Norton Commando Technical

Engine
	750	850
Capacity	745cc (45 cu. in.)	828cc (50.5 cu. in.)
Bore	2.875 in. (73mm)	3.030 in. (77mm)
Stroke	3.503 in. (89mm)	3.503 in. (89mm)
Max. Torque(5000 rpm)	48 lb./ft. (Combat 49lb)	56 lb./ft.
Compression Ratio	9:1 (Combat 10:1)	8.5:1
Maximum Speed	112 MPH (Standard)	122 MPH
Spark Plug	Champion N7Y or Equivalent.
Spark Plug Gap	.023 - .028 in.
Contact Breaker Gap	.014 - .016 in. (Click here for Boyer Ignition)
Ignition Timing	28 degrees BTDC (Fully Advanced)
Valve Clearances (Cold)	750	850
Inlet	.006 in. (Combat .008)	.006 in.
Exhaust	.008 in. (Combat .010)	.008 in.
Camshaft Chain Adj.	3/16 in. (4.8mm) play at top of chain.
Valve Seat Angles	45 degrees inlet and exhaust
Index

Primary Transmission And Rear Chain
Engine Sprocket	26 Teeth
Clutch Housing	57 Teeth
Primary Chain	Triple Row, 92 Pitches, .375in. x .250in.
Rear Chain	99 Pitches, .400in. x .380 in.
Clutch Pushrod Length	9.813/ 9.803 in. (244.250/ 243.996 mm)
Clutch Pushrod Diameter	.237/ .232 in. (6.019/ 5.892 mm)
Clutch Ball Bearing	1/2 in. (12.70) Diameter
Clutch Plates	4 fiber clutch, 5 metal clutch (Sintered Bronze)
Clutch Adjuster	1/2 in. x 20 UNF 2A
Clutch Adjuster Length	.904 in. x .894 in ( 22.962/ 22.708 mm)
Index

Gearbox
Estimated Speeds Using 19-23 Tooth Gearbox Sprockets
Sprocket Size	Overall Gear Ratio	6000 rpm	6500 rpm	7000 rpm
19	4.84	92 mph	99 mph	107 mph
20	4.60	97 mph	105 mph	113 mph
21	4.38	102 mph	110 mph	119 mph
22	4.18	106 mph	115 mph	121 mph
23	3.99	112 mph	121 mph	130 mph
( I recommend using a 20 or 21 tooth sprocket depending on where you live)

Number Of Teeth On Pinions
First Layshaft 28 teeth
Second Layshaft 24 teeth
Third Layshaft 20 teeth
Fourth Layshaft 14 teeth
First Mainshaft 14 teeth
Second Mainshaft 18 teeth
Third Mainshaft 21 teeth
Fourth Mainshaft 23 teeth
Ball Journal Bearings
Mainshaft (Clutch End) 11/4 x 21/2 x 5/8 in.
Mainshaft (Kickstarter) 5/8 x9/16 x 7/16 in.
Layshaft (Clutch) 17mm x 40mm x 12mm
Index

Carburetor And Air Filter with Standard Ex.
Standard 750 (Twin Amal 930 30mm)
	Main Jet	Needle Jet		Needle Position	Throttle Valve
1970	220,180, or 210	.107		Middle	3
1971	220	.106		Middle	3
1972	220 or 210	.106		Middle/ Top	3
Standard 850 (Twin Amal 932 32mm)
Main Jet			260
Needle Jet			106
Needle Position			Top
Throttle Valve			31/2
Needle			928/ 107
Choke Tube			928/ 107
Air Filter			Pleated impregnated paper
*Please note it is best to use Amal Mk 2 Carbs with a K&N Air Filter In My Opinion.
*It is best to use straight through 'Reverse Cone' after market exhausts with these settings
Index

Forks/ Shocks
Forks ( Telescopic with internal Springs Hydraulically damped)
Total Fork Travel	6 in.
Fork Leg Oil Capacity	150 cc in each leg
Springs	75 1/2 Coils
	18.687 in. free length
	36.5 lb./ in
Shocks (Girling Oil filled with External Springs)
Spring Free Length	8.75 in.
Rate	126 lb. per in. (depends on adjustment)
Fitted Length	8.4 in.
Total Length	13 in.
Index

Brakes Wheels And Tires
Front Wheel
Rim Size	WM2 - 19 in.
L.H. Wheel Bearing	17x40x12 mm.
R.H. Wheel Bearing	NM 17721
Spindle	.66671/ 6670 in.
Tire Size	4.10 x 19 in.
Tire Pressure	26 PSI
Tire Diameter	26.46 in. (Dunlop)
Tire Width	4 in.
Front Brake (Disc)
Pad friction area	1.65 in.
Pad Thickness (New with Backing)	.38/ .37 in.
Pad Minimum Thickness	.0625 in.
Disc Diameter	10.70 in.
Disc Width	.260/ .250 in.
Brake Fluid	Lockheed 329 Quality
Front Brake (Drum)
Type	Twin Leading Shoe
Drum Diameter	8 in.
Brake lining area Total	18.69 Sq. in.
Rear Wheel
Rim Size	WM2 - 19in.
Wheel Bearings	17x40x12 mm
Sprocket Bearing	NM 177721
Tire Size	4.10x19in.
Tire Pressure	26 lbs./PSI
Tire Diameter	26.46 in.
Tire Width	4 in.
Rear Brake
Drum Internal Diameter (New)	7.007/ 6.997 in.
Brake lining area Total	13.6 Sq.in.
Index