Parts to replace during a complete engine teardown?

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Sep 9, 2008
My newly acquired '74 Roadster MkIIA shows 26,000+ miles on the odometer. I'm in the process of doing a complete engine rebuild, and was wondering which parts should be replaced automatically (for example, bushings, seals, bearings, valves, guides, springs, etc.). Rigor and mechanical excellence are paramount; cost is totally secondary.
Nah, too easy. Where's the fun in that? I want to sweat, suffer, and swear. :lol:

Oh, I forgot, my question also includes the gearbox.
Simple solution: crate up the engine and gearbox and ship them off to CNW for full rebuilds. That will cost a lot less than ordering a new engine from Norvil. You can spend the savings on a repaint and getting some nice new wheels built up, etc.

If you're into suffering, just remove the engine by yourself without assistance. Plenty of opportunity for sweating, swearing, and suffering! :p

I work on all my vehicles myself (3 bikes, 3 cars) simply because I insist on knowing exactly what was done and how it was done. No one else is going to put the same care and attention into the work as will the machine's owner. Therefore, the option of having somebody else--no matter how "qualified" or "experienced"--do my engine work does not exist for me. That's not to say I won't farm out certain critical machining operations that I don't have the capacity to perform myself, but I try to minimize such operations by purchasing the tools or machinery necessary to do it myself whenever feasible. I'll probably have way more invested into this bike than it's worth when I'm done, but I'm sure many of you can relate. Moreover, sometimes the journey is just as--if not more than--important than the destination.
Here is a third option. Find a good local machine shop. Disassemble each major component such as head, engine, gearbox one at a time.
Deliver to machine shop with your check book.
Frame off restoration? Find a good painter/powercoater.
Wheel condition will dictate whether to ship to Buchanan's
Replace all wiring and electrical parts.
Update with sensible upgrades? Belt drive? lighting? carbs? cam?disc brake?bearings?swingarm?final drive?
Throw away all of the hardware and replace.
Give your tanks, oil and gas a thorough review
Replace anything that even looks like rubber. tires,isolastics,etc.
Set aside a good year to complete.
Rely on this site and lots of manuals to complete.
Simple :roll:
Basic items:

Gasket set, complete
Oil seal set, (must be ordered individually, incl. intake guide seals)
Rod bearing shell set (undersize per your machinist's directions)
Rod bushings
Main bearings (F.A.G. "Superblend" or equivalent)
Transmission bearing set
Transmission bushing set
Cam bushings & thrust washers
Crankshaft shim stock (for end float)
Camchain adjuster rubbing block
Carb overhaul kits with viton-tipped float needles

Main wearing parts - You or your machinist must carefully verify condition and compare to wear tolerance specifications given in the shop manual (typical items shown in bold):

Pistons & rings
Valves, guides & springs
Clutch plates
Clutch actuator rod
Primary chain
Camshaft chain

Valve adjuster "tappet" screws
Cam followers (lifters)
Transmission gears & shafts
Kickstart gear pawl & spring
Everything else in the engine including pushrods, rockers & shafts, etc.

The list will never end until you cover every part. You need to use a litle common sense and scrutinize each part closely.
Great feedback from Grandpaul. When I pulled my last engine I realized all of the opportunities to inspect/fix/upgrade other things. You will want to look into the rear iso at least. It is a slow and usually rewarding process. You will also get to know your mail/fedex/ups person. I am now on a first name basis with all of them. Yes, you will never recover the cost but the final check rides are worth it.
Mike :wink:
Good comprehensive list from GP.

When I did mine, no machine work was needed - everything was still well within spec. Honed the cylinders with a coarse stone and lapped in the valves.

I replaced all bearings, rings, gaskets, bushings in engine and transmission, along with new MkIII isolastics.

I rebuilt the carbs, and everything looked good, but I couldn't get it to idle properly. I ended up springing for new Amals ($195 apiece), as the consensus was that the slides were too worn, leaning out the mixture.

About 1500 miles so far, and nothing has flown apart.

Check your rotor while you have everything apart. It seems the steel core has a tendency to separate from the main body, with potentially catastrophic results. Mine was loose (about 5 degrees of rotational play) so I sprung for the Wassel one.
I have all of the Mick Hemmings engine/gearbox rebuilding DVDs. He pretty much recommends replacing everything in the list that grandpaul graciously provided.

I'll farm out the frame to the powdercoaters and the wheels to the lacers, and I'm sure I'll end up replacing everything Isolastic.

I've just started rebuilding this thing, and I've already spent about $1,000 in replacement parts. A second mortgage might see me through to the end. :lol:
Nice job by Grandpaul. The last Norton engine that I rebuilt lasted over ten years and brought me cross country, and that is pretty much what I replaced. I did change the cam although it showed little wear because I though some were a bit soft from my vintage.
You can save enough on shipping by placing one or two big orders instead of multiple small orders, to pay for a significant part of that parts list. Just don't get anxious to do onsie-twosie stuff. Go through the process by reading the shop manual and studying the parts diagram, then checking what you've got. Some suppliers have free shipping on bigger orders, too. It all adds up.
Paul you nailed it, I thought I had all the parts needed a few times now only to find I needed a few more items. The shipping can add up real fast, But I must agree with you Huffer doing it yourself is so much more fun if you have the know how and tools, But some of these older bikes can present problems if you don't have the proper tools. I have seen things that make me cringe and I am sure it was due to the fact someone didn't know what tools were needed. So also look into getting them too and have yourself a ball, I know I am on my project. Now if my wife don't leave me cause of the money things should be ok!! LOL LOL Take care and ride safe, Chuck. :D :D
I intend to get (or already have) all the specialized Norton tools needed for the engine and gearbox. Will I amortize the cost of these tools over more Nortons after this one? Probably not. I'd like to restore a pre-1971 Bonnie next (if an unmolested example still exists), but I can see another Commando in my future eventually. When I leave this sodden earth for good, someone's going to get an awfully nice set of barely-used British Bike tools. :eek:
Perhaps the best thing to do is to become friendly with a group of owners within an hour or two's ride if that's possible. Someone will always have the gasket or shim that you need and swapping is always more enjoyable than buying !

After something like 25 years and 100,000 + miles on my Mk111, I realise that the cylinder head is original and so are the crankcases, but that's about it really. It all depends. If you find a crank like mine which was 20 thou higher on one journal than the other and a detacthed stellite follower foot then it doesn't leave much over.

:D Just had a thought - Rocker covers are OE too !
While you're in there, I'd upgrade to an automatic cam chain tensioner. Steve Maney has sourced a nicer crankshaft oil seal as well. Go ahead and spring for the Kibblewhite valves and valve guides while you're at it.

I don't think Keith Johnson at Johnson Cams is taking any work at the moment, but he does some of the best head-work in the business. If your cam doesn't meet spec, he also makes a nice streetable unit - the J360. It doesn't have a tach drive though, so you'd need to go electronic from there.
Say Dr_Hiller, where does one obtain said aftermarket parts? I think I'll stay with the stock cam, but I'd like to look into the tensioner, seal, and the valve stuff.
RMA Engineering, no web address, makes the cam chain tensioner. 408-578-4032 Some of the vendors may stock it. I got mine directly.

The Kibblewhite Black Diamond Valves and Ampco45 guides (they may do seats as well) are available through your regular Brit parts suppliers, Old Britts, BritCycle, Fair Spares should all have access to 'em.

Almost all of the vendors you could possibly need are listed in this document Resources Rev 03-22-08.pdf
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