RRussellTx - 1974 Commando 850 Project

Fast Eddie said:

According to your first post “It had some engine troubles in the 80's and has been in my Dad's garage ever since”… I’d suggest it’s worth stripping it for this reason alone.

Also, looking at your cars, you’re a guy who likes things done right, so stripping the motor seems a no brainer to me. The big ends could’ve been sat metal on metal for decades damaging the bearing material, the oil seals will likely be hardened, etc. Plus, you don’t know what shite is in there !

A Norton motor is SO simple to work on and there’s SO much advice available on what to do.

You’ve got the Norman White book already, now get yourself the Mick Hemmings engine and gearbox rebuild DVDs, and get stuck in, I really don’t think you’ll regret it.

But that said, if you don’t fancy doing it, perhaps drop Greg Marsh a PM…

https://www.accessnorton.com/members/marshg246.7855/

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Been meaning to post this.
Here's the link to the Hemmings DVD's. The engine, gear box and forks all apply to your ride.
Mick Hemmings is a Legendary Norton guru.
Who, unfortunately is no longer with us.

Free at last.
And so it begins.

As mentioned by everybody... You definitely want to spit the cases and look at everything. It can be intimidating the first time, but it is a simple engine. I did it with nothing but a Haynes manual in the 70's, but I was young and fearless then, and there weren't the resources there are today.

The members here won't steer you wrong on any version of a rebuild.

@RussellTx I will add my concurring advice to "just do it". You are already past the hardest part.

STICK TO THE BOOK, in the exact order that it is presented. Use highest precision measuring on the crank and rods, pay attention to the INSISTENCE of properly radiusing the journals, that's there the grenade pins are. New crank & rod bolt hardware.

If you have not yet corresponded with @marshg246 Greg, you might go ahead and make contact.

I forgot whether I mentioned it, but I have a 100-line spreadsheet framework to tick off component by component, you can download it from the "files" section, it's an Excel spreadsheet...

I put a laugh on it, because, let's see how far the build goes...
This stuff can be intoxicating and restraint is hard.

I will remind you on what your original goal was.
And, A well sorted 'Stock' Norton makes for a fine ride.
It's easy to get lost in the puffery.

That being said, something to consider is your breather.
You can leave it alone and add either the very nice NYC sump breather, or the Mike's XS650 line breather.
Or, since your splitting the cases, send them off to Matt and do the CNW mod.
Be very careful opening the CNW website. You'll find money flying out of your wallet.

Everyone has their favorite mods, Trying to maintain 'Stock' there are 3, I consider very worthwhile.
1. Breather mod of some kind.
2. 13mm master cylinder on front brake
3. Clutch rod seal.

Notice I didn't mention E ignition. Pick your own poison there.
I have run Boyer, Lucas Rita, Tri spark and Pazon Altair.
I'm not really convinced any are better than the original points.
Different, yes, better...... that's whole nother kettle that's discussed endlessly on the site.

Looking forward to your progress...

There is no real hurry is there? If you get bit by the need to go fast bug drive your blue car.
500 ft. lbs. of torque in a 2600 lb. automobile should do the trick...although it can be difficult keeping it on the road or from swapping ends on you. That's a boat-load of HP/Torque for such a light buggy.

Johnm and others are giving you their time offering some good guidance/suggestions as they did for me when I restored my project. This site is a gold mine of information, parts access, how-to, trouble shooting mystery issues etc.
Your bike has been sitting for 50 years, as did my 74', which was a barn find in Nevada with 1300 miles on it. No idea why it was in the barn but I went back to the bare frame, spent a year on a ground up and glad I did.
Have you dismantled the Amals yet?

If you want to have it perform as it was designed/intended keep dissecting and find all the unknown issues still hiding from you. Some unchecked part/component lets go at 70MPH you are going to wish you had looked a little bit deeper when you had it apart. I'll bet you already know internal engine failure can eat a lot of new goodies as well.

Its easy to read you are having fun with this project and your enthusiasm is admirable. Do it correctly now while you already have it apart. so you don't have to take it apart again (which you will) but...at least not right away.

Those cylinder walls, sleeving is a good option.

Schwany said:

Free at last.
And so it begins.

As mentioned by everybody... You definitely want to spit the cases and look at everything. It can be intimidating the first time, but it is a simple engine. I did it with nothing but a Haynes manual in the 70's, but I was young and fearless then, and there weren't the resources there are today.

The members here won't steer you wrong on any version of a rebuild.

Click to expand...

Split the cases. Spitting on them won't help. Oops

Deep breath...

Thanks for all the great feedback!

I have a couple of weeks moving kids into colleges amongst other tasks that will take me away from the garage.
I'll probably use that time to review the manuals, consolidate all of the suggestions, get the Hemmings DVD's and review them as well.

I'll check my confidence level after reviewing all of that!
Everyone knows I'm going to break everything down, I just need to talk myself into it.

When I get some time in the garage, I'm going to continue breaking everything down and bagging and tagging it.
I'll follow the book, but I'm going to leave the big chunks intact until I get time to work them one by one.
Namely the engine, gearbox, carbs, wheels and forks.
I'll split the cases, but it may be a while before I do.

