850 MK II Commando Reliability?

I am in the process of purchasing a very clean '74 850 MK II. It needs a little TLC to make it shine, but over all the bike seems to be in a ready to ride condition. (After a thorough once over that is)



Here is the description that was posted on the Craigslist ad which has now been taken down since we have a purchase agreement. Note the electronics upgrades. already present.

1974 Norton Roadster #307907 Mfg. 9/73 Custom, Beautiful numbers matching machine in metal flake blue. Tri spark ignition, Dyna coils. Podtronics regulator/rectifier. Oil pressure gauge installed. RH10 Head. Stainless steel rocker feed lines and new fuel lines. Twin pull twist grip. BAP fuel taps. CNW oil tank modification. NOS primary cover. The rear transmission cradle has an vernier isolastic system. Smith’s instruments with polished clock holders. MK3 kickstart lever. Mk3 head steady. Central Wheel rims, 19” front, 18” rear. Hagon shocks. Lucas turn signals and headlight. Two sets of keys. Some of the items listed are new and some are used, which means some parts may need to be adjusted or fixed. This is a used motorcycle so there are nicks, rust, scratches, and blemishes. Tons of records. TMU. 8155 Miles indicated.“Clear” NYS Title in my name. $8500

At first I was envisioning short day trip rides into the Adirondacks, but after reading about the various Norton enthusiast groups and their rallies, meets, etc. I'm beginning to think about longer trips . I feel like I am physically capable of riding 300-400 miles in a day staying to older state and US highways to avoid the boredom and stiffness associated with interstate travel on a motorcycle.

I am a capable Limey bike mechanic having leaned about Lucas electrics, Amal carburetors and Whitworth/British standard fasteners while I owned a '67 BSA Thunderbolt. During that period I learned how unreliable Lucas electrics can be as well as the parts failures associated with vibration. Since this bike has the Lucas electrics replaced with aftermarket components and the isolastics should reduce vibration associated failures, am I still exposing myself to the likelihood of being stranded hundreds of miles from home with this bike?

How reliable are these particular electronics upgrades? The Podtronics module is cheap enough to carry a spare, but what about the Tri-spark ignition? Does the Isolastic suspension significantly reduce vibration related component failures?

I also want to stress that I am the type that is meticulous about preventative maintenance. Are there any things that I should include in my preventative maintenance drill that would be particular to this bike?

I have owned my 850MK2a since 1982, it had its issues but only once did I need to push it to a repair shop, due to the original harness finally giving up the ghost with an internal break, nearly Honda like reliability if you ignore the routine maintenance and upgrades every Winter. Every other issue has been fixed roadside or driven home with the fault. I have taken it to the IOM and clocked up 2000+ miles in a week, it would do it again.

The engine is rubber mounted, the frame and ancillaries still vibrate until you get to 2500 rpm, worst vibration is at tickover. Plus the engine never stops vibrating, its only isolated from the rest of the bike, so everything connected to the engine will suffer from constant vibration.

In the last year, I have grown a bit of a bad taste for PODtronics. On my bike (with an Alton E-start) it really stifled the power output potential of the alternator (compared to a rectifier / zener diode), and then when I upgraded from a Boyer to a TriSpark EI, the notorious 3000-4000 rpm misfire appeared. So I went back to a rectifier / zener.

I did not see an upgraded alternator listed in your write up. If it is still the RM21, I would consider switching to an LED headlight to reduce the current draw and place it within the capability of the stock alternator. Back when I was running a halogen H/L and an RM21, riding back and forth the 15 miles to work would drain the battery over the course of a week. The bulb is cheaper and easier to install than a 3-phase alternator, and the improved brightness will mean that you will be more noticeable to 4-wheeled traffic during the day, and better night time performance as well.

As far as reliability goes, IMHO, the 1974 850 is the top of the heap. The collective knowledge of all previous Commando's is manifested in this model. And with the upgrades you have listed, there are very few things that you will need to change. Just do your routine maintenance, ride and enjoy.

If there were one thing that I would recommend over and above what you have already listed as complete (not including the front brake as it has already been well covered), that would be an o-ring chain. This involves machining your sprockets 1/8" narrower, and fitting a 520 o-ring or X-ring chain in place of the stock 530. It makes the chain almost maintenance-free. Just lube it now and again.

