The newest ride, a 1970 BMW R75/5 with my daughter, the day I bought it.
CLICK HERE FOR PHOTOS
The same bike 18 months later, ready for a road trip.
Restoring a 1970 BMW R75/5
This is probably going to be a long and somewhat disorganized page. So it goes.
February 2008: Diagnosis of engine woes.
- Need clutch.Throwout bearing is showing.
- Valves quite worn.
- 50% leakdown on rings.
- Head gasket leak.
- Pushrod seals leak.
- Carbs need cleaning - prob. some grit causing leakage.
- Possible rod knock?
October 2008: Strategic Plan.
- Look for local expertise on /5 bikes.
- Who does machine work on /5?
- What other local resources are there for knowledge, tools etc?
- Who's good for painting? Pinstriping? Powdercoating?
- Inspect rods. Loose bottom end very expensive proposition, also requires full engine removal.
- Also inspect heads, cylinders, to determine what machine work is needed, what parts. Document fully.
- Next, pull and inspect tranny, clutch, splines. Again potentially some expensive issues here.
- Then assess the whole job. If major engine components are OK, don't need to do a full tear-down and can address clutch, valves and some worn-out bits, clean carbs, do a lot of cosmetic/detail items, and get it running again. Do a full-scale road test and probably electronic ignition. Under this option will need to make a list of all parts & tools needed, all services required, find sources, place the orders, and get full documentation on the procedures before doing the work.
- Alternatively, if there are major engine woes, have to consider repair vs. replace, check out options, then decide how to proceed.
Plan for initial work, to get to the point where I know how big the job will be
- Remove exhaust system and carbs - see website info on exhaust nuts - needs a special wrench.
- See "pushrod replacement" at Airheads.org for a good overview of what's involved in pulling heads and cylinders. Also review /5 and Haynes manual, and check websites (Snowbum, Ausherman, Lagiarder, Vech, Cutter) for tips on pulling cylinder heads and cylinders. Find out if any special tools needed. Need reassembly gaskets? Inspect valves. Likely worn. Need to send out; to whom?
- Remove pistons, various measurements to see if boring is needed and if replacement rings are needed. Check rod measurements.
- Then move on to final drive, trans and clutch removal/inspection. Again check manuals and websites first.
- Exhaust nut wrench, trans output flange bolt torque extension, alternator removal bolt, swingarm nut socket. All ordered from Northwoods Airheads.
- How to treat the aluminum cases, to make them pretty again? Try the simplest thing first: Simple Green with brass brushes.
- Snowbum has a nice page on tools. CycleWorks and Northwoods Airheads have good array of specialty tools.
- "Hardware kit" from Hucky's has almost all visible nuts & bolts in stainless steel (not mandatory but if not, I WILL need lots of new fasteners; cheaper in the long run to buy the whole kit).
- seat (and any attachment hardware; optional; 1970 style was smooth leather, not pleated, with grab rails)
- Saddlebags: One rubber mounting grommet is missing. Fore top left bolt (top shock mount bolt) is wrong; need clevis pin bolt and clevis pin. Lower bolts need proper nuts and washers, though the bolts may be original. Top aft bolts are totally mismatched, need to find what they should be and get them. Need to polish saddlebags and put gasket rubber around the tops, and get a key, and maybe some other stuff; not sure what other than gasket rubber this will require.
- Luggage rack: Can't use with new seat. Aft bolts are nylocks; what's original? Doesn't matter if they will be under the seat; will they?
- air pump, tool box and tool kit are missing. Repro tool tray from northwoodsairheads.com. Tool tray edging, tool kit, air pump all available from Hucky's.
- Handlebars scored with flaking chrome; replace with new low Europe style. Hucky's.
- Handgrips, footpeg rubbers, passenger footpeg rubbers
- Mirrors - right has bent bolt, need replacement. Both mirrors need new compression tubing.
- Front right turn signal: replace reflector
- Rubber washers for headlight nacelle side mounting bolts.
- Mounting rubber for front of tank
- parts to rebuild petcocks (Capital Cycle; instructions on Snowbum site)
- Exhaust crossover pipe; old one is rusty.
- 3 feet fuel lines; 2 inline filters too.
- paper air filter
- Clutch cable, both throttle cables, both choke cables
- 4 Pushrod seals
- 2 head gaskets
- 2 cylinder base gaskets
- appropriate gasket sealer (see Snowbum and Ausherman for details)
- 2 conrod big-end bearing shells
- 4 conrod bolts
- oil filter & gasket
- 2 spark plugs
- magnetic oil drain plug
- crush washers for crankcase, transmission, drive shaft and rear drive fill and drain plugs
- clutch parts, TBD
- 4 trans output flange bolts
- 2 retaining clips for piston pins
- new SS exhaust system (lots of dents and rusty bits, crossover tube especially bad)
- 4 pushrod tubes (these ones have lots of rusty spots)
- 5-speed trans - cost?
