2009 Sumamry - 1976 R75/6

June-July 2009 / Mileage 65, 945 (10K Service)

Spark Plugs replaced (Boxers by Bruce)
Fork Oil Replaces (Boxers by Bruce)
Air Filter Replaced
Brake Fluid Replaced
Transmission Oil Replaced
Final Drive Oil Replaced
Drive Shaft Oil Replaced
Inline Fuel Filters
Lubed Swing arm
Engine Oil/Oil Filter/Oil Pan Gasket/Cleaned Screen and Pan
Adjusted Timing
Checked Valves
Sync Idle and Full Advance
Lubed Advance Mechanism
New Brake Pads, Caliper Dust Cover, Reused Oring-New Fluid
-------------------------------------------------
Oct 2009

New Braided Fuel Line/Filters

Installed new rubber seal around ignition/points area

Nov 2009

Cleaned Exhaust Fin Nuts (New Wrench)

Spline Lube being performed

Dec 2009

Swing arm repacked and put back on bike

Master Cylinder Rebuild Kit seems to fix MC issue, bought a MightyVac to assist in bleeding brakes, and redid E-pin.

Ride and Sync

I put the rear fender back on, and lights, rewired the brake and turn signals. I decided at 50 degrees I would go for a ride and see how the bike handles after spline lube, and swing arm bearings, etc.

The bike shifts very easy now, and tracks well. The older shocks I put on seem a bit more spongy but ridable.

When the weather turns nice again, I have decided to give the front fender, rear fender and tank another coat of paint. The Black Rustoleam is protective, but I'm thinking of putting a lacquer coat of Dupli-color on the "tins" to make a nicer look, gloss black.

I have not put the new BMW emblems back on yet since I'm not done painting. The bike looks rough, but runs nice.

After the ride I used the carbtune on the bike, to see where the new throttle cables were at. At idle adjusted the screws so they were even, right around 800-1000 rpms.

I also tried to sync the throttle cables at higher RPM, did the best I could do alone, it is very hard to do this quickly alone, need a helper next time to get it right.

Mighty Vac

Today after failed attempts to get the front brake bleed correctly, I broke down and bought a Mighty Vac. Since I will attempt to bleed the brakes in my RS after the winter I thought this would be a good investment, $39.99 at O Reily's.

After hooking it up I followed the instructions to bleed the brakes. The handling is better, but not quite there yet. I pulled the caliper off to tap any loose bubbles that might be in the piston area. I put everything back together with only slightly better results. I will try again after winter break. Not sure the bike is ready to ride, it stops, but probably not like it should.

Spline Lube

Gearing up for a spline lube, since the rear frame member is off.

Steps I performed, I knew I was going to remove the transmission

Remove Rear Frame/Seat

Remove Airbox/Tubes

Remove Battery/Battery Box

Remove Swingarm with Wheel/shocks connected (disconnect final drive from tranny)

Remove Clutch Release Mechanism

Remove Transmission

Clean up splines, relube

Clean up Clutch Release and re-grease

I had to order a new clutch throwout bearing, this little item set me back $28.00

After the splines were all put back together, I packed fresh grease in the swingarm bearings area, and put the rear section back together. The swing arm is no to difficult to align up centered. I use some wooden skewers that were just the right size as spacers as I tightened everything back up.

Fins to the Left, Fins to the Right

Took my new exhaust fin wrench out to the garage and tried it out on the left and right nuts. After spraying some deep creep into the groves, the nuts came right off, fresh antisieze paste looked like it had been applied recently.

Buffing up the rear

ith the tank off, and master cylinder getting repaired, I thought it might be a good idea to good ahead and paint the rear frame member, I have been lightly sanding areas where rust has been starting to show up.

I removed the seat, unbolted everything, and put pull strings through the rear frame tubes for the brake lighting.

It might be a good idea to go ahead and do a spline lube with everything off the rear, that will entail removing the swing arm, etc, which I do not have the right tools to do right now.

Rear Brake Lighting, just in case I forget

New Throttle Cables

Need to sync carbs, now that new throttle cables are on.

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.

State of condition

In summary

• I modified carbs, good idle, but poor acceleration (Tech Day at Pauls)
• I modified timing, good idle, still poor acceleration (was on OT, now on S with line above)
• I modified needle position from 2 to 3, good idle, poor acceleration, and pinging at higher rpm's, speed, loss of power
• Check valves, re-adjusted head bolts to 35nm, but valves read .10 and .20, so no modification.
  

Next Steps
Stock Air Filter
Re-Check timing (operating temperature)
Install new stud bolt and nut/washer

Advance Unit

After reading about the advance unit more online, I thought it would not hurt to check the lubrication of the advance unit. After what Paul told me in an email about re-check timing, I noticed that the advance unit was full advance around 2900-3000 rpm, and it should be around 3000-3200 rpms. This could be causing the pinging.

