Shop engine parts for classic Norton Commando 750 and 850 twins and related Atlas models. The range covers pistons and ring sets, Superblend main bearings, big-end shells, and Kibblewhite valves and guides. You’ll also find valve springs, pushrods, rocker spindles, head studs, and Andover Norton gasket sets.
The 750 and 850 Commando engines look alike, but many of their parts don’t interchange. Before you order, check your engine number, capacity and year, plus the current bore and crank journal sizes. The guide below explains what matters.
Norton 750 Commando P11 Inlet Valve G&S UK-Made 1968-1972 PN# 06-4034 V263
$44.15 – $105.28Price range: $44.15 through $105.28
Norton 750 Commando Pistons with Grant Rings PN# 06-0381 06-0952 US
$120.18 – $147.23Price range: $120.18 through $147.23
Norton 850 Commando Grant Piston Ring Set 1973-75 PN# 06-7958 US
$37.41 – $38.19Price range: $37.41 through $38.19
Norton Commando 750 Grant Piston Ring Set PN# 06-0952 US 06-0953 06-0954
$37.43 – $65.37Price range: $37.43 through $65.37
Norton 750 Commando Kibblewhite C630 Exhaust Valve Guide(s) PN# 06-3527 50-0410 50-0411 50-0412
$26.13 – $47.76Price range: $26.13 through $47.76
Norton 750 Commando Kibblewhite C630 Inlet Valve Guide(s) 1968-74 PN# 06-2725 50-0403
$25.12 – $65.85Price range: $25.12 through $65.85
Norton 850 Commando Pistons (2) PN# 06-3838
$83.80 – $99.98Price range: $83.80 through $99.98
Norton Commando 750 Hastings Piston Ring Set PN# 06-0952 06-0953 06-0954 H
$68.25 – $86.64Price range: $68.25 through $86.64
Norton Commando 750 Pistons (2) 1968-73 PN# 06-0381
$86.63 – $87.39Price range: $86.63 through $87.39
Norton 750 Commando Pistons with Hastings Rings PN# 06-0381 06-0952 H
$149.32 – $167.38Price range: $149.32 through $167.38
Triumph BSA Norton Lucas Points Advance Bolt(s) 1/4 inch X 26 TPI CEI PN# 70-5451 E5451
$8.93 – $12.86Price range: $8.93 through $12.86
Norton 750 850 Commando Contact Breaker Points Cover Screw(s) PN# 06-1105
$5.82 – $7.30Price range: $5.82 through $7.30
Kibblewhite Triumph 500 650 750 Valve Keeper Split Collet(s) PN# 71-3748 K 99-0062 WE259 A
$12.09 – $31.74Price range: $12.09 through $31.74
Triumph 650 Bonneville Tiger UK Made Piston Wristpin Circlip(s) PN# 70-6869 E E6869
$6.90 – $12.22Price range: $6.90 through $12.22
Triumph 650 Bonneville Tiger Piston Wristpin Circlip(s) EMGO JCC PN# 70-6869 T E6869
$7.20 – $13.24Price range: $7.20 through $13.24
Triumph BSA 250 500 650 Piston Wristpin Circlip(s) PN# 70-6869 W
$7.78 – $10.03Price range: $7.78 through $10.03
Triumph Norton Universal Valve Stem Seal(s) Kibblewhite PN# TBS-10-0012
$7.35 – $13.75Price range: $7.35 through $13.75
Norton Commando Intake Valve(s) Kibblewhite PN# 06-4034 50-4092
$35.21 – $66.41Price range: $35.21 through $66.41
Table of Contents
What Makes a Norton Engine Different
The Commando engine developed from Norton’s long-stroke parallel twin, by way of the Dominator and Atlas. The 750 uses the Atlas dimensions, 73 × 89 mm (745 cc). The 850, introduced for 1973, bores the engine to 77 mm, giving 828 cc (Wikipedia: Norton Commando; Norton Owners Club history). The difference matters for nearly every top-end part you buy.
