Motorcycling

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The newest ride, a 1970 BMW R75/5 with my daughter, the day I bought it.

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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.

Tools Needed

  • 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.

Parts Needed

CHASSIS

  • "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

POWER TRAIN

  • 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

WISHFUL THINKING

  • 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)

Services Needed

  • 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

See photos.

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

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.