Awakening 1987 K100RS from 10 year slumber.

[SpecialK]

 Took out the rotted fuel pump and innards today. I kinda knew what to expect since the pump has been stewing in bad gas for 10 years so no shocks here. Probably going to order the kit from EME.
The fuel level sensor is toast also so I will either order new (seems the only ones available are BMW OEM) or do without for a while and track my mileage between fill ups.
Will try to get a pic of the tank inside. Looks to be some corosion but it should come out.


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[Laitch]

The fuel level sensor is toast also so I will either order new (seems the only ones available are BMW OEM) or do without for a while and track my mileage between fill ups.

EME also has that part if it's the float type.

[SpecialK]

It's been over a week since the first project post. I got the tank off today after taking advice from another post to take the seat off and stradle the bike and pull up. The fuel level sender wire was unplugged and the rear of the tank free from the two rubber gromets (12mm circlips were still on there so took them off). Even after loosening the hose clamps on the fuel lines they were on the tank nipples very snugly and could not be just pulled up from stradling the bike. I ended up grabbing the left side of the tank with my right hand, where the fuel lines come out, and pulled up using my left hand to grab the rubber lines and wiggle while I pulled up with my right hand. Success!

Yes I have the float type fuel level sensor (see photo). As you can see it is toast and used or after market are hard to find so looks like I will spring the $224 from EME or from MAX BMW same price.


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The tank was about as dirty and full of rotted rubber vibration foam as others I have seen posted.


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I suspended the tank by a wire through the two rings near the front of the tank. I wanted all the crud to fall into the end so I can remove it. I sloshed some gas around in there to wash the particles down and then siphoned the gas off with the siphon tube.


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I also plugged the two fuel lines so as not to get any dirt falling into the lines. I did not have golf tees so I used pens that seemed to work well.


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Here's a shot of the inside after spending about an hour just trying to get the particles out, using gasoline and rags. I scoured this one area with a 3M Scotchbright pad. After the tank dries out I am planning on using the two bottles of white vinegar I saw posted here. Will inform of the results with that.


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[volador]

Phosphoric acid solution or truck wash using a parts cleaning brush or double thick chip brush clean that tank lickety split
Save the vinegar for your fish and chips and salad
Good Day

[Scott_]

We used to have a machine shop here that could steam clean fuel tank internals. An option to consider.

[The Mighty Gryphon]

Phosphoric acid solution or truck wash using a parts cleaning brush or double thick chip brush clean that tank lickety split
Save the vinegar for your fish and chips and salad
Good Day

White vinegar has done the job for many of us, and the price is very attractive.  Especially so, when he already has it.  Granted, it smells funkier than the alternatives, but this time of year you can do the work outdoors.

[natalena]

Although Phosphoric acid works well, using White Vinegar and draining on sawhorses will be eco-friendly since a sprinkle of pelletized lime will get the soil back to neutral pH ... otherwise it'll look like The Big Red Dog took a leak in your yard.

[SpecialK]

I was reading about Phosphoric Acid the ingredient in Naval Jelly. It says it should not be used on aluminum, only ferric metals (steel, iron). Actually rust is the oxidation of ferric metals like steel and iron. So aluminum does not rust, it corrodes or oxidizes creating aluminum oxide. Anyway, I think I'll try the vinegar.

[SpecialK]

Well, I am totally thrilled with the vinegar outcome! Thank you Gryphon for the suggestion. I suppose the grime in the tank is a type of varnish left by the sitting gas and is not as hard to dissolve as it looks. I used (2) one gallon bottles of white vinegar and only let it sit 24 hours. I capped the fuel supply tube with left over rubber fuel hose so the vinegar wouldn't leak out. I cut the float arm and sensor device off the fuel gauge mounting plate and scewed the plate and old gasket back on to seal the bottom of the tank. Today, after the tank sitting for 24 hours in vinegar, I came home and made up a little scrubbing device from a 2' piece of 1/4" dowel with a piece of scotchbright pad attached to the end via one of the hose clamps. With the dowel I didn't have to worry about scratching the tank. I got into most of the nooks and crannys and was able to scub down the sides pretty well. Siphoned off the vinegar and rinsed the tank with the garden hose jet spray (that worked really well). Now the tank is drying out for a final vacuum tomorrow.

Here's the scrubbing device.

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Before and after.

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Two more angles.

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Here is a shot of the damping material on the tank bottom. It looks in good shape so I don't plan on replacing it.

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So it looks like the tank is almost ready to go. I would appreciate any input as to the sequence of list items to tackle before attempting to start the bike. Keep in mind the bike has been sitting for over 10 years with gas and all other fluids in it.
Here is a list of items that I know needs to be attended to but not sure what would be the correct order:

New battery
Check radiator, drain, flush, and new fluid
Check and possibly clean injectors
Replace spark plugs
Air filter
Change oil

Once I get the bike running I will plan on replacing brake fluid and lines, checking calipers and pads, make sure all electrics work, new tires, etc.

Thanks!

[Laitch]

I'd kill off that grass in there, too.

[Scott_]

I'd imagine that the injectors will be fouled up.
The fuel pressure regulator might give you some grief, but it may be fine. You won't know on it till you get the tank back together and run the fuel pump.

[The Mighty Gryphon]

When I see these funky tank interiors I can't help but wonder what the inside of the fuel rail looks like. 

I know that it has taken me several thousand miles and at least five or six bottles of Techron to get my K100's running properly after extended idle time, even after the tank was flushed.  I often wonder if it's crap in the fuel rail getting down into the injectors.

If the engine doesn't run well when you start it, even after running a couple tanks of fuel through it, I might consider sending the injectors and the fuel rail to a good injector cleaner to have them all cleaned out.