FWIW

Derek Wilson said:

In the last year, I have grown a bit of a bad taste for PODtronics. On my bike (with an Alton E-start) it really stifled the power output potential of the alternator (compared to a rectifier / zener diode), and then when I upgraded from a Boyer to a TriSpark EI, the notorious 3000-4000 rpm misfire appeared. So I went back to a rectifier / zener.

I did not see an upgraded alternator listed in your write up. If it is still the RM21, I would consider switching to an LED headlight to reduce the current draw and place it within the capability of the stock alternator. Back when I was running a halogen H/L and an RM21, riding back and forth the 15 miles to work would drain the battery over the course of a week. The bulb is cheaper and easier to install than a 3-phase alternator, and the improved brightness will mean that you will be more noticeable to 4-wheeled traffic during the day, and better night time performance as well.

As far as reliability goes, IMHO, the 1974 850 is the top of the heap. The collective knowledge of all previous Commando's is manifested in this model. And with the upgrades you have listed, there are very few things that you will need to change. Just do your routine maintenance, ride and enjoy.

If there were one thing that I would recommend over and above what you have already listed as complete (not including the front brake as it has already been well covered), that would be an o-ring chain. This involves machining your sprockets 1/8" narrower, and fitting a 520 o-ring or X-ring chain in place of the stock 530. It makes the chain almost maintenance-free. Just lube it now and again.

FWIW

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Switching to LEDs was something on my mind as it seemed like a good way to ease the load on the charging system.

13mm MC with SS brake line and upgraded pads are also on the winter lost as well as the anti-sumping and PRV upgrades.

kommando said:

I have owned my 850MK2a since 1982, it had its issues but only once did I need to push it to a repair shop, due to the original harness finally giving up the ghost with an internal break, nearly Honda like reliability if you ignore the routine maintenance and upgrades every Winter. Every other issue has been fixed roadside or driven home with the fault. I have taken it to the IOM and clocked up 2000+ miles in a week, it would do it again.

The engine is rubber mounted, the frame and ancillaries still vibrate until you get to 2500 rpm, worst vibration is at tickover. Plus the engine never stops vibrating, its only isolated from the rest of the bike, so everything connected to the engine will suffer from constant vibration.

Click to expand...

If the bike has the original wiring harness I will probably rewire it from scratch as I am well versed in that subject.. In the early '70s I was the go to guy for Limey bike electrical problems in the Lower Allegheny valley when the local Triumph shop was inept at troubleshooting electrical problems, even when the bikes were under warranty.

Dan1950 said:

If the bike has the original wiring harness I will probably rewire it from scratch as I am well versed in that subject.. In the early '70s I was the go to guy for Limey bike electrical problems in the Lower Allegheny valley when the local Triumph shop was inept at troubleshooting electrical problems, even when the bikes were under warranty.

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A very good idea. Ratty wiring causes lots of issues. Take a good look at the kill button if it's still there and the internals of the main switch. And use a blade fuse. How's do the carbs look,?

The stainless rocker lines are braided ? Check they don't rub the tank because they make a good hacksaw.

Inner layshaft bearing needs checking, do you have this change from ball bearing to roller bearing in the records. If not the gearbox needs opening up. The bearing fails by the cage falling apart, this allows all the balls to drop to one side and then fall out, first sign is the kickstart moving backwards on acceleration, 2nd (or first even) could be the rear wheel locking up. I got mine home by using only 4th gear through city centre on a busy Saturday afternoon, 30 years later the steel plain clutch plates are still blue. When I took it apart there were several split balls in the gearbox sump, no doubt mashed by the gears.

kommando said:

Inner layshaft bearing needs checking, do you have this change from ball bearing to roller bearing in the records. If not the gearbox needs opening up. The bearing fails by the cage falling apart, this allows all the balls to drop to one side and then fall out, first sign is the kickstart moving backwards on acceleration, 2nd (or first even) could be the rear wheel locking up. I got mine home by using only 4th gear through city centre on a busy Saturday afternoon, 30 years later the steel plain clutch plates are still blue. When I took it apart there were several split balls in the gearbox sump, no doubt mashed by the gears.

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The bike supposedly has "tons of records" so I will check. I have heard that the gearbox can be a weak link.

It’s only done 8,000 miles !

If it were me I’d go through the wiring, check all connections etc, perhaps apply dielectric grease to all connectors, replace any perished rubber female bullets etc. But I wouldn’t be re wiring it !