- electronic ignition (read about it)
- Hook up with local community to see if I can borrow local tools, access specialized advice.
- Saddlebag mounting frames: They are galvanized but it's fading; consider painting or powdercoating.
- Tank needs to be totally cleaned; sandblasted; dents filled; painted and pinstriped. Who can do the cleaning? Who can do the painting?
- Turn signal stems/brackets all have bits of rust. Sandblast/Powder coat? Paint? Re-plate? Replace?
- Professional service performed on both heads
- Inspection / diagnosis of transmission
Work To Do After Inspection
- Clean everything. How to clean up the dirty aluminum heads, cases etc.? Working with Simple Green but I think something more will be needed.
- Measure everything I've got a spec for
- Pull apart every electrical connection or device, clean with good contact cleaner, then apply some dielectric grease.
Record of Work
November 1, 2008
- Removed tank, drained it, removed petcocks and screens.
- Removed saddlebags and attachment brackets, and luggage rack, and seat.
November 8, 2008
- Received tools (exhaust nut wrench, swingarm socket, generator removal bolt, torque extender for flywheel bolts) from Northwoods Tools yesterday, and bought Honda moly lube for splines, and brass brushes for cleaning.
- Drained engine oil.
- Removed exhaust system, fuel lines, air cleaner cover, air cleaner, carbs and intake tubes, main and passenger footpegs, valve covers, rockers, pushrods, heads, cylinders.
Posted a message to the airheads/5united list asking for input and suggestions, which are incorporated in this diagnosis: Air cleaner VERY dirty, oily soot in compartment, and breather tube had belched some oil. Valves don't leak kerosene through but still could have worn guides; will need to send the heads to a pro for evaluation and work. Pistons a bit coky on the top but can remove and clean myself. R side connecting rod has a little fore-and-aft play but basically seems to be good. L side connecting rod has about 1 mm of definite (click-click) in-and-out play, almost as if someone put it together with the wrong size bearing, and will need to be removed and checked. Everything needs thorough cleaning. Piston rings need removal before piston cleaning, then cylinder wear and taper, piston wear, clearances have to be checked.
November 9, 2008
- Removed pistons and measured big-end axial clearance. Ordered a connecting rod bolt removal tool. Will need new connecting rod bolts.
- Called around for estimates on the head work. Kevin Brooks can do it, needs a couple of months. Tom Cutter needs about 8 weeks turnaround time. Boxers by Bruce redirects me to Memphis Motorcycle Works. Mike Wilkes at Memphis says $420 for basic job (regrind, new guides), more if new valves and springs needed which seems likely, turnaround 3 days. So I'll send them to Memphis.
November 22, 2008
- Sent the heads to Memphis (on November 19).
- Got conrod bolt tool and some plastigage from NAPA; removed left conrod. Crankshaft pin seems to be right on spec. Big end bearing beat up; scored, some metal scraped off; see photos. Bought some plastigage, but for sure will need new big end bearing on left side. Should post photos and ask what to do. Meantime can remove other conrod and plastigage it.
- Removed all cables. Most if not all need replacement.
- Removed switches, then handlebars. Handlebars need replacement. See Duane's page at http://w6rec.com/duane/bmw/control/index.htm on controls and cables (also have a Word file of it). Also see his perch wedge page at http://w6rec.com/duane/bmw/perch/index.htm. I think my perch wedges are missing.
- Removed all turn signals, taillight, labeled all wires, made drawing of taillight wire connections. Need new attachment bolts and turn signal lens screws.
- Removed oil filter. Need a new one; also need the cover gasket. No traces of metal in oil filter, but it may have been replaced pretty recently.
- Removed both fenders. Need new bolts.
- Removed clutch actuator arm. Haven't inspected yet; need new cotter pin. Matt Parkhouse has a page on this and its throwout bearing at http://www.airheads.org/content/view/212/98/ and see http://bmwmotorcycletech.info/inputsplinesthrowout.htm for Snowbum's page on splines, clutch arm and throwout bearing.
- Drained drive oil; oil clean, seems pretty fresh. No grit, a little fine sediment after it sat overnight.