[SpecialK]

When I see these funky tank interiors I can't help but wonder what the inside of the fuel rail looks like. 

I know that it has taken me several thousand miles and at least five or six bottles of Techron to get my K100's running properly after extended idle time, even after the tank was flushed.  I often wonder if it's crap in the fuel rail getting down into the injectors.

If the engine doesn't run well when you start it, even after running a couple tanks of fuel through it, I might consider sending the injectors and the fuel rail to a good injector cleaner to have them all cleaned out.

Mr. Injector does it for $17.50 for GDI injectors

[natalena]

It doesn't take much time or expense, but I'd change the tranny fluid and final drive fluid. Checking and lubing the FD spline is a piece of cake, and takes an hour of leisure wrenching. If nothing else, it'll give you peace of mind and a starting point for maintenance.

[volador]

Mr. Injector does it for $17.50 for GDI injectors

Old injectors belong in the Bin.:hehehe Upgrade to the latest and greatest from Bosch and tills.de. A matched EV14 injector set.

Upgrade the OEM fan to a Spal Fan and add  The Johnny blanket.

Tills.de parts order received in 5 days via DHL.

Since you have the tank off and if so inclined, adding a headlight relay if the moto does not have one will improve bulb output and preserve headlight switch assembly.

https://www.motobrick.com/index.php?topic=268.0

http://www.motobrick.com/index.php/topic,4962.msg30932.html

http://culayer.com/product/matchbox-headlight-relay/

http://easternbeaver.com/Main/Wiring_Kits/H4_Kits/h4_kits.html

Eastern Beaver parts received in 5 days via Japan EMS.

Upgrade the battery cabling with the EME Battery Cable Kit (4 Gauge) - BMW K Bike; Neg 61 12 1 244 577

Squirt some penetrating oil or Marvel Mystery Oil into cylinders on the plug change

You'll be ripping up Dutchess in no time

[Laitch]

Here is a shot of the damping material on the tank bottom.

That is insulation—not damping material—to reduce engine heat transfer into the fuel tank. It can be renewed at relatively little cost with material like Reflectix and its effect improved on the RT and RS models by being installed as a johnny blanket.

[SpecialK]

It doesn't take much time or expense, but I'd change the tranny fluid and final drive fluid. Checking and lubing the FD spline is a piece of cake, and takes an hour of leisure wrenching. If nothing else, it'll give you peace of mind and a starting point for maintenance.

Good suggestion, thanks.

[SpecialK]

I'd kill off that grass in there, too.

No, It's necessary for the green fuel movement.  :giggles

[SpecialK]

I drained the radiator yesterday but I couldn't find the drain plug in the water/oil pump (see Haines photo). I got under the bike with a light and for the life of me did not see that plug. Could there have been different style pumps without the plug? I ended up taking the hose off the water pump to drain it.


Haines manual shot of drain plug.

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[rbm]

There could be a temperature sensor installed on your pump in that hole instead of the plug shown in that photo.  That sensor would have been used by the water temperature gauge as part of the auxillary instrument package (if your bike originally had that option).  But all oil-water pumps for the classic K's were the same.  In that photo, you can just catch a glimpse of the rubber boot over the oil pressure switch that goes to the OEM gauge cluster.

[SpecialK]

There could be a temperature sensor installed on your pump in that hole instead of the plug shown in that photo.  That sensor would have been used by the water temperature gauge as part of the auxillary instrument package (if your bike originally had that option).  But all oil-water pumps for the classic K's were the same.  In that photo, you can just catch a glimpse of the rubber boot over the oil pressure switch that goes to the OEM gauge cluster.

Thanks Robert, they said I would get a lot of knowledgeable replies on Motobrick. I did see a rubber boot where the plug should be and there is a sensor in there. I also have a temperature guage on the fairing

[SpecialK]

Checking and lubing the FD spline is a piece of cake, and takes an hour of leisure wrenching. If nothing else, it'll give you peace of mind and a starting point for maintenance.

I would plan on doing this. I have some invoices from work done back in 1991 that shows the spline servicing was done at 7,000 miles and the bike now has about 15,000. Do you think it would still be in good shape after 8,000 miles? Thanks

[natalena]

I would plan on doing this. I have some invoices from work done back in 1991 that shows the spline servicing was done at 7,000 miles and the bike now has about 15,000. Do you think it would still be in good shape after 8,000 miles? Thanks

Not due to mileage, but rather extended time, the spline lube could very well be dried out and the consistency of stale Pop Tart filling. I would guess blueberry. Anyhoo, removing the rear wheel, supporting the drive so it doesn't sag down and ruin the rubber bellow (I just use a jack stand and piece of wood), and removing the 4 hex bolts is one of the easier things to do on the brick. Hint: make sure the wheel spacer is in place when bolting the rim back on. Cheers!
afterthought ... you could check/clean the speedo pick-up on the FD at the same time.

[Laitch]

To followup natalena's observations, changes to improve durability of the splines occurred around 1989–1990. These changes helped extend service intervals out to approximately 40K miles. Your model year indicates annual lubrication for the transmission input splines on the BMW service interval form but I doubt many riders would consider performing the procedure that often.  A machine that has only been ridden a couple of thousand miles might need relubing. A machine that has been mindfully ridden might not show symptoms for tens of thousands of miles. A machine that is ridden hard over rough pavement and gravel might need looking at sooner.

The underlying concern is whether the factory techs actually did the procedure correctly. My inclination would be to lube them now then check again in 10K–20K miles depending upon how many miles are ridden annually, how hard the machine is ridden and how well it is downshifting.

[Laitch]

I think many here lubricate final drive/driveshaft splines at every tire change. That interval would fall somewhere between 5K to 11K miles.