The PODtronics R/R is not perfect, but it's certainly the most popular one on the market. Lots of them in service. I have a Tri Spark ignition on my MKII and I love it. As others have noted, the Lucas bullet connectors should be inspected, which you are familiar with. The stock kill switch is one of the very few things that have left me stranded in the last 46 years of Norton ownership.

Fast Eddie said:

It’s only done 8,000 miles !

If it were me I’d go through the wiring, check all connections etc, perhaps apply dielectric grease to all connectors, replace any perished rubber female bullets etc. But I wouldn’t be re wiring it !

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The description says TMU, 8155 indicated. Besides, the bike is 47 years old.. If the harness insulation is still supple, I'll leave well enough alone. If it is stiff or brittle, I'll re-wire it. (Winter project)

Dan1950 said:

Switching to LEDs was something on my mind as it seemed like a good way to ease the load on the charging system.

13mm MC with SS brake line and upgraded pads are also on the winter lost as well as the anti-sumping and PRV upgrades.

Click to expand...

As far as anti-wet sumping valves go, I can highly recommend the valve from Walridge Motors. It works very well and is very reliable. You already have an oil pressure gauge, which I consider a necessity if you are going to run a AWS valve. With a gauge, you will know right away if the valve has not opened.

Derek Wilson said:

As far as anti-wet sumping valves go, I can highly recommend the valve from Walridge Motors. It works very well and is very reliable. You already have an oil pressure gauge, which I consider a necessity if you are going to run a AWS valve. With a gauge, you will know right away if the valve has not opened.

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Actually I am looking at the AMR modification to the timing case and oil pump.

AMR ANTI-WET SUMP VALVE AND PRV

There is a block connector under the fuel tank that's rubber that I had to address. The rubber pretty much deteriorated to mush.
That would be worth checking. A full fluid check of front forks, transmission, primary and swing arm. You've probably read about the clutch pushrod seal to keep trans oil out of the clutch plates. Swing arm pivot shaft clamps also recommended.
Eventually, the wheel bearings can be replaced with sealed bearings. The AMR mod isn't perfect. I just live with wet sumping anyway. It varies with each motorcycle. The gauge is good to see how much your pressure varies by engine temp.

Fit LEDs all round and fit a tri-spark mosfet rectifier no more problems with your ignition ,and then enjoy your roadster ,remembering the blue ones are the best ones !

Note the Trispark ign has a warning on website around podtronic RegRec giving too much electrical noise, leading to trispark problems. They offer an inline filter for $20 or recommend a different RegRec like their MOSFET.
See Greg Marsh on this site for good pricing on trispark and other parts in the US.

I've had my MKII 850 for four years now. First classic bike for me. Bike had under 8k on clock, now has 15k
In that time I've had a number of failures/issues while out on road. Headgasket, inner primary bolts to casing letting go, zener diode failing leading to a fried battery (original 2MU capacitor let me keep riding home); numerous carb issues (highly recommend getting a Carbtune balancer to nail them down); valve seal leaks; wet sump caused crankseal blown apart; clutch cable broke (rec using one with plastic sleeve on the lever end barrel); exhaust rose nut rattling loose; header cracking at balance pipe branch. Latest issue this week is sudden engine shutdowns at random times (likely electrical issue, hard to pin down).

So yes, reliability can be an annoyance. My bike had been restored at some point in past by another owner, but no records came with it.

My Commando has never left me stranded; it's been as reliable as any other bike I have owned. Requires more maintenance than a Honda but not really all that much once it is checked out and brought up to proper operation/maintenance. That might take a while depending on the condition of the bike when you purchase it.

Re Podtronics - I have had no issue with my Trispark as far as interference. BUT the OEM rectifier/Zener provided a slightly greater battery charging voltage than does the podtronics. If I had it to do over, I'd just leave the rectifier/Zener in place.

The problem with the zener system is finding a good new or replacement zener.

Any bike is only as good/reliable as the previous owner
If built properly a commando is a very reliable bike
Especially the MK2 IMO

baz said:

Any bike is only as good/reliable as the previous owner
If built properly a commando is a very reliable bike
Especially the MK2 IMO

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Motorcycles are only as reliable as the last person that worked on them. I found that to be especially true of pre-Evolution Harley Davidsons. I wrenched on my '64 Panhead in the garage, not on the side of the road.

I plan to do the same with my MK II Commando.