Check the valves

Today I wanted to verify the valves. It is warm outside but the bike has been sitting for a day, and the temp on the heads reads 88 so we should be ok.

Proceeded to to loosen and re-tighten the cylinder head nuts to 35nm of torque, and checked both left and right valves. Believe it or not they were all spot on, intake .10mm and .20mm for the exhaust. I was really surprised to see both side dead on.

Now I will change the air filter and proceed to re-sync the carbs.

Pins and Needles

Today after thinking more about the carb issue, I decided to check the position of the carb needles. Now the bing book according to Paul suggest setting the needles at position three which is clicking the needle all the way up the diaphragm tube.

I removed the carb tops but left the cable sin tact, diaphragms look ok at a macro level. The needle positions were the same, but they were set to position two in the middle. Given this bike has a K&N filter someone might have set these to "rich", I think.

Anyway I went ahead and put the needles back to position three, and we will see how the bike runs for awhile in that position, will check plugs in a couple of weeks for color, etc.

It is all in the Timing

After yesterday's carb sync, I realized I should have checked the basics first before doing the final tuning procedure, doing it backwards in my mind only creates undo frustration. I decided today that I would check the timing of the ignition to make sure we were not fighting a timing issue. I proceeded to check timing after a short garage warm up.

The timing mark OT was appearing in the window during idle which indicates it is not in timing. The S mark with the line above it needed to appear in the window for dead on timing. I loosened the base plate of the electronic ignition, and adjusted it back and forth until I got the line to appear right at the middle mark in the timing window.

After I test ride I re checked the setting, and it remained right on mark. The hesitation did not go away but the bike did seem to run a bit better on a 10 mike test ride. The idle is still a little high at stops, around 1100, needs to be adjusted,

Carb Sync

Today, Ron, Paul, Doug and myself got together for a kinda of a half day Tech Day at Paul's House. I rode my Bike with some breakfast, Doug brought fresh coffee and Ron brought beer which never broke into.

Upon arrival I noticed some brake fluid seeping down the left alternator cover. So before we dove into cars, I pulled the tank to discover the cable connection to the master cylinder has vibrated loose and was dripping every time I squeezed the lever. Paul was gracious to offer DOT3 brake fluid, and Doug and I proceed to tighten the suspect cable, and bleed the brakes given the lose of fluid. After a quick road test front brake working great. I ntoiced now the front wheel is dragging a bit, so the caliper will most likely need looking at.

After this we discovered some loose wiring under the tank and the left coil plug wire was loose. We cleaned and put dielectric grease on most of the wire connections, zipped tied the loose cabling up, and generally inspected all items under the tank.

We proceed to look into the carbs.
Paul demonstrated the shorting method, of plugging spark plug adapters into the top of each spark plug them attached to the coil wires. While bike running, you short each cylinder to see which is one is pulling to indicate where the adjustments needed to be made. This was great learning from me, because I had never seen this done correctly.

Paul's order of operation was to loosen the throttle cables and set idle first by adjusting the idle stop screws first to reach correct idle speed, then he proceed to adjust idle mixture screws one by one u until it was set just after each cylinder would die out. He did all this by ear and watching the RPM's. We got idel running pretty smooth.

After doing this by ear we stuck Paul's carb stick on to make final adjustments. The bike was idling very smooth but we detected a new problem. Right off idle the machine coughs and acts as if it is going to stall, almost like the idle mixture is too lean. Paul suggested it might bu need position of carbs needing a good overhaul. Even though we created a new problem with suspect carbs, the sync procedure was a good learning experience, and I will not hestiate to try this by ear first.

New Rubber

Today I received my original BMW owners manual, a blank key, and the new rubber sleeves for the carb to head, and carb to airbox tube connection. The old rubber sleeves were hard and cracked and might have been leaking, before a good carb sync I thought I would swap them out, can not hurt. The new ones went on with out a hitch.

Thanks Hans from Hucky's for getting the parts to me so quickly.

Oil Change, Filter, and Pan

Today I wanted to finish off the fluids in the 10K service, I waited to do the oil filter, and engine oil until I could order a new oil pan gasket. Went to Hucky's and got me a oil pan gasket. I proceeded to drain oil, change filter, dropped oil pan, much black sludge but no real metal in the screen or pan, just thick older oil. I cleaned thoroughly. The older oil pan gasket came right off without any fuss.

The oil filter cover had at least two old paper gasket cover which I managed to clean off the cover and engine case 99% without any damage to each. I changed the filter, screwed in the main bolt and cover, and put a fresh gasket on. The oil filter bolts were replaced at one point with good hex bolts and washers.

The oil pan and screen were cleaned, and reinstalled with new oil pan filter, hand tighten the bolts down lightly, and put a fresh crush washer on the oil drain pan bolt, 30NM torque.