750 and 850 parts are not interchangeable
Pistons, rings, head gaskets, base gaskets and top-end gasket sets are all specific to capacity. Compare the 750 copper head gasket (1968–73) with the 850 copper head gasket (1973–75). Likewise, compare the 750/Atlas base gasket with the 850 base gasket. On the 850, Norton also strengthened the bottom end and used longer cylinder fixings (Wikipedia).
Main bearings have a history
Main bearing failure was the Commando’s best-known weakness, and it got worse with the high-compression Combat engine of 1972. Norton’s fix was the “Superblend” roller bearing, with slightly crowned rollers that tolerate crankshaft flex. It was introduced by service release in 1972. FAG’s NJ306E type later became the standard fitment (RealClassic; Greg Marsh Commando ID; Norton Owners Club main-bearing study (PDF)). If you’re rebuilding an older engine, find out which bearings it has now. Don’t assume they’re original.
CN vs C3 bearing clearance
We stock the FAG Superblend in CN (normal) clearance and C3 (greater than normal) clearance. C3 is not a “better” grade. It gives more internal clearance, designed for tight press fits and large temperature differences (Schaeffler bearing data). Builders disagree about which suits a Commando. The Norton Owners Club bearing article argues that extra clearance can reduce crankshaft guidance, while other builders prefer C3. Choose based on your engine builder’s measurements of the crankcase housing and crank journal fits.
Big-end shells must match the crank grind
Big-end shells come in standard, +.010 and +.020 sizes: STD, +.010, +.020 and Andover +.020. These sizes describe how far the crank journal has been reground undersize. Measure the journals, or check the grind size stamped by the machinist. Then confirm running clearance with Plastigauge. The workshop manual says shells are finished to size and must never be scraped (Access Norton forum quoting the manual).
Pistons and rings follow the bore
Pistons and rings are sized to the cylinder’s current bore: standard (73 mm or 77 mm) or an oversize such as +.020 or +.040. Check the bore measurement against the size marked on the piston crown (Andover Norton piston drawings). We offer UK-made Hepolite, Hastings and Grant ring sets, and the listings show which bore each fits.
The top end has Norton-specific details
- The rocker spindles have an oil feed. On high-pressure-fed Commando heads, the spindle drilling orientation affects how much oil reaches the head. Follow the manual or the instructions supplied with positive-location spindle kits (Norton Owners Club forum).
- Head nuts and bolts face both up and down. The one behind the engine is hard to reach, so Andover Norton sells a special obstruction spanner.
- Valve guides come in standard and oversize outside diameters. For example, the Kibblewhite C630 inlet guides are offered in standard, +.002 and +.004 sizes. Choose the size that suits your head’s guide bores.
Wet sumping is normal, not a fault on its own
A Commando’s oil tank sits above the pump, so oil can drain slowly into the crankcase while the bike stands. Norton added an anti-drain valve in the Mk3 timing cover (Wikipedia). Fitting an aftermarket anti-drain valve is a choice some owners make, but opinions differ. Fit it carefully, and make sure the oil line downstream of the valve is primed (Norton Owners Club forum).
How to Choose the Right Norton Engine Parts
- Identify the engine. Record the engine number, model (Atlas, 750 Commando, Combat, 850 Mk1/Mk2/Mk2A/Mk3) and year. An Andover Norton parts drawing or the Greg Marsh model guide helps confirm this.
- Confirm capacity. A 750 has a 73 mm bore family and an 850 has a 77 mm bore family. Engines are sometimes swapped or converted.
- Measure before you order. Measure the cylinder bore, crank journals (for big-end shell size), valve guide bores and valve stems.
- Decide the scope of the job. For a top-end refresh, you’ll want a 750 top-end gasket set or an 850 top-end gasket set, plus valves, guides and seals. For a full rebuild, add main and big-end bearings, the oil seal kit and engine and gearbox gaskets.
- Match the brand to your goal. Genuine Andover Norton parts, made to original factory drawings (Andover Norton), suit originality. Kibblewhite valve-train parts, such as Black Diamond valves and premium springs, suit durability-focused upgrades.
