What is a stock-ish Norton engine's life expectancy?

In stock form, with modern oil (I run 15W-40 Rotella diesel JASO2 stuff in all my bikes), what will these bikes do? 15K miles? I know I should mount an oil filter, but I haven't figured out a good placement and hose routing on my N15CS yet. I've been meticulous about draining and filtering my oil (due to sumping, eesh), or replacing it with fresh stuff, and the bike has never shown a hint of metallic crud in the sump since a full rebuild. In 1K miles it's had the break-in oil (Lucas), then fresh trusty Rotella or filtered through a coffee paper filter about every 100 miles LOL. No smoke, no issues whatsoever. I'm wondering how long the good times will last (cue the Kinks song, sort of). I may be lulled into feeling it's all good but am I sitting on a time bomb? My other bikes run the oil through the clutch and gearbox, but the Norton is just the engine, which has to help, right?

Back in the day, folks treated their bikes like race bikes… only had access to very basic oils… had limited mechanical knowledge or sympathy… and most likely ran things on a shoe string budget.

So, perhaps high mileages weren’t the norm !

Today however, all of the above is pretty much reversed, you most likely ride very modestly, use great oil, change it frequently, buy the best parts, etc, etc.

So, provided it was rebuilt well, I’d say you should expect MUCH higher mileage than that, 3-4 times more in fact. Perhaps more?

Regarding the oil filter… modern oils have high detergent content, this is designed to keep crud in suspense in the oil, in order for the filter to catch it. Old oils didn’t have detergent and hence sludge traps were relied on to catch crud.

So… a filter really is a good idea seeing as you’re using modern oils.

Jim Comstock recommended these smaller in line oil filters a while back, you might be able to squeeze one in somewhere, note they’re disposable, not serviceable.

gpzkat said:

In stock form, with modern oil (I run 15W-40 Rotella diesel JASO2 stuff in all my bikes), what will these bikes do? 15K miles? I know I should mount an oil filter, but I haven't figured out a good placement and hose routing on my N15CS yet. I've been meticulous about draining and filtering my oil (due to sumping, eesh), or replacing it with fresh stuff, and the bike has never shown a hint of metallic crud in the sump since a full rebuild. In 1K miles it's had the break-in oil (Lucas), then fresh trusty Rotella or filtered through a coffee paper filter about every 100 miles LOL. No smoke, no issues whatsoever. I'm wondering how long the good times will last (cue the Kinks song, sort of). I may be lulled into feeling it's all good but am I sitting on a time bomb? My other bikes run the oil through the clutch and gearbox, but the Norton is just the engine, which has to help, right?

Click to expand...

Are we on the launch pad to an oil thread?

The Norton engine should last a long time if you aren't hitting the rev limiter every shift. Just check your fasteners and change oil often. Stock is much friendlier on the clutch and gearbox as well. Don't run the primary or rear chains tight. The engine may get noisier with time and milage, but the noise never kept mine from running. I may be the only person visiting this site that has a Norton engine that gets noisier with time though. 15K miles is not even close to the end of a Norton engine owned by a meticulous restorer like yourself.

I've changed my spin on oil filter hose routing 3 times. The routing doesn't make any difference other than aesthetically. Oil still gets where it needs to go.

A good small inline filter on the return or feed line would definitely look better than my mess. I don't have a center stand so a small spin-on filter was easy to mount behind the gearbox.

My 850 is still on original main bearings and big end bearings, pistons are original but it's on second set of rings as the first set started smoking on acceleration. A light hone and new rings cured the smoke. Its also on its second speedo so mileage is unknown.

Would something like this work https://www.mapcycle.com/categories...p6510-map-universal-oil-filter-kit-black.html You could get smaller P clamps to one of the kinda vertical tubes your frame and another one of the same size included with the kit to help hold it in place.

