Expected Engine Wear

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Is there agreed wisdom on how many miles you can put on a Norton engine before it requires major engine work?
For example, how many miles before you need:
-new rings, pistons, or a rebore?
-new valves or guides?
-bottom end work, such as big end shells?

I appreciate this is a pretty fuzzy question and the obvious folks in the crowd will say "your mileage will vary".
But making a few basic assumptions, such as:
-regular maintenance
-not riding the bike like you stole it
-no defective parts from factory like soft cams, slotted pistons, etc etc,

Are there some ball park mileage numbers that we can generally agree on???
 
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Have about 27,000 on my '74 850.... burns a little oil - no smoking though. Still runs strong and smooth. Stored many years, but always oil/filter changes every 1500 or so. Never flogged too hard. Treat them well and they hold up for a long time is all I can say.
 
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1 ring change needed before new pistons and rebore is mentioned in NOC Commando Service Notes, on my 2nd set of std rings, changed rings to cure smoke on driveside on acceleration.
 

maylar

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There's a whole lotta "it depends" in that. My brand new 850 needed valve guides at about 7000 miles. Soft cam was worn to shit in 30,000.
 

rvich

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From what I've read here over the years I'd say that by 20,000 most people are starting to see signs that they need to get in there for a look and a refresh. But the problem is that as an example 27,000 miles over 47 years is less than 600 miles per year. It becomes more about how it was stored than ridden. Any bike that is 47 years old that has been ridden often will have needed engine work a long time ago. If you bought the bike fairly recently it's hard to say whether somebody has been in there or not.
 
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I've had her since mid '78 and have put all except for...... if I recall correctly about 6500 miles. Outside of being cantankerous when cold, a bit of seepage near the tunnel, and a little oil consumption as its never completely hot with less than 30 miles per ride... I find no purpose to poking it with a stick by going into it... Oh, the nuts and screwheads on it had no marks except those put there by me.
I took an Avon off the front when It was bought and continued with the k81 on the back until it wore out, so it still had one original tire( and a sorry state it was in too). That was long ago, and no one has driven it other than me since. I also knew the first owner.
 
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I have close to 50,000 on the combat since the rebuild. Like stated how well is it maintained, how god of an air filter are you running?
 
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An everyday K&N which I've forced into a decent fit..... We're wandering somewhat I believe. Anyway it may be gleaned that reasonable care/maintenance gives rise to a lengthy engine life, so 20K and well over is possible unless there's failure.
 
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This 73 850 belongs to a friend of mine. He purchased it in 1974 with a few thousand miles on. Through the 70s and 80s it was his only vehicle, so he piled on the miles. In the 80s , he rebuilt the top end at about 65,000 miles.
That was it for engine /trans work until this spring when he did a full rebuild on the bike.
Mileage at time of the full rebuild was 128,000.
Hard to believe, I know, but he is a straight up guy and that is the mileage covered to date.
Glen
 

concours

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An everyday K&N which I've forced into a decent fit..... We're wandering somewhat I believe. Anyway it may be gleaned that reasonable care/maintenance gives rise to a lengthy engine life, so 20K and well over is possible unless there's failure.
"How good the air filter is" is absolutely relevant. Running NO air filter will deliver 10,000 miles. An effective filter will be evident on the FAR END.
 

ashman

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This 73 850 belongs to a friend of mine. He purchased it in 1974 with a few thousand miles on. Through the 70s and 80s it was his only vehicle, so he piled on the miles. In the 80s , he rebuilt the top end at about 65,000 miles.
That was it for engine /trans work until this spring when he did a full rebuild on the bike.
Mileage at time of the full rebuild was 128,000.
Hard to believe, I know, but he is a straight up guy and that is the mileage covered to date.
Glen
They will do it Glen as I have said many times over bought mine new in 76 last of the 74 in stock and it was my only transport for most of its life the motor was completely rebuilt in the early 80s when I converted it to the Featherbed frame and the motor built for it as well some Combat mods, the only time its been off the roads was for the conversion and rebuild and replace the crack crank cases, I have well over 160k miles on it and has only had one rebore in that time, the valve guides have been done 2x in its life only because the first time my head was done up the so called head expert stuffed it up and anytime I go inside I always replace the slipper bearings, the crank and rods is still on stock size, I am still running the original valves but the springs have been replaced back in the 80s, I am running flat top Hepilite pistons the head has been shaved and have lots of port work done, my crank has been balanced at 72% for the Featherbed frame, my gear box had the lay shaft bearing blew at 12k miles and most is still original inturnals except for kick start shaft, KS gear and 4x replace the KS pawl.
Keeping the maintenance up to the bike and they will go forever, run good oil as well I run STP with my motor oil and have done so since 1978 and run a Lochart oil cooler all year round even in winter, the motor still gets up to temp with the oil cooler and running the oil cooler and STP in my motor has given it very long life and because my Norton is my hotrod bike I ride it like a hotrod and I don't pussy foot it, with the Joe Hunt maggie it starts first kick every time with the folding T160 RGM kicker, I was running PWK carbies but at the moment am going back to my Amals which are still in good shape as they aren't the original Amals as they wore out before 1980, I miss the ticklers and always had float sticking problems with the PWKs.
But some Nortons seem to run forever as mine has and a lot seem to have very few miles on them for their age and lots of problems with them, for the last 7 years my Norton is semi retired but I still take it out, still ride it hard and still has plenty of get up and go and gives some modern riders a good scare, it has only let me down 3 times in over 46 years of ownership and 2x was from a broken chain, once doing a burn out in my younger hoon days and the other time when it threw the joining clip and the major one when the Boyar black box shit itself a week after the fire back in the 80s, but since 2013 I have owned 2 modern Triumph Thruxtons and now the 1200 Thruxton is my everyday rider.
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Ashley
 

RoadScholar

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All things being equal (maintenance, attention to detail, yada, yada) , consider where the Commando was designed, built and tested...

If you have to go riding when the ambient temperature is over 100 (F) which is not uncommon in the US desert states (Arizona, New Mexico, Texas, others) your Commando won't last long, get stuck in traffic, half that, start sporting, half that...

The Commando is at its' best on a twisty road when the ambient temperature is between mid 60s (F) and mid 70s (F). I'd bet that the Commando is happiest in the real English countryside; you Brits are some real lucky guys!

Best.
 

ashman

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In my state of Queensland its hot riding weather for 9 months of the year, above 30c to over 40c most of the time in summer, so riding a Norton in hot climate can happen if you run a oil cooler and good 50 grade oil and your motor will love you for it, our winter days are around 18c to 27c and just the start of Spring and we are already hitting 30c I have always had a oil cooler on all my older British bikes and have never had any problems riding in traffic and around the suburbs when hot, I know when I first bought my Norton new GTX was the reconmended running oil and it ran hot in traffic but after a 1 year I started running 50 racing Pennizoil with STP added and the oil cooler and had no more problems with running hot, I run the oil cooler even in winter and I have still got long life out of my motor, you just got to adjust to riding in hot climates, but the Norton does run better in the cooler winter months.

Ashley
 
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