Newbie in for advice!

Since I'm new to classic biking, I have to ask you some stupid questions!
How can I tell if the compression is good?
I guess I should ask the owner why the cylinders are black, when they should be silver on a '73!

Some weaknesses known to only affect '73s? (as opposed to '74 or '75, I mean!)

cappo said:

Since I'm new to classic biking, I have to ask you some stupid questions!
How can I tell if the compression is good?

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A compression tester is a tool that every mechanic should have. Maybe you could borrow one.

I guess I should ask the owner why the cylinders are black, when they should be silver on a '73!

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Painting them black is a very common thing. Some people just like the look.

Some weaknesses known to only affect '73s? (as opposed to '74 or '75, I mean!)

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Not really.

cappo said:

How can I tell if the compression is good?

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Assuming you don't have a compression tester. If you operate the kickstart lever through its swing then you should notice the effort required will (or at least should) periodically increase significantly as one of the two pistons is pushed through its 'compression' stroke, unfortunately, this is where some experience would be useful.
Maybe have a go at kickstarting, you will soon get to know if the compression is reasonably good. :wink:

cappo said:

I guess I should ask the owner why the cylinders are black, when they should be silver on a '73!

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After 40+ years I wouldn't be too concerned about it. Black tends to be more durable so is often preferred by owners.

cappo said:

Some weaknesses known to only affect '73s? (as opposed to '74 or '75, I mean!)

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There's little difference between the '73 and '74 850 models.

The '75 (Mk3) is a slightly different animal so has its own strengths and weaknesses.

To get an idea of how certain years should look you can find that info here http://www.classicbike.biz/Norton/Broch ... chures.htm. Although it sounds like you would be acceptable to a mixture which are easier to find. Paint, seats and easily replaceable parts may be mixed around through the years and are an easy thing to change for various reasons. Myself I preferred to make my 60/70 S type as close to factory look as I could, but if I designed my own Norton it would be an early fastback with disk brakes and upswept pipes, unlike the original cigars and drum brakes. Like I said, nearly any bike in good condition can be made to run reliably if it isn't already. You'll eventually find one and it may be better to look for a while to get a feeling for what's out there and also get some feeling of how they should look/work.

So guys, I went and had a look.
I didn't have the compression tool, so I payed attention at the kickstarting procedure and it revealed what you told me L.A.B., you can feel the compression going up in the two chambers through the lever.
It's not pristine, it has some rust to it, a nick on the tank (there is what looks like blue paint under the black one...).
The steering lock is missing.
The owner showed me the separate oil tank, the cap (or the pipe next to it) is not properly sealed and the whole tank is wet with oil.
He says it needs some new gaskets there.
The engine was not cleaned before inspection and didn't show any oil leaks after it run for a while.
It started easily when cold, the kickstarter needing my whole weight (63kg) and some energy added to it.
There is no choke on the bike, but the original amals are there.
Frame, engine and gearbox numbers match.
I needed to hold the throttle a bit open for it not to stall, even as it was getting warm... The owner said it stalls if left to itself at idle, even when warm.
The gearbox worked pretty well (on the central stand, since the bike is not registered I couldn't take it for a ride).
I had the feeling fourth gear had some noise to it when releasing the clutch (very heavy!), like it wasn't engaged properly and the gears were slowly grinding (like when shifting on a car not properly depressing the clutch pedal) but it could have been something else.

I tried to stay composed and keep a "professional" attitude, but I just fell in love with it! That sound, those exhausts, that tank... Damn man!

cappo said:

So guys, I went and had a look.
The owner showed me the separate oil tank, the cap (or the pipe next to it) is not properly sealed and the whole tank is wet with oil.
He says it needs some new gaskets there.

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I heard these tanks sometimes have a crack, hope it is not in this case.
There is only a gasket in the tank cap, the hoses are fixed with hose clips .

The tank is steel or fibreglass?

Don´t you need indicators/blinkers?

rivera said:

cappo said:

So guys, I went and had a look.
The owner showed me the separate oil tank, the cap (or the pipe next to it) is not properly sealed and the whole tank is wet with oil.
He says it needs some new gaskets there.

Click to expand...

I heard these tanks sometimes have a crack, hope it is not in this case.
There is only a gasket in the tank cap, the hoses are fixed with hose clips .

The tank is steel or fibreglass?

Don´t you need indicators/blinkers?

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Looking at the damage on the tank, I think it is steel.

You can see the damage on this picture, right next to the Norton sign:



I couldn't really tell if the oil tank is broken, it's kind of tight around it!
I'd gladly get indicators, but they are not compulsory in Switzerland for old motorbikes!

