New member questions.

New member with several questions.
I recently purchased a 1971 Norton Commando non running project that hasn’t run since 2003. While not a stranger to vintage bikes (I have a couple of Triumphs) this is my first Norton. I did the normal fluid changes and was able to get the bike running. The deeper I get into it, the more I find is either deteriorated or missing.
I know that I need new tires. There is a 3.50 19 on the front and a 4.00 19 on the rear. The Dunlop site recommends 4.10 19 front and rear K81. Is this correct/ advisable?
Also need a new drive chain. Recommendations as to replacement and number of links?
The horn doesn't work. What an ordeal removing that. I had to remove the oil tank and battery tray to access. What was the designer thinking? I couldn’t find a horn relay on the bike but the wiring diagram shows one. I’ve ordered a new horn but is the relay necessary? I didn’t mind removing the oil tank as I had planned flushing it out and replacing all the oil lines.
Speedometer doesn't work and has cracked lens. Any recommendations for repairs in the U.S?
Sorry for the lengthy post and thanks in advance for any guidance.

FL54 said:

There is a 3.50 19 on the front and a 4.00 19 on the rear. The Dunlop site recommends 4.10 19 front and rear K81. Is this correct/ advisable?

Click to expand...

For 1971-on 4.10 front and rear were specified.

FL54 said:

Also need a new drive chain. Recommendations as to replacement and number of links?

Click to expand...

Number of links will depend on the sprockets fitted (front).

FL54 said:

What an ordeal removing that. I had to remove the oil tank and battery tray to access. What was the designer thinking?

Click to expand...

Yes the joke is the horn was placed on the production line and the bike was built around it.

FL54 said:

I couldn’t find a horn relay on the bike but the wiring diagram shows one.

Click to expand...

I don't know which wiring diagram you have been looking at but there's no horn relay although it's often a good idea to fit one.

The only relays shown on the wiring diagram are for the Interpol alternating horns "Alternating horns circuit".

Welcome (no name given),

There is a 3.50 19 on the front and a 4.00 19 on the rear. The Dunlop site recommends 4.10 19 front and rear K81. Is this correct/ advisable?
A: there will likely be between 3 and 7 different answers, but yes, those will work fine. Everyone has their own preferences, mine is Avon Roadriders in 90 aspect front, 110 rear.

Also need a new drive chain. Recommendations as to replacement and number of links?
A: 5/8 x 3/8 100 links. I usually buy a longer chain in case of sprocket replacement.

The horn doesn't work. What an ordeal removing that. I had to remove the oil tank and battery tray to access. What was the designer thinking?
A: hee hee the age-old joke goes: How do you build a Commando? - Bolt the horn to the battery tray and install in the frame FIRST.


I couldn’t find a horn relay on the bike but the wiring diagram shows one. I’ve ordered a new horn but is the relay necessary?
A: not "necessary" but not using one could destroy your horn button internals over time.

Speedometer doesn't work and has cracked lens. Any recommendations for repairs in the U.S?
A: I always used Joel Levine near Atlanta, but I believe he retired.

HA! LAB jumped in just before me, while I was typing!

Welcome aboard the Norton Train!
I managed to get at the horn on my 74 850 by removing the rear wheel and mudguard. I replaced it with a Fiamm Freeway Blaster high note in the stock location and it is super loud even suv driving latte sipping types seem to respond to it. Once ihad the old horn off it sat in a box awaiting restoration until one day put a 13v battery to it and it worked fine. Issue was a poor battery on the bike when I first acquired it, so good toconfirm this and all connections before pulling off various bits.
Be sure to get workshop manual for your bike model/year...free to download in the technical section of this site. I also find the riders booklet helpful for basics like switch gear layouts and where to locate all the greasing points...note, the swingarm zerk fitting is for OIL, not grease...besure to confirm if a previous caretaker has put grease in swingarm...if so you will need to r&r the oillite bushings within.