YouTube videos out there can make a lot of jobs easier to comprehend.

The goal in my post was to get through to a running engine with a minimum outlay of cash, and to identify any major faults before investing too much in the bike.  I hope I was successful.  With any luck this bike will be successfully recommissioned at a cost that won't exceed it's market value, and if not, can be parted out to recoup any expenses.
  • In my garage in Marilla, NY
  • '94 K75RT Mystic Red, '92K100RS White, '94 K75S Dakar Yellow
Current:
'94 K75RT "Ilsa, She Wolf of the SS"
'94 K75S "Cheetos"
'91 K100RS "Moby Brick Too

Offline stokester

  • ^ Proficient Motobricker
  • Posts: 428
Re: 1992 K75RT Refresh/recommissioning, Near Atlanta GA
« Reply #6 on: January 03, 2019, 07:31:34 PM »
All great advice and suggestions.

I would add that Bill Johnson, AKA Mr. Injector, will clean your injectors and provide a flow report for a great price and quick turnaround.
  • Yorktown, Virginia
  • '94 K75S - '93 K75S - '91 R100RT - '78 R100S

Offline Georgia_Rider

  • Curious
  • Posts: 3
Re: 1992 K75RT Refresh/recommissioning, Near Atlanta GA
« Reply #7 on: January 03, 2019, 11:18:28 PM »
Appreciate all the helpful comments! Let the fun begin!

 
  • Marietta, GA
  • 1992 K75RT

Offline DavidATL

  • ^ Proficient Motobricker
  • Posts: 113
Re: 1992 K75RT Refresh/recommissioning, Near Atlanta GA
« Reply #8 on: January 08, 2019, 09:06:15 PM »
PM sent to OP. Tagging the thread to help it get read soon!
  • Atlanta
  • K75RT '92 w/ 24k miles (former bikes: '82 FT500, 80's GL500 Silverwing, 550 Nighthawk and FINALLY an '88 K75S) https://georgiaroads.wordpress.com including my #GA4corners route

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