The story of my Norton began over 10 years ago in 1990. A mate suddenly needed some money and wanted to sell his old wrecked Norton. I had hardly any money, and spent it all on my dream bike. A black 1971 Roadster.
The frame was broken, it had no seat and all the Lucas smoke had been let out of the wiring harness. The tank was split in 3 places. It had home-made exhausts, no centre or side stand. Rusty dented mudguards, no instruments or instrument brackets. It had no switch gear, no chain guard, no headlight brackets and no headlight. The gearbox cover was missing, the right foot peg was broken off and the air cleaner was missing. The kick start was stuffed. The head steady was broken. It had no taillight or frame loop, no side covers, and oil was pissing from everywhere. It kinda ran but belched TONS of blue smoke.
I knew then it would never be a low mileage “minter”, so I set out to home-build a “riders bike”; a fast, strong and reliable bike that would out perform any “minter”. I also wanted it to look, smell and sound like a classic. Not really a tourer, more like a thoroughbred sprinter. That’s what I associated Nortons with; racing and going flat out. Also what I enjoy most. I love the look of the Roadster but wanted mine to be at home doing battle out on the race track.
I rebuilt the motor myself with help from my mate Richard. This started with the crank. Epicycle balanced it to 63% from memory. Good balance means a stronger and more reliable donk. I leave the bike parked at TDC to avoid the “sludge” problem. It also seems to help prevent it wet sumping. I polished the conrods and fitted new GPM pistons. Watch your barrel nuts (750 owners), they are known to work loose if you ride your Commando hard or have a high compression ratio.
Brett sold me a Combat cylinder head which I ported and polished. New guides, springs and new valves. Seats were re-cut and I machined half a millimeter off each end of the pushrods to retain geometry. Rockers can be located directly over the centre of the valves with phosphor bronze shims. Ducati valve caps can be used to avoid long term damage to the top of the valve stems. Socket head adjusters make adjusting the clearances easier. I understand the rockers may also be lightened quite a lot.
The camshaft turned out to be a good score. It’s a “Norris SS” performance cam. Ivan Tighe measured it and rebuilt it. It’s been designed for midrange grunt and certainly seems to work OK. I use FAG bearings everywhere and bond the engine cases together using “Three Bond”. Stainless nuts and bolts etc are worth the expense I reckon. I purchased a broken centre stand which I welded up, made some bushes and bolted on. I use a home-made race stand in the workshop to avoid stuffing the rear isolastic.
I rebuilt the gearbox and bought a smashed set of instruments and a set of headlight brackets at a swap meet. KTT rebuilt the clocks better than new. I made my own wiring harness and later relocated the ignition switch to the dashboard.
Anderson Engineering made me a new frame loop and I welded it on. A new seat and 2 stainless mudguards followed. Steering head bearings are tapered rollers top and bottom. There’s no place for ball races in steering heads for lots of reasons.
Now to the carby’s. Remember acceleration has an inverse relationship to the carby bore. Big carbs are only good for breaking land speed records. Brett came to the rescue with a single manifold. A 34mm Mikuni came from Sydney Motorcycle Wreckers and I run a “K & N” air filter. Now this seems to make for serious reliability, easy starting and huge midrange torque. I don’t reckon single carbs sacrifice top end power. Twin carb Nortons didn’t seem to reel me in down the straight at Eastern Creek at the ride day.
A Boyer takes care of the ignition and I got a Norvil type head steady. I fixed the tank and a mate painted it with Glasurit. I painted the side covers and tail fairing. Castrol GP50 (25w 50) mineral oil has always lubed the motor. I’m thinking of changing to a 15w50 synthetic like Mobil 1. I run Konis on the back and modified the cradle spindle with securing bolts each side that clamp the spindle tight into position.
Originally I tried everything to sort the Road holders and the TLS. Some small improvements were made but my Road holders were never in the ball park. I feel like I could write volumes here but Road holders are fundamentally flawed for many reasons.
Richard found me the 38mm Ceriani front end off a Duke at a swap meet. Gowanlochs machined the spindle and I had a pair of 280mm Brembo discs and “08” Brembo Calipers. Gowanlochs made the braided hoses. I use a 5/8’’ (15mm) Brembo master cylinder. I bought the 18” shouldered Akronts and duke speedo drive. 750ss instrument brackets hold Norton instruments. BMW headlight brackets look sort of like Norton bits but fit over the 38mm stanchions. The stainless front guard is off a Laverda.
This front end gets me out of trouble rather than into trouble. The steering is tighter, sharper and predictable. It tracks beautifully and doesn’t get itself out of shape during braking or going over bumps.
I welded a gusset plate under the steering head between the down tubes to help take the extra braking loads. Laverda handlebars give me an adjustable “clip on” type riding position. I home-made a Duke type steering damper set up.
The back end is a 200mm Grimeca with 2.5” x 18” shouldered Akront laced with 3.5mm stainless spokes. The one-piece axle is off a Kwaka although a duke axle will fit. I opened the swing arm slots to 17mm to allow for the new axle and welded anchor plates onto the front of the swing arm which hold the brake plate in situ. I machined the sprocket carrier to keep the correct offset from rim to drive. I made stainless axle spacers and found some Laverda chain adjusters which make chain adjustment a pleasure.
The back brake has a crossover shaft which connects to the Grimeca hub. The mechanical advantage is adjustable to the sort of feel that you prefer. The rearsets and low bars mean a better riding position if you like going for it. Easier to steer and move the weight around on the pegs and better for getting down out of the wind.
I haven’t found tyres that are better than 18” Pirelli Match. 100/90/18 on the front, 120/90/18 on the back. There’s a lot to be said for modern tyres. They’ve sorted things in a big way. Don’t go larger than 100 / 90 / 18 on the front cause it seems to make the bike tanky.
The stainless steel chain guard is home-made to look like a Norton one. I always use Regina chains and have never had one snap or come off.
The rearsets are all homebuilt from stainless. The foot pegs fold up and the gear change lever is “hooked” so the kick start can still be retained. I have a reverse gear pattern so it’s the same as my other 2 bikes. The grabrail is home-made from a piece of tube slightly larger than the standard affair.
Current gearing is 21t on the gearbox and 37t on the back wheel. Nortons have plenty of torque so you can gear them tall. Bottom line is never over-rev a pushrod long stroke. I hit about 115 Mph (185k’s) down the straight at Eastern Creek at about 5700rpm. She was still accelerating hard at that speed. I reckon it will do 125Mph (200k’s) on a decent run. Not bad with a single carby and more than enough speed for me.
Future plans include thermostatic oil cooler, a belt drive primary and redesigned (perhaps tapered roller) swing arm set up. Those twin Keihin flat slides of Kenny Dreer’s seem OK, would give you the best of both worlds. Keep on polishing those engine covers – gives you time to think.