The (leaking) brick - a perfectly adequate motorcycle (part 4)

In the last installment "Geraet" passed it's inspection, got registered and I took for the first few smaller shakedown runs. Whilst being "legal enough" to take part in traffic, the old girl was pretty good from afar, but far from good. 

First on the list were the brakes. The pads were at least twenty years old and definitely had seem some oil or other lubricant at some point and whilst proper steel braided brake hose improved the overall brake performance quite a bit yet those calipers were definitely dragging. 

The blue Brembo pads, even though being the "budget" organic version already made a huge improvement.

Next task: have a spare key made. I only had one original key and that was the folding one, which felt distinctly wobbly in the joint and I was quite afraid of breaking it off. 

Both gearbox and final drive oil were also definitely well overdue for a change, yet revealed no sparkly surprises.

As oil had been sitting forever in both the gearbox and final drive, I gave them a good wash with some diesel. 

 And then admittedly after two or three rather spirited test-rides the engine started to look like this.

And a bit more coolant and less oil on the other side.  

In other words: waterpump-seal-time.

Now THIS is officially a lot of dirt and oil on top of the waterpump.

After a moderate amount of cleaning.

Doing the seal swap requires one special tool and I personally would highly recommend you buy it at the shop you buy your seals too as the stock seal is only about 9mm tall and the (improved) aftermarket one, over 11mm. Which means, I had to alter the seal-driver to take those extra 2mm into account. 

The pump shaft only needed a quick cleanup with a piece of scotchbrite to be all shiny again. The pitting is well within the coolant section and not where the seal runs.

Checking the height of the new seal.

 

So there's an official tool from BMW to drive the seal in, called the "BMW coolant seal installation mandrel", which has the following dimensions:
Outer diameter 40mm
Step diameter 28mm
Center-hole 12mm
Step depth 8mm - which I therefore changed to 10.5mm

Even though it may seem counter-intuitive, there should be about a 2mm gap, so when tightening the waterpump rotor bolt to spec, there is the correct pre-load on the seal. 

 

Installing and aligning the pump, especially as there's an o-ring on the back, is a bit tricky, but nothing out of the ordinary, just expect to have liquid gasket on your hands everywhere. 

As there's literally no way of ever cleaning the gunk out from on top of the water pump, I decided to trim it to size quite notably so riding in the rain would effectively wash the road dirt off. 

 ... and only a few days later, I completed the first 1000km on the beemer. 

 At the time of writing it's almost a thousand more and whilst it is still not what I would call an exciting motorcycle, I'll admit that it is undoubtedly a very useful one. So useful that I'll soon have to replace the rear tire for the first time.  

The (flying) brick - a perfectly adequate motorcycle (part 3)

There is a distinct difference between running and R-U-N-N-I-NG. (And also all the variants of the same general topic in between.) As a matter of fact, the BMW was running, but for example it wasn't idleing and it wasn't overly happy to rev up as well. 

So step one was to sync the carbs - this was the starting point, where I had only done it by ear, which I have to say... not too bad. 

 If I held the throttle open far enough, it would run perfectly at around 1100-1200rpm. 

 Which then made me think, even though all the manuals (and the forum) warn against altering any of the mechanical settings, the way the throttle stop is adjusted looked dramatically different to what it is set to on other K75s. So after a bit of tweaking, I simply set it, so it would hold a nice and steady idle at around 1000 to 1100 rpm, when warm and about 850-900rpm, when cold. 

Strictly speaking none of this should ever be necessary on a well maintained bike 

The throttle position switch was completely maladjusted before, as it was almost perfect once I had set the throttle stop so it would idle, indicating that I might be on the right track.

The ignition baseplate is generally meant to be left alone. Clocking it, so it  was set up in the base setting made the engine run much nicer almost instantly. 

 The other challenge was that the overall performance was rather... moderate. As the throttle is geard, it can be set in various positions. Not all of them allowing full throttle.

The result of all those efforts was quite staggering compared to the clip at the top of this post. 

 Bit of tidying up here and there and passing the inspection was actually a breeze.

 As the first ride after getting the bike registered already turned into a wet (and thus cold) one...

I attempted to fit a pair of R100GS handguards. Attempted, because aside from various claims that they are a bolt-on thing, they needed quite a bit of modification to actually do.

The BMW definitely didn't improve its looks, but as I can attest after the first (slightly) longer rideout, it keeps my hands warm and dry. 

 Lastly, given it's somewhat practical nature, yet it not sparking overboarding enthusiasm, I found a name for it: Geraet, which means device or as it is meant in this case, appliance.

The (walking) brick - a perfectly adequate motorcycle (part 2)

So the last post left off with a lot of carnage caused by the fire in the airbox and a lot of broken rubber bits. Let's start this one off with a lot of broken bolts. Starting with a small dab of weld and then progressively larger nuts...

Four out of six bolts that held on the inlet rubbers broke off. 

 

Coolant didn't look too bad, considering it is most likely more than 24 years old. 

 The fan on the other hand has lost a blade over the years. 

 In order to remove it, I had to slightly modify a two-arm puller get the old fan blades off the shaft. 

Apparently at least at some point in the past the motor shaft had come loose and touched the radiator.

Re-assembly was substantially more simple - just press the fan back on and reinstall everything with new hardware. 

While I was at it, a new thermal switch was also installed into the water neck as it would be almost impossible to get to later with the radiator installed.

And because I had to have everything out anyway, I also installed a new fuel pressure regulator. 

Reassemble everything and bleed the cooling system, which to the engineers' credit goes a lot easier than on many cars that I've worked on. It is literally, fill in some coolant, check for leaks, wait for the bubbles and fill some more. When you're done, fill the overflow tank.

Next step necessary to pass inspection: New(-ish) tyres. At least ones, which are too young to vote. 😁 (Front tyre was from the 3rd week of 1992 according to the markings on the sidewall.)
 

The wheels themselves came out without much drama and I have to admit, the mounting on the rear is brilliant. Really easy to get a wheel out. Four wheel bolts and that's it. 

 

 The front on the other side: Started off with two bolts seized in their holes in the forks...

... and this one bolt hidden behind a cover on the back of a fork brace.

Surprisingly (again), the bolts for the fork brace came out with a lot of heat, but could be used again.

It is important to note that those mudguard mounts are not threaded, just packed full of dirt and corrosion. Both from the bolt AND the actual fork leg.

Why all of this? To be honest, just to fit those fork gaiters and be able to reinstall the forks properly again.

 

While the rear wheel came out without much of a fight, the rear drum brake left a lot to be desired. First I marked the lever position on the shaft. 

Then covered the whole shaft in plenty of oil to soften up the caked on remnants of grease and brake dust.

Re-Assembly of the drumbrake is really easy, if you remove the C-clip on the top and just slide everything in place. (No special tools needed.) Don't forget to lube the shaft where it passes through the housing and check the two o-rings, so grease can get into the drum. 

Even after doing the brake fluid (and then bleeding them again) didn't help much, I had a closer look at those brake lines and sure enough... 08/1986. 

 

I still had some leftover brakelines from the TR1 and a local hydraulics shop was able to supply me with a long M10x1.0 banjo bolt. Bit of bleeding and... yep, calipers need an overhaul too, but at least now I can feel the stuck pistons.

Then, lastly, rear wheel out again as the seal of the clutch pushrod had started leaking. When I tried to remove it, it completely fell apart. 

 So this point, the limping brick was at least a walking brick and capable of keeping it's fluids inside of itself.