- Get the right manual. You need a Norton workshop manual and a Norton parts book for torque values, sequences and clearances.
Shop Norton Engine Parts by Type
Pistons and rings
- 750 Commando pistons (pair), 1968–73
- 750 pistons with Hastings rings
- 750 pistons with Grant rings
- 850 Commando pistons (pair)
- 750 Hepolite ring set, UK made
- 850 Hepolite ring set, UK made
- 750 Hastings ring set
- 850 Hastings ring set
- 750 Grant ring set
- 850 Grant ring set
- Piston ring installation tool
Crankshaft bearings and bottom end
- FAG Superblend main bearing, CN
- FAG Superblend main bearing, C3
- Big-end shells: STD, +.010 and +.020
- Plastigauge kits: PL-A, PL-B and PL-C
Valves, guides and valve train
- Kibblewhite intake valves
- 750 inlet valves, G&S UK made, 1968–72
- Kibblewhite C630 exhaust valve guide
- Kibblewhite universal valve stem seals
- Hepolite valve spring set
- Kibblewhite chrome-moly pushrod set
- Valve adjuster nuts (4)
- Stainless rocker spindle set
- Rocker inspection cover set
- Rocker oil feed pipe assembly, 1968–75
Gaskets, seals and fasteners
- 850 Mk2/Mk3 top-end gasket set (Andover)
- Timing cover gasket, 1962–75
- Outer gearbox cover gasket
- Stainless head bolt and stud set
- 750/850 Mk1–Mk2 stainless Allen screw set
- 850 Mk2/Mk3 stainless screw set
Points covers and ignition-side hardware
- Laser-cut logo alloy points cover, 1971–75
- Domed alloy points cover, 1971–75
- Points cover with screws
- Points cover screws
- Lucas points advance bolt (CEI)
Engine mounting (Isolastic)
- Front Vernier Isolastic kit, Mk1/Mk2 (Andover)
- Front Vernier Isolastic kit, Mk3 1975
- Rear Vernier Isolastic kit, all Commandos
These kits are listed here because the Isolastic mounts carry the engine. The front Vernier kit for pre-Mk3 Commandos requires an unmodified front engine mount (Andover Norton drawing).
Installation and Usage Tips
- Head gasket and torque. Fit the short center head bolt first. Tighten in the manual’s sequence, typically 30 ft-lb for the 3/8″ fasteners and 20 ft-lb for the 5/16″. Re-torque after 100 and 500 miles (Andover Norton head-sealing guide (PDF)). Torque the base nuts in stages, following the sequence for your engine (Greg Marsh torque chart (PDF)).
- Copper head gaskets. Use a new gasket, and anneal it if the instructions say to. Don’t reuse one that has been crushed.
- Bearings. Fit Superblend mains with the crankcase heated evenly, never by hammering. Check crank end float. Measure big-end clearance with Plastigauge, and use new rod nuts if the manual calls for them.
- Rings. Check the end gap in the bore, and stagger the gaps around the piston. Fit the rings with an installation tool to avoid breaking them.
- Valve guides. These are an interference fit, so heat the head when fitting them. Then ream or hone to the stem clearance the supplier specifies, and re-cut the valve seats so they’re concentric with the new guides.
- Rocker spindles and feed pipe. Fit new sealing washers. Check the spindle drilling orientation and the rocker feed banjo torque.
- First start after a rebuild. Prime the oil system and check that oil returns to the tank. Also check the oil level after the bike has stood, because wet sumping can make the tank read low and then overfill the crankcase.
- Isolastics. Set clearance to the manual’s figure. Vernier adjusters make this repeatable. Worn or badly set mounts affect handling, not just vibration (Norton Owners Club forum).
- Use the right tools. Norton engines use Whitworth/BSF and UNF fasteners. Browse our Norton service tools and Norton hardware.