- Disconnected drive shaft at transmission output flange. Need new 12-sided bolts. The ones I took off had lock washers; Snowbum says they shouldn't, makes a big deal of it, see his page at http://bmwmotorcycletech.info/drvshftboltstoolstorque.htm.
- Removed shocks. Dirty and rusty. Bolts need replacement. No covers. Maybe need rebuild, don't know yet. They're original. Duane has a page on shock disassembly here: http://w6rec.com/duane/bmw/shock/index.htm.
- Removed swingarm adjusters, removed swingarm/bevel drive/driveshaft as a unit. Deal with it later. Duane has a page on swingarm adjustment at http://w6rec.com/duane/bmw/clutch/index.htm and a page on final drives at http://w6rec.com/duane/bmw/clutch/index.htm.
- Removed transmission. It comes out on the left, very tight fit. Clutch splines clean, not oily, not worn, not rusty. See Duane's page at http://w6rec.com/duane/bmw/trans/index.htm before pondering the tranny.
- Looking ahead to clean up trans, and clutch work - see http://www.airheads.org/content/view/241/98/ for a clutch replacement account, and http://bmwmotorcycletech.info/clutch.htm for Snowbum's clutch page. Also see Duane's page on clutch removal, inspection and repair at http://w6rec.com/duane/bmw/clutch/index.htm.
- Also need to measure cylinder wear. See Duane's page here: http://w6rec.com/duane/bmw/piston/ringtool.htm.
November 23, 2008
- Removed engine. Need new spacers for rear engine through-bolt.
- Cleaned tranny and engine, and cylinders, and various other parts.
- Both sidestand and centerstand need overhaul.
October 25, 2014
Well, this is a postscript to the rest of this page, which otherwise hasn't been touched since the start of 2009. I still have the airhead and it continues to be restored. Each winter some things get fixed, and each summer some riding gets done. At this point I have about 6,000 miles on the rebuilt top end, and it's been to two BMW national rallies and a local one (actually they were all local - trips up to 1,500 miles total). The big things this winter will be a rebuilt Motometer, a new timing chain, refurbished Wixom bags with custom paint, and centerstand repairs. The bike is a blast to ride and gets a lot of compliments - I'm posting a photo here (at left) from the spring of 2009, when it reached more or less its present appearance. I'm not going to continue the repair narrative here, though, because other folks have put a lot more passion into their airhead restoration web page than I am ever likely to. I particularly recommend 1971 BMW R75/5 Motorcycle Restoration, which is my first go-to source when something has me flummoxed. I also recommend 1973 BMW R75/5 Rebuild, as well as Duane Ausherman's and Snowbum's sites, cited above.
The last significant upgrade was a new wiring harness. This I highly recommend. They are cheap, like $85 for the main harness, from BMW. Much easier than trying to troubleshoot 45-year-old wiring. Also, at this point, the entire electrical charging system has been replaced - new diode board, rotor upgrade to 280W output, new solid state regulator, new coils, and a new Odyssey gel-cell battery. I've also redone all the wiring in the headlight bucket and installed a keyed ignition from Rocky Point Cycle. The electrical system work has done wonders for the bike's overall smooth running. Once the new timing chain is in place, it should be capable of new-bike performance.
December 17, 2016
At this point I am nearing the end of what I really regard as the first year of riding the airhead. Following the last update to this page, I determined that the timing chain was pretty worn, to the point where the bike could not really be accurately timed. In the winter of 2014-15 I replaced it, using information readily available on the web (sites mentioned above). It was expensive, requiring about $400 in parts. Following that, I still was getting all sorts of grief from the carbs. I finally gave in this spring and took it to Jason Metzner, airhead mechanic extraordinaire in Tacoma, WA (find him on Craigslist). Wow! Once Jason had everything dialed in, the bike both looked and acted like a brand-new 1970 R75/5. It's quick, powerful, and a blast to ride. I put 7K miles on it this summer without any issues. Real-world problems kept me from doing any long rides (I think the longest this year was 1,200 miles), but I wouldn't hesitate to take it on a transcontinental trip, and hopefully will manage something of that sort next summer. As it is, the bike is my daily rider any time the weather is dry and the temperature is above freezing; beyond those criteria, I still prefer something with a fairing. It's like a time machine, riding around on (mostly) half-century old technology. The bike is gorgeous, everyone loves it, and though it looks like a museum piece, it delivers performance that is still pretty strong by modern standards - it won't dust a GSXR, but it actually performs quite well alongside of midsize standards like a Vstrom or a KLR. It is definitely the most fun ride I've ever owned, enough that I've now sold my GS and my RS, leaving this as the sole BMW in the garage.