Britbike forum Forums British motorcycles in general British motorcycles in general What was the LIFE expectancy for Britbike motors?

While watching the recent oil filter thread, I got to wondering how long those bikes were expected to last.
In some ways, like American cars in the ‘50 - ‘60s, you’d think the factories were planning on replacing them every 3 -5 years. Good plan for repeat sales revenue. On the other hand, folks using the bikes in England to get to work needing reliable machines, not just for frivolous recreation, would not want that expected replacement expense!
The oils available back then didn’t have the detergents in them, and without a filter in the design, the bearings were destained for failure just a matter of time, somewhat controlled by how often the owner spent money on oil changes. Maybe not that often. The sludge trap design also used on aircraft engines at that time is a good example of expected heavy maintenance work. Aircraft engines Had/Have a “Time Based Overhaul”, based on flight hours time in service. At TBO, take the whole engine apart, which would certainly give access to the crank throws and the sludge traps. A week-end sludge trap cleaning was not likely and the bikes were not regulated for any required maintenance, the owners had the Out of sight… Out of mind mentality. Most likely the only time a sludge trap was accessed (and maybe not even then cleaned!) was OC, which is On Condition. In the aircraft maintenance trade that means, for cause, like a failure, like a rod through the case! The traps I have cleaned are just packed with rock hard accumulated gunk, baked on in a small place!
So after my rambling on, I do know the bikes DID last quite long in many cases. A tribute to the ability of the motor to keep running as it was slowly wearing. Maybe the life expectancy wasn’t even in the decision to purchase! They just looked good!

...to add:many NEW (now) mid sized bikes like Husqvarna, KTM; Kawasaki; etc are in the need to dismantle a lot on the top end (and many more things to reach there) to ONLY adjust the valves and the adjust is more complicated than these other old bikes.
And bear in mind that now most of the bikes are not used to go to work (except small cc ones) so you need to perform a major task or the engine will perform poorer and poorer...
Possibly on big bikes too but people trash it or sell it before something happening. Even more in places like USA where motorcycles (and vehicles in general) are cheap
The consumers now do not want to wrench (plus the scanner problem that only the dealers have the software) so are not appliances like they try to sell.
Seems not so much have changed

20,000 miles was supposed to merit a full overhaul.

In my early days with bikes (in UK in the 1960s) most bikes were used for personal transportation--most typically to go to work and back 5 or 6 days a week.
Every 2-3 months the bike would be given a "service" which involved a decoke and an oil change as well as resetting the points gap and greasing through whatever grease nipples were fitted.
The decoke involved removing the head and getting the carbon off the tops of the pistons and the cylinder head/valves etc.
There were few battery problems as most bikes were fitted with magnetos and the lights worked when the engine was running.
If there were more major problems you could go to the dealer although most guys would take the bike to one of the small back street repair shops who offered a quick turnaround and low prices.
I lived near to the Triumph factory and parts were always available very cheaply-- most of them came over the factory wall!
How long were they designed to last?
Theoretically the factory was happy to just get through the warranty period.
However in those days there were not the tools available to the designers that are available now--- no finite element analysis, no fatigof life prediction programmes etc so designs were generally over engineered.
Which I guess is why so many have lasted to this day.
And think about it-- you can take today a totally seized motor aged over 50 years and with a modicum of expense get it running again and use it on a pretty reliable basis.
The proof is that many of us do just that!
Just my two cents worth of course!

I remember direct lighting on all mopeds and some scooters and some two-stroke lightweights.

Not so common on “substantial” bikes. A magneto was often combined with (or even clamped to) a dynamo, which charged the battery through a control box.

Yes, TT, certainly a magneto for ignition and a dynamo for lights.
As standard the dynamo charged the battery but if you had a U/S battery or none at all then the dynamo ran the lights.
But only when the engine was running quite quickly.
But that was OK as at that age we all rode like Joe F**k.

I really have no idea how long these bikes can last, I suppose as long as we can get replacement parts and find people to weld up cases which had a rod put through them.
I rarely trust claims of extremely high mileage, as the instruments usually crap out long before they can register that many miles.
It's like the claims of getting 60mpg from a triple, best taken with a big chunk of salt.
Life expectancy from the manufacturer? Just past the warranty, and BSA overestimated.

We had a surprising number of 1920s and 1930s BSAs on our runs (100km Friday, 160 km Saturday) for last weekend's BSA National rally, so they will keep on keeping on. Parts can be quite hard to find, so a lot need to be made.

Pre detergent oil - 1960 . a annual de - coke was the usual procedure .

Turners siad to say 20.000 miles between major ovehauls .
He was right . 25.000 miles , everyday transport , tuned
progressively , occasionally reving the thing beyond belief ,
a 60 T 120 ran 25000 . But It'd alredy run 118.000 .

