Master Issue

This weekend, found a pool of brake fluid dripping down the side of the bike, and discovered it was coming from the back of the master cylinder. I pulled the assembly and found some rusting on the outside of the plunger, and decided to pull it apart to inpect.

The inards did not look too bad, pull all the parts, plunger, spring, rubber gaskets, etc. I pulled the top resivour off, and unscrewd the brake switch.

There was some rust on the inside, so I soaked in 100% vinegar for two hours. This cleaned it up nice, and I soaked with thin oil to keep it from rusting again.

Cleaned up all the parts and re-assembled, re-installed, and bam no brake pressure. I will buy a rebuild kit as air seems to be seeping through at this point.

Here is the rebuild kit, $69.00

Picture of ORIGINAL internal plunger for reference

Starting to color her up

Will publish finished bike, plan on doing fenders and then tank, with new BMW emblems to replace torn ones. Should look half decent, I will put clear coat on as best as I can, no pin strips for now.

Rustroleum Black Enamel, easy to find and half decent for a Rat Bike.

New Fuel Line

I have had 3 feet of braided fuel line and fuel filters for a while, the older fuel line and the original fuel filters I installed early in the summer will be kept for emergencies, but for now, new line and filters.

Rear Wheel Cleaning and Lube

Decided to clean the rim on the rear wheel with Mothers aluminum cleaner, and check out the rear brake wear and spline condition. As expected, looks like the lube is hard and dried out.

Give me a BRAKE

Today's plan, clean the rim on the front wheel. Well it always starts simple they say. Got a piece of 2x12 from a building site in the "hood" and propped the bike up on center side, this lifts it an additional inch or so off the ground, I find much easier to get front tire off.

Proceeded to pull front tire off, was just about to place a shim between the brake pads and I noticed how slim the pad looked. I placed the wheel to the side and took the brakes off for an inspection, OH BOY, the outer pad is almost down to the metal and the piston and dust ring have a crusty layer of grease and brake dust.



Now remember this bike came to be with an unknown history, so I'm glad I stopped to inspect. Part of the 10K service is to inspect the brake for wear, so this was on my list anyway for the summer, this and all the bearings.



I went ahead and pulled the caliper off, let the brake fluid drain, and decided to pull the piston to see if it was pitted and dirty, to my surprise the piston looks great, the inside of the caliper was pretty clean, I felt no grit around the o-ring when I pulled it out.

I cleaned up the caliper, removed brake dust, grease, and cleaned the inside well. I will set this aside until new brake pads and dust cover can be ordered. For now the bike will remain in the garage. I will get to cleaning that wheel at some point, but maybe it would be better to do the bearings while it is off.

Valves and Center Stud

After reading more on setting the valves, I decided to redo them. I did not take up the vertical slack on the rocker arms the first time, and each rocker arm had slack. I also reviewed the Owners manual which recommends setting the valves:

• Intake .15mm
• Exhaust .20mm
  

The BMW MOA July ON magazine Keep them Flying article had a article just on setting valves on airheads, and they do recommend the same valve settings.

I had .10/.20, and had vertical slack, so I felt it was worth redoing them.

I also installed the center stud on the right side head which had come loose. The threads seem ok, but I used blue loctite on the stud, I will hand tighten after 24 hours.

A good Sunday

As Ron knows I do not give up easily on these BMW bikes. I decided this morning, to go back under Paul's suggestion and take a second look at the timing under full advance.

I pulled the front cover off (after disconnecting the battery), and decided to lube the advance unit, and clean it up. I then went for a 10 mile ride, at this point came back and did realize that under full advance my timing was around 2800 rpm. I rotated the base plate, and got the advance to hit 3000-3100 at full advance. After doing this idle was a bit low, I carefully adjusted the idle stop screws, and put the gauge on the vacuum ports. It is now running at 1K dead on, after full warm up.

I put the bike back together, and went for another ride, WOW, my power is back, takes off like a banshee, not stumbling, no pinging. My needle jets are set to position three. I got the Bing book, and will check jet and needle sizes during next carb sync, but for now, the bike is running good. When I got back I adjusted the throttle cable just a smidgen, under the gauge, and went for a five mile ride, the bike got even smoother.

At this point with old cables, and carbs that probably need work, I think my R75 is tuned as good as I can get it without more help. She is running good, I will see what kind of gas mileage I get under this setup.

I started to sand and prep the side covers I received from Ebay. I will have to get me some bungys My stock air filter is on order along with the missing valve cover stud/special nut.