Yes, that tank is steel, and appears to have blue at some point in the past.

cappo said:

Looking at the damage on the tank, I think it is steel.
You can see the damage on this picture, right next to the Norton sign:

I couldn't really tell if the oil tank is broken, it's kind of tight around it!
I'd gladly get indicators, but they are not compulsory in Switzerland for old motorbikes!

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A good paint shop can make a spot repair, I guess.

I have surplus Lucas indicators.
If you buy the bike and need some, contact me via PN.

Well, if I buy this one I'll have some stuff to sort...
- the damage on the petrol tank,
- the weeping oil tank (let's hope it's not cracked, 'cause I read it's pretty expensive!),
- the rotating peg on the kickstarter lever moves freely about,
- the missing steering lock,
- the incapability of idling even when warm (what could the culprit of that be?),
- the speedo shows some inconsistencies, the owner says it's the cable...

I guess this is what I should expect from a 40 years old unrestored example, isn't it?

cappo said:

Well, if I buy this one I'll have some stuff to sort...
- the damage on the petrol tank,

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That could be repaired without a complete repaint.

cappo said:

- the weeping oil tank (let's hope it's not cracked, 'cause I read it's pretty expensive!),

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It doesn't necessarily have to be expensive, but costs tend to rise dramatically when you pay others to do work for you.

cappo said:

I guess this is what I should expect from a 40 years old unrestored example, isn't it?

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Yes, all relatively minor things although you will almost certainly come across a few more faults as you go along.

Personally, I would be slightly more concerned about the apparent gearbox noise.

Thanks L.A.B., your posts are always enlightening!

I had a look at some online shops, the oil tanks I found were priced at 300 GBP+VAT and shipping... Just for the part!

As I tested the gearbox (as I said, on the central stand, letting the rear wheel spin freely), I kept looking at the gear indicator.
Its arrow was very precise, until I got to the fourth gear, where it overshot a bit.
The arrow wasn't lying on the number 4 itself, it went about one mm futher.
I was under the impression, I didn't engage fourth properly, or maybe I used too much strenght.
Nevertheless I tried to let the clutch engage, and it sounded weird.
I can't say if fourth gear was engaged, since the rear wheel was already spinning very fast I wouldn't have noticed the loss of pull.
And I can't be sure it was the gearbox either, since I don't know all the noises a commando engine is supposed to make.
Maybe something was vibrating and it resonated!
I pulled the clutch once again and went back to third. Then I tried to shift to fourth a second time,

Is it normal for the gear indicator not to lay precisely on the gear number? (It only happened in fourth gear)

I guess this is what I should expect from a 40 years old unrestored example, isn't it?
Actually, its only a small sample of what to expect. You will likely be fiddling with the forks, brakes, steering and wheel bearings, clutch, possibly the layshaft bearing in the gearbox, tuning or replacing the carbs, timing, wiring, maybe some top-end engine work, and rear shocks, among others.
I bought a 74 in similar condition (actually much worse) and have had nothing but pleasure getting it back to good-running and roadworthy shape. There was certainly much frustration along the way, but the payoff is very rewarding.
If you are in love already, what's a little effort? IMO, if the price is right, it's pretty much all there, and it's not already blowing a lot of smoke, it's well worth going for.
eBAy has oil tanks come up often, and I had mine repaired for $75.
And as for the pointer not precisely at 4 on the indicator, I think it's a non-issue. Personally, I wd never try to get in fourth (or even second) on the center stand with the motor running.

cappo said:

I had a look at some online shops, the oil tanks I found were priced at 300 GBP+VAT and shipping... Just for the part!

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The oil tank is usually repairable, probably no need to buy a new one.

cappo said:

As I tested the gearbox (as I said, on the central stand, letting the rear wheel spin freely), I kept looking at the gear indicator.
Its arrow was very precise, until I got to the fourth gear, where it overshot a bit.
The arrow wasn't lying on the number 4 itself, it went about one mm futher.
I was under the impression, I didn't engage fourth properly, or maybe I used too much strenght.
Nevertheless I tried to let the clutch engage, and it sounded weird.
I can't say if fourth gear was engaged, since the rear wheel was already spinning very fast I wouldn't have noticed the loss of pull.
And I can't be sure it was the gearbox either, since I don't know all the noises a commando engine is supposed to make.
Maybe something was vibrating and it resonated!
I pulled the clutch once again and went back to third. Then I tried to shift to fourth a second time,

Is it normal for the gear indicator not to lay precisely on the gear number? (It only happened in fourth gear)

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Difficult to say, it's something that might need looking at, but wouldn't necessarily be a reason to walk away from the deal, and in any case, the layshaft drive-side bearing really should be inspected and replaced if it's found to be a standard 6203 brass or steel cage ball bearing.