Seen reports on well maintained and less ferociously thrashed machines ,
a 61 Bonnie , t-150 , & Commando running 100.000 on original bottom ends
and bores . With good filtration & regular oil changes . 2000 to 2500 miles .

BUT Modern Oils Now are way better .Most Faults are ignorance & inadequate equipment induced .
they also require 'aircraft standard 'assembly , if you want the to fly .

The question was, how long were the motors EXPECTED to last. For British unit twins, 20K miles between overhauls was considered normal or acceptable, maybe a bit more for Nortons. People generally expected more for Harleys, maybe 40-50K, and BMW twins were expected to last 100K miles or more without an overhaul.

You have to remember the expectations of the new owners.
When motorways were introduced in the late 50’s loads of vehicles blew up on the high speed roads because they just weren’t up to it.

All my mates had 20 year old cars as learners. Problems were frequent. My current car is 21 years old and drives like new (sort of)

However an old vehicle is infinitely fixable by an enthusiast, new vehicles are dependant on more specialist parts.
Plus many old Brit bikes only made it to 40/60 because they broke down and spent a decade or two in a shed

GM did some research on oil filters in the early 1960s.
They found if the oil was filtered down to 4 microns, an engine could do approx 400,000 miles - highway use.
(and had good air filtration.)
Most early oil filters would be lucky to filter down to 30 microns.
May not be much different even today.

And, the SAE (Society of Automotive Engineers) took some late 1950s cars off the showroom floor,
ran them in as recommended, for quite some miles - and then ran them on a dyno flat chat.
They reported that they lasted an average of 7 minutes. For all sorts of reasons.
The oiling system was mainly the culprit - couldn't supply a constant flow of oil at pressure.
Cooling was also another.
Conclusion - don't expect to race an old style engine in stock configuration.

The British Army well prior to WW2 started insisting that the motorcycles they bought MUST last a minimum of 10,000 miles.
And instituted a testing program.
No one could meet that standard !!

BSA (the biggest) started a big research program into metals for cylinder walls.
All sorts of improvements were also needed - valves, big ends, piston alloys, steels, greases, etc etc
Air filtering in dusty regions.
The suppliers also HAD to produce a comprehensive spares book, so only like parts were substituted.

The local bike wrecker here commented that many bikes they get in for wrecking these days show signs that
the oil was completely gone out of many engines. So inadequate maintenance was/is a big factor even for modern stuff ...

P.S. And Lucas recommended that magnetos in particular got a YEARLY overhaul by your local Lucas Service Depot.
How does your maggie measure up !!

My, how things have improved over the decades.

It has long been my thought that modern engines last longer because of better metals and better oils.
Rohan's posting is more evidence of it.

Back in the 1950s,travelling salesmen usually bought Oldsmobiles and Cadillacs because those were the only cars that would go 90,000 miles without needing an overhaul. Today, with scheduled oil changes 150,000 to 200,000 miles is almost the "norm."

When I was running deliveries I bought used Chevy and GMC pickup trucks and suburbans, usually with 100,000 or more miles on them.
After an engine flush and tune-up, I put them back on the road. At 3,000 miles per month the vehicle would always get an oil change and a new filter.
I ran some of these trucks another 200,00 to 250,000 miles. At 300,000 to 350,000 total miles they were "tired," but still running.

By then the bodies were so weak from rust it was time to scrap them. But the engines were still running well.

drove my 1988 isuzu trooper 275k and it was still doing good when i sold it

Of course, our air-cooled engines don't last nearly as long as fluid-cooled.
In the way of a more appropriate comparison, our old Volkswagen engines needed a valve job at around 30,000 miles and a rebuild (more often replacement with a 'new rebuilt' engine) at maybe a bit over 100,000. They also featured nothing but a sump screen for oil filtration. However, they were low compression and not highly stressed engines, rarely spun at over 4500 RPM.
By comparison, my 21 year old Toyota, with 150,000 miles on it has only needed to have the oxygen sensors replaced and regular oil changes.

I'm not so sure that is strictly true ?
A quick warmup is what aircooled engines are famed for.

My father always quoted that he and a friend of his bought the same model of vehicle, just post WW2.
The friend literally only used it on Sundays on the run to church. Not a very long trip, so it barely got warm.
My father used his for a postal delivery run - so got a good workout, every weekday.
After 3 or 4 years, the well used one was still running well. The little used one needed new rings - it smoked.
These were liquid cooled, of course.

As any taxi or truck or courier driver will tell you, if it never cools down it will never wear out ...

???

Our '03 Expedition has 275K and is still very usable. Always starts, AC & heater still working and the factory paint is still good. Amazing. Our 22 year old F250 Power Stroke is at 310K and still going strong. Modern vehicles really do last.

