A BMW R100 café racer in a dark workshop, one lamp on the tank
On this benchAn '81 R 100 RT, rebuilt and written down

Every torque spec.
Every airhead.

A workshop reference for the BMW two-valve boxers, 1969 to 1996. Every figure sourced. Every conflict printed. Resolves to the bike in front of you.

Open the book Free to read · Works offline

Three answers to every question.

This is the one with a source.

The torque value in the forum thread, the one in the Clymer, the one Snowbum argues for and the one the factory printed in 1978 are four different numbers. This book prints the factory figure, says where it came from, and prints the specialist deviation beside it, labelled, so the choice is yours and informed. Twenty-six chapters, seven hundred-odd specification rows, seventeen plates drawn for it.

As found

00 · ORIGIN
A red 1981 BMW R100RT with full fairing and panniers, parked on leaves
1981 R 100 RT · as it arrivedWhich one to buy →Fairing, bags, forty-odd years of somebody else's fixes. The plan was a café build. The plan became a full engine rebuild first.

Cases

11 · ENGINE
A bare BMW airhead crankcase mounted on a black steel engine stand in a workshop
The standBuilt for the job. The cases came apart on it and went back together on it.
An aluminium casting being machined, swarf on the mill table
Machined, measured, written downEvery clearance that decided a fit went into the book with its source.

Bottom end

11 · ENGINE
Two connecting rods on a blue shop towel beside a box of Glyco bearing shells
Rods and shellsTorque specifications →New Glyco shells. Plastigauge first, torque second. The rod-bolt figure comes from the factory sheet, and it is the one number you do not guess at.

Clutch

21 · CLUTCH
Clutch pressure plate, diaphragm spring and a new friction disc laid out on blue towels
Laid outNew disc; plate, diaphragm and housing cleaned and checked before they went on.
Close-up of a Bing carburettor with a pod filter on a BMW boxer cylinder
Bing CVJets by carburettor number, not by guesswork. Chapter 13.

Together

00 · THE BENCH
A rebuilt BMW boxer engine on a stand in front of a Hardinge lathe
On the stand, before the frameMaintenance schedule →It sat there a good while before it went into the frame, and longer before it ran. It runs now.

Pick your bike.

Every figure in the book resolves to one model and year. Change the bike and watch the numbers change. These are the book's own values, pulled live from the same tables.

Year
1978
Displacement
Valve clearance, cold
Rear end
Ignition
Final drive fill
Fork oil, per leg
Compression ratio
Cylinder head nuts
▲ marks a value where the factory chart and shop practice disagree, or where the year matters more than the model. The book prints both and says why. Seventy more rows like these, for every model, in My Bike →

Free to read.
$39, once, for your bike.

  1. Read everything. All twenty-six chapters, the search, the plates and the gallery are open to anyone, with no account.
  2. Set up your bike. Type the frame number or pick the model and year. One payment, your name on the licence, three devices.
  3. Every figure resolves. Capacities, clearances, timing marks, the one-page torque sheet, thirteen job pages, the printable booklet, a service log that lives on the phone.
  4. No signal needed. It works under the lift, in the shed, at the side of the road. The licence is yours; nothing phones home.

Twenty-six chapters.

The BMW roundel on a black tank, in shadow

Open the book.

Written in a fabrication shop in New Jersey by someone rebuilding an '81 RT, from the factory manuals, the specialists, and the bikes on the bench.

Open the book@airheadreference Free to read · $39, once, resolves it to your bike · Works offline