Filled with 2 liters of Castrol Act-Evo 4T, and topped off with my left over Spectro Golden 4, both 20W-50 weight.

I did reuse the oil pan bolts and washers, will watch for leaks, and possibly order new washers for the 14 bolts.

Pictures

Progress

At this point I wanted to re-assemble the bike to working order in order to get the Texas State Inspection completed, so I can register and tag the bike for riding.

I had removed the rear fender, taillight assembly to get to the battery tray easier.

• I started to clean the swing arm on the left side
• Misc sections of the frame were sanded
• Cleaned out the oil in the points area
• Started 10K fluid changes
• Put Points cover, start cover, and air box back together
• Put Rear fender and tail light back on
• Battery re-connected with battery tender plug back on
• Greased Swing arm

To Do

• Change Oil/Oil pan gasket
• Finish 10K service, Valves, Timing, Cable Lube, Sync Carbs
• Centerstand needs to be restored
  

Finishing up Battery Tray

The battery tray was re-installed today, and following the Airheads.org club canon #2, "Airheads believe that the simplest engineering solutions are the best." With this in mind I looked for the rubber vibration bobbins that connect the battery tray to the frame. These little dampeners cost $13-18 dollars a piece x 5 from BMW, so to spend $65 seemed a bit high, so I went forward with my solution.



Went to Ace Hardware and bought 5 rubber stoppers @ 43 cents a piece, cut them down to the dampener length, drilled a 1/4 hole through the center and proceeded to bolt them to the tray and frame using M6 metric bolts, washers and nuts. Overall the cost was less than $5 dollars, looks good, and holds the tray solid.



The original dampeners are rated to hold 25lbs a piece, and the rubber stoppers are rated around 22 lbs so this seems sound, proof is a year from now.

A Stiff Drink

Today after discovering that no fluids had been done by the former mechanic other than fork oil, I decided to start into the 10K service for the bike.

NOTE - BIKE IS APART DOING BATTERY TRAY SO FLUID CHANGE DONE COLD ENGINE, NOT THE BEST BUT STILL BETTER THAN NOT DOING.

I have Golden Spectro Gear Oil which is what is bottled for BMW.

Amounts

• Transmission - 800cc
• Final Drive 250cc
• Drive Shaft 100cc

Inspection

• The Transmission oil was water contaminated, brown, stunk and had traces of milky white fluid.
• The Final Drive oil was also water contaminated, but not as bad
• The Drive Shaft oil actually looked fairly new

I went ahead and bleed the brake fluid which looked a bit dark, and replaced with DOT3 brake fluid, worked out the big bubbles, and will let sit over night and check again.

Some cleanup

Here are some pictures of the electronics, there is a gummy oil leak on the left hand side of the alternator wiring, might be a cam oil seal leak, goign to dig in

Battery Tray

Decided to start on one of the simple items, the battery tray. Like other older airheads this tray is usually rusted at the bottom, acid damage, and the rubber mounts are broken, rusted, or damaged. Mine was all of the above. These trays are over $150 to replace, so care and feeding is necessary. A can of black gloss rustoleum does wonders, after a good sanding.

Once I removed the battery, big heavy Panasonic, does it really need to be this big?

I discovered that to really get the tray out, I need to remove the rear fender, so I started to unbolt the rear fender, well that leads to removing the rear taillight section which is all in all very time consuming. It did allow me to inspect the inside of the rear fender, and clean out underneath. Close examination, I think this fender has been repainted at least once. There are tape lines around the tire information sticker on the top of the fender.

I worked on removing the rusty nuts and rubber vibration dampening mounts, some might be ok, but at least three were damaged beyond use.

Looking online at the BMW parts fiche, they want over $15 a pop, and you need five of them with washers and nuts on both ends.


Hucky's has them for $12.00, but that still seems high.


I searched the Airheads.org archive email list and found a post, Tom Cutter responded two with two sources for replacement parts.

McMaster Carr has these for $6.00 a pop, need to check size, but will save some money.

http://www.mcmaster.com/#4403k722/=28tuoa

From 1976 BMW R75/6

Seafoam Treatment

The first thing I did is to run about 4 oz of seafoam through each carb to blow out the crud. The bike idles pretty good, vibraton felt at the top end on the rpm's, will have to sync at some point.

Another Horse in the stable

Today I bought a 1976 BMW R75/6 from Boxer's by Bruce, a local Beemer mechanic in Arlington, Texas. Bruce had this bike on Craiglist as a consignment. She is not the prettiest, but seems to run good, and no oil leaks, YET.

The compression test show around 125 PSI on both cylinders, not great, but better than 123.

VIN 4945953
Mileage 65,894 (odometer migh tbe broken)

BMW 1976 R75/6 Airhead

From 1976 BMW R75/6