Also, length of service in or before ET's time [or Page or Hopwood etc] was considerably different to the same motorcycle today.
Then.... the bikes were used with softer cams, lower comp pistons and more as all day plonkers. Albeit on worse roads and conditions.
In todays traffic - even with better bearings, proper oil filters, and better metals [blends and purity] for rings, guides and valves - the same bike is being asked to do 70mph for hours at a time on a freeway, accelerate harder between lights just keeping up with traffic, and work through the gears more cos there is more traffic and way more traffic lights etc. All this while manufacturers endeavoured to squeeze even more out of the lemon with performance cams, higher comp pistons and larger valves with shorter guides. And we haven't even mentioned leaded vs unleaded!

So IMO service life is subjective, it depends on the environment and the type of use of the motorcycle.

The Power Stroke is a Diesel. Those engines do millions of miles with proper care.
My '97 E150 with the 5.4L engine needs something every time I turn around. Good thing I only drive it to rallies, if I drove it every day it would have died by now.
I do know that the engine in the band bus I drive needed replacement at a little over 200K miles. That's an E450 with the big 7L 10 cylinder, cost about 10K for a new engine installed.

For what it's worth, I have been buying Brit projects for 40 years. I bought a Norton project last month. The odometers usually read in the low teens. The Norton's odo reads around 18K, which I think is the highest I can recall in my fleet of non-runners.

To me in the US, this represents the amount of use the bike got before something expensive broke that the 2nd, 3rd or 4th owner could not afford to deal with, or just cut his losses and pushed it out of sight.

It could be the clutch failed, the harness melted, the valves started leaking or the kick start broke something in the gearbox. All of these were the obvious problems that brought the bikes I purchased to a halt.

I don't know how that compares in Britain, where daily use was perhaps expected. Certainly not the case for most in America.

In 1950s America, most bikes were used for "sport," or toys, or summer short-distance transportation. The big Harleys and Indians were the bikes that some owners used as their ONLY transportation all year 'round.

British bikes were the only alternatives to those Harleys and Indians, and, if they were ridden and maintained PROPERLY (routine oil changes) would last those 20,000 miles before an overhaul was needed.

The problem was: Many American riders abused those bikes, riding them harder and at higher speeds than they were designed for,, and as a result, mechanical failures happened. Also, wiring problems such as insulation melts fires, and burned-out components, happened because American owners didn't read instruction manuals to learn that British electrics used a POSITIVE GROUND system. (I did several re-wiring jobs for customers because of this.)

I have seen a properly maintained '67 TR6R Triumph go 60,000 miles without an overhaul. A friend has it, and still rides it occasionally.
But he never abused it and used top quality oil, changing it every 1,000 miles.

+ 1,……….. And the U.S. Kept demanding the factory Hot Rod the motor, so they DID, at the expense of the previous design. They sold, but suffered the consequences!

That's pretty much the story of 1965 to 1972 BSA A65 twins.
The lower end oiling bushing system wasn't up to using 9.5 to 1 and even higher compression pistons.

Yup, bikes are for sport....I wear them out but never broke anything drag racing on the street or strip...New guides at 15,000 miles, and usually ringsand often a rebore...
....When its worn, just rebuild it...I desire no badge for maximising engine life ......

I remember reading an account many years ago of two Triumph twins being compared for longevity. Both were ridden daily but the difference was that one was ridden a short distance to and from and the second was ridden much farther to and from every day. The one ridden the short distance daily was in need of attention at a relatively low mileage ( can't remember the miles ) but the one ridden daily long distances was still running at 80,000 miles. I believe this was in England.

When I purchased my '67 Daytona engined bike in about '93, I pulled the head and noted it had been bored to plus 20 fairly recently so lapped in the valves and replaced the springs, replaced the broken intermediate timing pinion spindle and timing cover ( engine had been in a crash ), replaced the clutch plates and rode it well over 30,000 miles before taking the engine apart for the first time to " overhaul " it. It was ridden in a variety of trips, many of them quite a few miles and at cruising speeds of up to 75 miles per hour, often two up with luggage. About the only thing wrong when stripped down was that the exhaust camshaft right lump was badly worn and the follower was not even close to being the right one ( so someone had been into it and put in dodgy bits ) and in poor shape and one piston had nipped up due, I'm sure, to the fact that I had once overgeared the whole plot for a bit to keep the revs down ( 4.8:1 ) and on a trip into Alberta had experienced some seizure climbing a long grade in the mountains in about 100 degreesF riding with my buddy on his Harley. there wasn't much else wrong with the engine but I did the whole thing including the sludge trap just because I thought it was time. So mostly longish rides on an unknown condition engine and oil changes every 1000 miles on points and one 930 carb with filter so I guess I was lucky but not too shabby.

Agree with newer cars....we drive an '05 Grand Caravan and an '02 Mazda Protege and nothing but brakes, tires the odd battery and regular servicing....so far.

Cheers, Wilf