Norton Commando Engine Removal
Article by Mark Trotta
The Norton service manual describes in detail how to remove an engine, but assumes you have an assistant and a fully-equipped shop.
If you're tackling the job single-handed, you'll need an alternative way.
**************
Getting Started
After the gas tank, seat, air box, carburetors, exhaust, head steady, and electrical wiring are out of the way, remove the cylinder head and barrel. The motor is now light enough for one person to lift it out of the frame.
The work stand in my garage was not available for this project, so work was done on ground level. The bike was positioned so that both sides could be gotten to easily.
Read: Commando Cylinder Head Removal
The cylinder barrel was unbolted, but left in place until the engine was nearly ready to be lifted out of the frame. This was done to prevent anything from falling into the motor.
Left and right side Z-plates unbolt easily.
**************
Battery Tray Removal
Removing the battery tray allows better access to the rear engine mounting bolts.
On this 1974 Roadster, there are seven (!) tabs and brackets that need to be unbolted.
This includes the long rear mount stud (pictured above).
Once all tabs and brackets are free, battery tray assembly can be pulled forward, then out the left side.
Oil Tank and Hoses
To help reassembly, pictures were taken of where the three oil hoses started and ended, plus how they were routed.
The oil tank was left on, but mounting bolts were loosened to give a little wiggle room.
**************
Primary Transmission Removal
The primary transmission on Norton Twins is comprised of alternator and rotor, engine sprocket, clutch, chainwheel, and primary chain.
Read: Clutch Removal Norton Commando
After the clutch, stator, rotor, and engine sprocket are off, primary chain, engine sprocket, and chainwheel come off together.
Read: Primary Chain Removal
**************
Inner Chaincase
The inner chaincase is attached to the motor with three 1/4-20 x 9/16" bolts.
Each bolt has a locking plate.
Pictured: Inner and outer chaincase covers. Outer cover has been wet-sanded and awaiting buffing/polishing.
************
Engine Mountings
To keep the motor from dropping, an automotive scissor jack was placed underneath for support. Blocks of wood will also work.
The cylinder barrel was now taken off, which lightens the motor considerably.
Small lengths of automotive radiator hose were slipped over each connecting rod to protect them from nicks and scratches.
Front Engine Mount Bolt
The bolt that goes through the front Isolastic mounting can now be pulled out. The mounting bracket will stay attached to the motor.
Rear Engine Mounting Bolts
Lastly, the three cross-bolts in back of the motor/front of cradle.
Two bolts are 3/8" UNF x 4-1/4"
One bolt is 5/16" UNF x 4-1/4"
A drift pin and hammer was needed to knock the bolts through the cradle. The engine was now free to be lifted out.
With the top of the motor off, the weight of a Commando engine isn't too bad for one person to handle.
************
Notes and Misc
Temporarily reinstall the three chaincase bolts, or any residual engine oil will leak out of the threaded holes.
No need to thread the bolts all the way in. If you do, they'll hit the flywheel.
Read: Remove Commando Gearbox
Find a safe spot to keep all the old parts.
Rolling storage box, aka my 1961 Servi-Car
************
Related Articles:
Norton Commando Build - Homepage
Remove and Install Isolastics
Sludge Trap Cleaning and Crankshaft Reassembly
Bottom End Assembly
Timing Cover Removal and Installation
Remove Cylinder Head
Norton Commando Upgrades
