BMW R75/5 Restoration (1)

Driving home and a first assessment

During the test ride it drove OK, showing the typical local bike symptoms, the front brake handle could be pulled straight to the throttle lever without much breaking effect, the carbs were grossly out of sync, accelerating did not work because of a replaced throttle assembly and a screwed up gas cable, the engine did not rev well, but it seemed to have lots of torque at idle speed and the frame and gearbox seemed OK. Because someone had fitted custom shocks the back suspension was awfully stiff and each speed bump sent shock waves straight to my backbones.

When driving the cow back to Los Banos the first signs of serious engine damage became apparent. There was the occasional “clunk” sound from the engine, indicating a broken crankshaft bearing. At higher revs the engine lost power and was misfiring, and the valves made a hell of a noise once the engine got hot. Not so good. Anyway, I had a plan to overhaul the engine, so no big problem – I thought.

Before my home leave I took half day off work to dismantle the bike and identify broken parts, after all I was going to Germany where there are still lots of spare parts for the old cows. I already checked my previous contacts for spare parts from theBMW R25 restoration job, and found out that in the meantime even more small companies in Germany have specialized on providing spare parts and even re-engineered components for the old 2-valve BMWs at reasonable prices. 

But then, taking the bike apart was a bit shocking, I should have expected it because it always happens when I get involved with a newly purchased bike in the Philippines. As usual countless local mechanics had tinkered with the bike and made most serious modifications:

Engine and gearbox

  • The centrifugal timing advance was welded onto the camshaft. The engine could not be taken apart without further destroying the device and the camshaft
  • Crankshaft bearings and connecting rods bearings were worn
  • Exhaust threads are worn completely (which is sort of normal for a bike of this age)
  • Kick starter hung when operated and had to be pushed back manually
  • Main crankshaft seal leaked into the clutch compartment
  • Gearbox leaked at several places

Frame and suspension

  • Some metal triangles were welded to the frame to serve as seat holders for the third party single seat
  • The rear shock absorber bottom point was moved backwards. Probably because it is supposed to look cooler than a shock that runs straight down.
  • The battery holder was missing, instead the battery was placed loosely on a fiberglass fitting. One of the acid replacement openings was open, frame parts were corroded from leaking acid.
  • The wheel bearings were replaced, all fittings to adjust the bearings were taken out.The back wheel was ruined.
  • The swing arm bearings were also not original. The swing arm was very stiff.

Others

  • Rear Handle and throttle mechanism was replaced and did not work properly, in fact did not work at all.
  • Switches in head light and at handle broken or missing and replaced with automotive switches
  • No air filter installed
  • No choke mechanism
  • The electrical system was completely screwed, no part original. Two diodes in the diode plate were burned, blinkers did not work, a complete mess.

I started realizing that there was  lot of work ahead of me.