As Nigel suggested, you can add a transmission filter to your bike's oil return line. I have a 70 commando which didn't have an oil filter from the factory like later models did, so I added the transmission filter to the return line from the oil pump. The filter catches all particles down to 35 microns (.0013") and has a powerful magnet that can remove ferrous metal particles down to 3 microns. It also have a bypass valve that keeps a clogged filter from blocking the return line... Here's a link to the thread I posted on my own installation....

Thanks all. I gotta get off of my butt and put one of those filters in. I have been in constant motion on vehicles lately, painting, fixing, buying, selling, ugh. The bike has been very good, it just runs and runs, and doesn't do any 'bad stuff' since the full rebuild (like blowing smoke, exploding, etc). Worth a bit more investment to protect its bitchen' ness.

My oil feed lines are 1/2" not 3/8". I see they make a metal one with 1/2" Space is very tight on my bike. I have a single VM34 Mikuni and it has 1" of space behind it where I run a foam filter, contorted terribly, but working effectively. Maybe I can finagle something into the space underneath, but I was also hoping to devise a 90 degree fitting to route the air intake downard for more air filter room. Such is the life of a modified hybrid owner, always coming up against some hurdle or another.

I’d be looking under, or possibly behind the gearbox, especially if a pre formed hose with a nice tight 90 degree bend could be used…

Or am I way off here ?

Fast Eddie said:

I’d be looking under, or possibly behind the gearbox, especially if a pre formed hose with a nice tight 90 degree bend could be used…

Or am I way off here ?

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That could work. My son borrowed the bike and then took off for NZ and Australia, so I'll head over to his place on Friday when he returns and get my bike back, have a good look. I'd like it to be easily removed/refitted.

I have a std Norton oil filter on my N15 for ages. It sits vertically in front of the rear tyre. There is an unused frame lug. You just have to make a support for the filter. I am on the road now and can't post pics. (maybe a drawing..)
If the camshaft hold up, a well assembled engine should be good for 80 000 km or more.

Fast Eddie said:

Back in the day, folks treated their bikes like race bikes… only had access to very basic oils… had limited mechanical knowledge or sympathy… and most likely ran things on a shoe string budget.

So, perhaps high mileages weren’t the norm !

Today however, all of the above is pretty much reversed, you most likely ride very modestly, use great oil, change it frequently, buy the best parts, etc, etc.

So, provided it was rebuilt well, I’d say you should expect MUCH higher mileage than that, 3-4 times more in fact. Perhaps more?

Regarding the oil filter… modern oils have high detergent content, this is designed to keep crud in suspense in the oil, in order for the filter to catch it. Old oils didn’t have detergent and hence sludge traps were relied on to catch crud.

So… a filter really is a good idea seeing as you’re using modern oils.

Jim Comstock recommended these smaller in line oil filters a while back, you might be able to squeeze one in somewhere, note they’re disposable, not serviceable.

Click to expand...

Good points, but if I may offer a (non Norton) data point....
My bevel Ducati has no oil filter, only a tea strainer thing, which I suppose is quite good at stopping lumps of clutch lining, but definitely does not do much for catching metal bits. There's a sludge trap in the crank though.
I've not been doing a lot of milage on it for quite sometime, but it's definitely done over 30 000 km since the last time I stripped it. Oil, all 5l of it does get changed regularly, around every 1000 km, and it does stand still over winter. I've never used non-detergent oils, usually a semi-synthetic multigrade.

When I stripped it, I was expecting to find quite a lot of sludge and gunk hiding in the corners, but it was actually very clean. I was going to get the main bearings changed anyway so I removed the sludge trap plugs, and was quite pleasantly surprised to find the sludge trap less then half filled.

I would really like to fit an oil filter to the engine, but with all internal oil ways, this requires some quite tricky machining since Ducati use a steel tube cast into the crankcases with very little metal surrounding it to tap into. My conclusion was that I'm going to be long gone before I manage to wear out this engine, so no changes made.