Motor started life as a 1975 MKIII complete. Purchased on eBay. SN: 331484
Only the crank, cases, oil pump and timing gears were retained.
New F.A.G. NJ 306e "Superblend" main bearings used
Mick Hemmings PW3 camshaft used
New camshaft bushes used – reaming on Bridgeport mill necessary to fit
Some meat necessary to be taken out of cases to allow for high-lobed camshaft
*Some shimming necessary on inner races of bearing on crank pins to achieve .015 endfloat
*Crankshaft magnafluxed, balanced and blueprinted from Lindskog Balancing, Fall 2002
*Balance factor set to 84% as per Mick Hemmings recommendation (stock Atlas BF) 2002 - 2005
Balance factor set to 74% with addition of Steve Maney Crank, 2006, onwards
Four .030 shims inserted behind main bearings (behind each inner and outer) to accommodate MK3 crankcases which are .120" wider than all other Commando cases.
End float = .007" cold.

Crankcase Specs:
• Type: 1975 MKIII Commando
• Main Bearings: F.A.G. NJ 306e "Superblend" (Note: Superblend is a marketing term used by Norton and means nothing to a bearing supplier)
• Cases slightly ground out at mouth for hi-lift camshaft clearance

Crankshaft Specs as of 2006:
• Type: Steve Maney Lightweight
• Build Notes: High tensile steel flywheel, forged cheeks, total weight 14.8 lbs.
• Balance Factor: 74%

*Crankshaft Specs to 2005:
• Type: Commando MKIII
• Build Notes: Magnafluxed, balanced. 1”x .700 Mallory Slugs inserted into cheeks. Slightly lightened. Journals (one was oversized) polished to correct size and taper at 1.750. Lindskog notes: Crank is “Sweet”. MK3 runs 3/8” bolts as opposed to 5/16” on older Commandos. Factory stamped “A” next to one hole in crank.
• Runout of shafts: Timing side = .002, Drive Side less than .001
• Balance Factor: 84%

Camshaft Specs:
• Type: Mick Hemmings PW3
• Inlet valve opens 50° BTDC, closes 82° ATDC (taken at valve)
• Exhaust valve opens 84° BTDC, closes 48° ATDC (taken at valve)
• Inlet valve lift @ TDC = .145” (taken at pushrod)
• Recommended valve to piston clearance = .060 (intake and exhaust)
• Minimum of .050” travel to coil bind necessary on valve springs.
• Inlet tappet clearance = .011"
• Exhaust tappet clearance = .011"

Connecting Rod Specs:
• Type: Carrillo Steel, standard stroke 89mm
• Rod Weight: 468.4g
• Rotating Rod weight: 335.0g
• Reciprocating weight: 133.4g
• Big End Bearings: Commando plain, standard grind size
• Big End Bearing weight: 40.0g
• Bolt Stretch recommendation for torquing between .005” and .007”

Piston Specs:
• Type: JE Forged Aluminum
• Bore: Standard (73mm)
• Piston Weight (including wrist pin and clips): 298.8g
• Ring Weight: 18.6g

Cylinder Specs:
• Type: Mick Hemmings Through-Bolt 750cc
• 73mm bore
• Bored & Honed to match pistons
• Head Gasket: Copper
• Base Gasket: Composite
• Tappets: standard
• Pushrods: shortened alloy

Cylinder Head Specs:
• Type: Mick Hemmings custom Big Valve 750
• Valves: Oversized & reangled valves
• Guides: Custom bronze
• Keepers: Titanium
• Springs: W&S Racing
• Rockers: polished and lightened
• Surface skimmed -.040" for high compression
• Complete porting to Hemmings’ specs
• Polished inlet tract
• Inlet size: 33mm
• Steve Maney custom exhaust, 2-into-1
• Mikuni 35.2mm bored racing carbs
• Custom inlet manifolds