R12 Data Sheet
Main Bearings

Housing Diameter           Front 77mm  ( -0.013 to -0.035)
                           Rear  77mm  ( -0.013 to -0.035)

Bearing Diameter          Front  77mm  (+0 to -0.02 )
                          Rear   77mm  (+0 to -0.02 )

Interference               Front  0.01 to 0.03mm
                           Rear   0.01 to 0.03mm

Side Clearance bearing to flywheel  1.0mm Minimum

Side Clearance Crankshaft Web OR Oil Flinger ring
                   to housing Front  0.6 to 0.8 mm

                               Rear  0.8 to 1.0 mm

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Camshaft

Bore Diameter in Housing or cover  Front 28mm (-0.04 to -0.075)
                                   Rear  22mm (-0.04 to -0.075)

Bush or Bearing body outer Diameter  Front 28mm  (+0 to -0.15)
                                     Rear  28mm  (+0 to -0.15)

Interference                        Front 0.02 to 0.07mm
                                    Rear  0.02 to 0.07mm

Running Clearance                  0.03 to 0.08mm

Side Clearance                     0.05 to 0.1mm

Tappet Diametrical Clearance       0.04 to 0.07mm

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Timing
With 2.0mm valve clearance Another source gives With 0.1mm Valve Clearance
INLET  Opens    17deg       After TDC           20deg or 3mm
       Closes   23deg       After BDC           60deg or 16mm

EXHAUST Opens   23deg       Before BDC          60deg or 16mm
       Closes   17deg       Before TDC          20deg or 3mm

CAUTION!! I AM SUSPICIOUS OF THESE FIGURES, I SUSPECT "INLET OPENS" AND
"EXHAUST CLOSES" MAY HAVE BEEN TRANSPOSED !!

Ignition Timing        12mm or 42deg bBefore TDC

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Lubrication

Test pressure at @250rpm 1.5 to 2Atmos Minimum

Oil Pump side clearance  0.05 to 0.1mm

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Gearbox

Mainshaft Side Clearance 0.1 to 0.5mm
Layshaft  Side Clearance 0 to 0.3mm
Shaft end float  0.1mm
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Gears

1st Running Clearance 0.03 to 0.1mm
    Side Clearance    0.1 to 0.3mm

2nd Running Clearance 0.03 to 0.1mm
    Side Clearance    0.1 to 0.3mm

3rd Running Clearance 0.03 to 0.1mm
    Side Clearance    0.1 to 0.3mm

4th Running Clearance 0.03 to 0.1mm
    Side Clearance    0.1 to 0.3mm

    Run with same clearances.

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Kickstart Shaft
    Running Clearance 0.02 to 0.07mm
    Side Clearance    0.1 to 0.5mm

Kickstart Idler
    Running Clearance 0.03 to 0.1mm
    Side Clearance    0.1 to 0.3mm

Selector Fork
    Running Clearance 0.05 to 0.12mm

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Suspension

Front Fork

Steering head Bearings 20 off 6.5mm diameter balls

Bush running clearance  Top    0.025 to 0.1mm
                        Bottom 0.025 to 0.075mm

Spring wire Diameter    Solo    5.5mm
                        Sidecar 6.0mm

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Rear Wheel Drive

Crown wheel float, upwards   0.1mm  Max
                   sideways  0.05mm Max

Tooth Backlash               0.1 to 0.3mm

Drive Shaft endfloat         0.5mm

Axial Clearance of drive shaft  1 to 3mm