Related Norton Categories
Norton Commando parts · Norton gaskets · Norton oil & air · Norton carburetor · Norton electrical · Norton clutch & primary · Norton transmission · Norton exhaust · Norton frame · Norton hardware · Norton tools · Norton manuals · Norton parts books · About the Norton Commando
Further Reading (external)
- Norton Commando – Wikipedia
- Norton Owners Club – Commando history
- Norton Owners Club – Crankshaft main bearings
- Norton Owners Club – Commando main bearing service releases
- RealClassic – Superblend bearings
- Greg Marsh – Commando model identification
- Andover Norton – factory parts and drawings
- Andover Norton – how to seal the cylinder head (PDF)
- Schaeffler (FAG) – bearing internal clearance
- Access Norton forum
Norton Engine FAQs
Are Norton Commando 750 and 850 engine parts interchangeable?
Many aren’t. The 750 has a 73 mm bore (745 cc) and the 850 has a 77 mm bore (828 cc). Pistons, rings, head gaskets, base gaskets and top-end sets are specific to capacity. Many valve-train, rocker and bearing parts are shared, so always check the listing.
What is a Superblend main bearing?
It’s a roller main bearing with slightly crowned rollers, which tolerate crankshaft flex. Norton adopted it in 1972 to fix main bearing failures, especially in Combat engines. FAG’s NJ306E type became the standard Superblend.
Should I buy the CN or C3 Superblend?
CN is normal internal clearance, and C3 is greater than normal. Builders disagree on which is best for a Commando. Choose based on the measured housing and crank fits, and on your engine builder’s preference.
How do I know which big-end shell size I need?
Measure the crankpin journals, or check the grind size from the last rebuild. Standard shells fit an unground crank, and +.010 or +.020 shells match a crank reground by that amount. Confirm clearance with Plastigauge.
How do I choose piston size?
Measure the cylinder bore. Standard is 73 mm on a 750 and 77 mm on an 850. Oversize pistons match a rebored cylinder, so order the size the bore was machined to, or will be.
Hepolite, Hastings or Grant rings: which should I buy?
All three are sized for the Commando bore listed. Hepolite is the UK-made original-equipment brand. Choose by availability and preference, and always check the ring end gap.
What head gasket should I use?
Use the copper gasket for your capacity: 06-4071 for the 750 (1968–73) or 06-3811 for the 850 (1973–75). The top-end gasket sets include the matching head gasket.
How tight should Commando head bolts be?
Factory figures are generally 30 ft-lb for the 3/8″ fasteners and 20 ft-lb for the 5/16″, tightened in sequence. Re-torque at 100 and 500 miles. Always follow your workshop manual or the instructions supplied with aftermarket head-stud kits.
What is wet sumping, and should I fit an anti-drain valve?
Wet sumping means oil drains from the tank into the crankcase while the bike stands. The Mk3 has a factory anti-drain valve. Aftermarket valves are optional and their use is debated. If you fit one, prime the line and follow the instructions carefully.
Do Kibblewhite valve guides need machining after fitting?
Guides are an interference fit and should be sized to the supplier’s stem clearance. Seats should be re-cut afterward. Choose standard or oversize OD to match your head’s guide bores.
Do these parts fit the Norton Atlas or Dominator?
Some do. Items listed for “Atlas, Commando etc.”, such as rocker spindles, valve springs, adjuster nuts, the timing cover gasket and the 650/750 base gasket, cover earlier twins too. Commando-only items will say so.
Why are Isolastic kits in the engine category?
Isolastic mounts carry the engine, gearbox and swingarm assembly in the frame. Worn or badly set mounts cause vibration and poor handling, so they’re often replaced during an engine rebuild.
What tools do I need for a Commando engine rebuild?
You’ll need Whitworth/BSF and AF spanners, a torque wrench, Plastigauge, a ring installation tool, and Norton-specific pullers and holders. You’ll also need the workshop manual for clearances and sequences.
Are genuine Andover Norton parts different from aftermarket parts?
Andover Norton makes Commando and Dominator parts from the original factory drawings. Aftermarket brands such as Kibblewhite offer alternative materials and upgrades. Choose based on whether originality or modification is your goal.