I'm not fast, but I try to do a thorough job.

After I get everything apart, I think I'm going to start cleaning everything up to see what we have.
Then I can make decisions about direction (like painting the frame or not and those types of things).

You guys have been a great help!
I'll keep you posted as I go along.

Thanks again!

Take your time like you plan to do. I don't think you need lessons on building an engine if you built the engines for the Cobra and the Mustang. Lefty loosy righty tighty unless reverse threaded.

The easiest approach with a Norton engine is stock. And stock is plenty given how much traffic is out there today. The hot rod stuff is fiddly and nowhere near as easy or forgiving to install.

I'm guessing you might be in Texas based on your username. Here's some useless information of which I am full of. I was in Brownville TX for a week one summer. It was sort of like walking on the sun.

The standard 850 motor is just fine. the 'Mike's XS' reed valve breather is cheap and fit for purpose - just plugs into the breather pipe, and is a great way to keep your motor oil tight.
Which reminds me - the tach drive is a known leak point, and A-N sell one with a proper oil seal fitted. Not expensive either.
I'd also speculate that your cylinders will go to a +0.020" oversize with no dramas.

To contribute to the useless information theme; I watched a band (and drank beer) at the Flying Saucer in Fort Worth, and witnessed a Texas Flood in Greenville.
Definitely not something I've ever experienced in the UK!

Update,

I got most of a day in the garage and pulled quite a bit of it apart.
I'm stuck on a stuck fork...

I got one side up super easy. Just like the book said.
The other side however, is not budging at all. I was able to loosen the large chrome cap but the assembly won't slide up.
I even put a strap to try to pull it up but no movement at all.

Is this common? I would heat it up but I don't have a clue where it is stuck...

Push the lower leg up

Yep, I tried that.
I can't even twist the lower leg, much less push it up.

RussellTx said:

Yep, I tried that.
I can't even twist the lower leg, much less push it up.

Click to expand...

Did you remove the bolt from the bottom?

Well, no use wrestling with it on the bike. Release the fork tube from the yokes. Loosen lower yoke bolt and reinstall the fork cap half way threaded down so you can give it a sharp rap to drive the fork tube taper out of the upper yoke. This way you can mess with the single stuck fork slider, tube, and damper internals on a bench or in a vise

o0norton0o said:

Well, no use wrestling with it on the bike. Release the fork tube from the yokes. Loosen lower yoke bolt and reinstall the fork cap half way threaded down so you can give it a sharp rap to drive the fork tube taper out of the upper yoke. This way you can mess with the single stuck fork slider, tube, and damper internals on a bench or in a vise

Click to expand...

Roger that.

concours said:

Did you remove the bolt from the bottom?

Click to expand...

No, following the book and I think that comes later.
The first side came apart super easy without removing the lower bolt so I think I'm ok to do it later.

That said, I may try that once I get it off the bike.

The base bolt has to be removed for the damper cartridge to come out.... I just finished a 1 year project modifying showa dampers to fit norton fork tubes... so I've taken dampers out and put them in 10 times in the last 4 months to test different springs

Well, I broke it loose as suggested but I still need to get the fork cap off to pull the fork out.
Can't get the fork cap off unless I raise it up to get the other wrench on it like in my successful side image.

I"ll remove the lower bolt next...

RussellTx said:

Update,

I got most of a day in the garage and pulled quite a bit of it apart.
I'm stuck on a stuck fork...

I got one side up super easy. Just like the book said.
The other side however, is not budging at all. I was able to loosen the large chrome cap but the assembly won't slide up.
I even put a strap to try to pull it up but no movement at all.

Is this common? I would heat it up but I don't have a clue where it is stuck...

Successful side.jpeg

• RussellTx
• Aug 13, 2024

stuck side.jpeg

• RussellTx
• Aug 13, 2024

picked clean.jpeg

• RussellTx
• Aug 13, 2024

Click to expand...

It is stuck in the bottom yoke - common in that condition.

Allen out, favorite penetrant, big screwdriver in the bottom yoke slot, big hammer. You won't hurt anything, might raise a little metal on the top edge of the slot but that's easy to fix. Use the widest screwdriver you have. A wide chisel would be better but they are usually to thick to enter the slot and you must enter.

It will come loose.

Yoke = Triple Tree = Triple Clamp = ? the thing the fork tube is through on the bottom.

Then remember that the bottom yoke must come off first. You'll probably have to beat the stem upward to get it out of the bearings - use thick wood and a heavy hammer - it's a PITA if you damage those bottom threads and if you mushroom them you'll have to destroy the shaft to get it out.

Greg.... He knocked the fork tube free, but it won't slide out of the yokes because the fork cap nut won't travel downward past the top yoke..... And he hasn't taken the base bolt out of the fork slider so the damper assembly won't lift out of the fork tube either...

He doesn't see that the base bolt in the fork slider is holding the damper assembly from lifting out. So, instead he's trying to unthread the cap from the damper rod to take the fork tube to the bench for disassembly..