Saturday 16 May 2020

Norton 850 Commando



Oh for a good British motorcycle, thought I once in a blue moon. I’d been there, done that... on Triumphs, BSAs and Nortons. Gone on to a series of fearsomely fast Japanese fours. But, yet, I still found myself occasionally lusting after some British relic. The UMG reckoned a lot were renovated, revitalized and re-engineered, to quote an unusual amount of enthusiasm. Could it be true, or was it just another media ploy to sell copies? I had to find out.

The classic glossies provided an excess of dealers for me to visit and even some private ads for me to follow up. I even cajoled some tests rides. A Triumph 750 was a rolling massage table, a BSA Spitfire shed parts at an incredible rate and by the time I tried a Norton 850 I was ready to be amazed by its Isolastic absorbed lack of vibration. Hey, I’ll have one of these. Not unless you've got five grand to burn, said the dealer.

Apart from the lack of vibes, I was well taken with the surly torque and stable handling. The bike had the vernier shim conversion which made setting up the Isolastics, so that they both absorbed vibes and held the bike together, relatively easy (as the swinging arm was only connected to the frame via the Isolastic mounts). Oh, yes, it also looked perfect in its classic shape. I had to have one.

The only cheap ones were in a disgusting state. By cheap I mean under 2000 notes. I persevered, being somewhat annoyed with the amount of lies people told over the phone. Eventually, for £3500 I found a 67000 miler, slightly shabby chassis (but with the vernier shims) and a rebuilt engine. I knew it was a good one from the way it came to life first kick, powered us up to 120mph at a rate that would shame many a Jap four, and from the lack of vibes or oil leaks. The owner had kept the bike for ten years, was only selling because the wife had dropped her fifth brat and a Transit van beckoned.

I figured I could do a respray myself and soon have it shining with all the glory of a true Brit. The bike was basically a Mk.3 but with the odd chassis bit off earlier models. Definitely not concours, more your well lived in, cleverly updated and generally sorted piece of tackle. I sprayed her silver grey, polished the alloy, filled the tank, primary drive and gearbox with fresh oil, then headed for the open road.

Around Lancaster way there are plenty of fast back roads, which were taken with aplomb by the charging, snorting Commando. Though in its lack of vibration it was relatively civilised it was still a beast at heart, a raw and raunchy 850cc vertical twin. Masses of torque thrust the relatively light and narrow chassis forwards in a most rewarding and exhilarating manner. It's also one of the few British twins that will reliably canter along at 90 to 100mph, without a deluge of vibration and the old bits falling off routine. In its day, the engine had a reputation for blowing up in a big way when tuned or hard used, but using the later engine parts lovingly assembled removed most of the horrors inherent in an engine that could trace its roots back to a mild old 500cc twin.

So impressive was its general performance and usability that a few Jap replica riders were won over by its brutality. It couldn’t do 160mph but it could get up to 120mph in a relentless and charming way that held the unwary and innocent rider all agog. Wonder was even expressed that the British bike industry went so easily down the toilet. Two friends ended up trading in for Commandos. This unlikely trio was given pause for thought when one of their number (unfortunately, this writer) suddenly found his machine rattling furiously around the top end and smoking away like a 30 year old MZ 150. Surprise was expressed that it didn’t have a camchain tensioner as it sounded just like a CB750F1 at death’s door I once owned.

The noise was coming from a loose exhaust valve guide that was merrily popping up and down in the head. Having removed the cylinder head it seemed like the decent thing to do - to gas-flow it, upgrade the valves and their seats so unleaded could be used as well as adding new valve guides. I did most of the work myself, total cost coming out at £120. The bores and pistons looked just fine, were left well alone.

Unfortunately, the engine pinked disarmingly on unleaded due to the high compression pistons fitted, so the new valves were a complete waste of dosh. Valve guides are something of a weak spot in Commando top ends, can go without much warning. With the gas-flowed head, economy improved from 45 to 50mpg, although performance didn’t increase to any discernible degree - no doubt the poor aerodynamics of a naked machine overwhelming any small amount of extra power that might turn up.

One of my mates engine’s blew up in a big way, as in the con-rod poking out of the crankcase. Turned out he was regularly revelling in taking the engine to nine grand! This is a quick way to reduce a Commando engine to a molten mess however much it has been upgraded or re-engineered. He was led away in tears after this had gently been explained to him. As noted, these machines do indeed get to you.

My motor ran for another 14000 miles, or so, before performance went awry and starting became awkward - not something you want to experience on an engine that needs a real manly kick. I was tempted to blame the electronic ignition, always on the lookout for an easy escape, but, no, a local expert in these matters reckoned on worn out bores. Quite literally as they were already on maximum oversize. A few phone calls to a couple of Norton spares dealers secured replacements plus brand new pistons and rings.

Even after such a low mileage both the valves and the guides were also showing signs of serious wear, so another round of replacements. The crankshaft felt secure on its Superblend bearings but the primary chain and clutch were both well knackered. When it was all sorted out, I’d spent over £450! Meanwhile, my other Commando riding friend had sold his machine at a nice profit, having done 21000 miles with nothing more irritating than regular 500 mile services. But he could tell which way the wind was blowing, realised it was only a matter of time before something nasty went down.

I suppose it depends on how seriously you want to take things. If you’re just after the odd Sunday afternoon outing, the bike will probably last for years but if you’re into heavy riding at reasonable speeds then it can be very quick wearing. Money’s saved on the consumables - I found it very hard to wear out a set of Avons or the cheap and cheerful drive chain, whilst the rather primitive front disc made up for its basic nature by never coming close to wearing out the pads in 18000 miles but that included some hairy moments in the wet.

Not that any of this will stop the true enthusiasts singing loudly their praises because they have a certain character coupled with a great deal of practicality that makes them rather unique in the old British bike game.

A.M.R.