New project Introduction and questions

Allow me to introduce my new project. What I think is a 69 Commando 750. Correct me if I'm wrong please: VIN on bike and engine: 20M3S/132818.

I'm going to restore this thing. It has a lot of rust and missing/broken items so I began to tear it all the way down.

My first question is can I switch over to Superblend bearings? Found a lot of sludge in the oil and case. The ones I removed from the crank were really noisy and crusty. If so, are these the correct ones? I know to check crank end play. Bearings


Here is my link to my photo folder on DropBox. Hope it works.

Thanks and look forward to picking the brains on this forum.

Welcome and you are in the right place for advice and yes Superblend bearings, mine you that is just a name they are called, you need the bearing numbers, but a lot of suppliers around, nice project.

A minor point, but the timing side main bearing should have remained in the crankcase, not on the crankshaft. You should check that the the required interference fit still exists for the bearing in the crankcase.
Unless the engine is to be tuned and/or thrashed mercilessly at 7000+ the standard ball race timing side bearing is acceptable as is the standard main bearing on the drive side.

Can I ask what you mean by “check that the required interference fit still exists for the bearing in the crankcase” ?

When I split the halves the entire bearing came out from the drive side. It remained on the crankshaft.

On the timing side the outer ring stayed in the case and the roller cage with balls remained on the crankshaft. I have yet to remove the outer ring from the case. I hope I’m using the right wording.

You need a good puller to pull the bearing off the crank as not much to grip behind the bearing and heat the cases up to drop the bearing in the crank cases I normally do that when I have the new bearing so, heat, drop the old bearings and put the new bearings in at the same time while hot and let the cases cool down, I do my and other Norton case over my wok burner on my gas stove, perfect for dropping bearings out then flip the case over and drop the new bearing in then do the other side case.
A lot shim the new bearing on the crank but I find Nortons don't mind a bit of end play.

Yeah, I was able to pull the ones on the crank off rather easily using the puller. Just have an outer cage on the drive side case to remove. I’ll follow the heat method.

From my reading the FAG NJ306E should be the correct replacement, correct? How do I check if I need the CN or looser C3 type? No, this will not be a race bike.

rv1890 said:

Found a lot of sludge in the oil and case.

Click to expand...

Fit the later filter assembly.

The standard replacement bearing is C3.

Good idea to clean the crankshaft inside passages of sludge and deposits.
I have not taken an engine apart.. yet... so I don't know if this can be done without splitting the crank.
There was a recent thread on splitting the crank
Will you measure the crank wear to see if regrind for conrod oversize bearings is needed?
Do share your name if you wish!
Dennis

Welcome @rv1890 (whatever your real name is).

This thread ought to go in the "Norton Motorcycle Restorations" section (just sayin')

Thanks Dennis, yes I plan on measuring the crank to verify con rod bearing size. I also will separate the crank for cleaning since there was lots of sludge.

Also, I didn’t notice the “restoration” section of the forum. Do I need to move it myself or does an admin need to?

At the risk of telling you what you already know, the sites below have proved most useful for my ongoing commando restoration in the US.

Greg Marsh- Good selection of parts, quality and easy to order via email. Best prices in the US for Genuine Andover and most other brands. Great prices on Electronic Ignitions. I check here first for anything over $20.

Andover Norton- OEM, less than $800 comes in duty free, not sure about tariffs atm. Very fast shipping. Easy site to navigate.

RGM- UK based, but will ship to the US. By far the lowest prices on camshafts and some other pricy bits. Better selection than Andover.

British Wiring- "correct" wiring hardware and tools. I've had mediocre luck with their crimp on bullets breaking, so may suggest tracking down the brass version somewhere. The rest of their hardware is fine.

Cycle Terminal- Great wiring supplies if you don't care about using Lucas bullets. Also have crimpers for the ring and spade connectors BW sells, but doesn't have a crimper for.

British Fasteners- I've ordered from here, but honestly would not recommend. They messed up a hardware order and were completely unresponsive. If you need BSF or CEI hardware, order direct from the UK.

EVBC Ebay Store- Have had a lot of NOS Norton stuff recently at a good price. I think they purchased the inventory of an old Norton parts distributor.

SMM Motor Co- Also have an eBay store. Cheap pattern parts, good for basic stuff, hardware is sub par quality. No brand names, but lots will be EMGO which is pretty decent for headers, stanchions, etc.

Richter Machining- British specialist machine shop that will ship. Did a great job on my Triumph. Get parts in early because he's usually booked a few months out.

Feked.com- mostly pattern parts, I got some stainless rims from here, and they were good. I think Devon Rim Company is the actual manufacturer.

Amal carbs are all over the place if you need them. Anywhere from 600-850+. I got a set from Classic British Spares on sale last year.

Classic British Spares- Expensive Parts, very fast and responsive machine work. Will grind followers.

Eurotrash Jambalaya- Good selection of upgrades and Stainless bits, USA based.

Some more sites to check:

http://www.enginedynamics.com/ - EdCo Machine shop in Petaluma, CA. THE place to send cylinder heads. Fair prices, reasonably fast turnaround

https://britishfasteners.com - British Tools. Good source for Whitworth parts and Brit-spec taps &dies

rv1890 said:

Thanks Dennis, yes I plan on measuring the crank to verify con rod bearing size. I also will separate the crank for cleaning since there was lots of sludge.

Also, I didn’t notice the “restoration” section of the forum. Do I need to move it myself or does an admin need to?

Click to expand...

One of the admins already moved the thread!

Post lots of pix!

rv1890 said:

Allow me to introduce my new project. What I think is a 69 Commando 750. Correct me if I'm wrong please: VIN on bike and engine: 20M3S/132818.

I'm going to restore this thing. It has a lot of rust and missing/broken items so I began to tear it all the way down.

My first question is can I switch over to Superblend bearings? Found a lot of sludge in the oil and case. The ones I removed from the crank were really noisy and crusty. If so, are these the correct ones? I know to check crank end play. Bearings

Dropbox

www.dropbox.com

Here is my link to my photo folder on DropBox. Hope it works.

Thanks and look forward to picking the brains on this forum.

Click to expand...

I found the exact same bike same color 1970 commando and I think it was an S varient but pipes are missing. Cylinder was off and hidden in the guys garage along with the clutch. found some of the items. All torn down and cleaning, preping everything. trans case was out of spec. Loose bearings, but I found an Ebay case and it was a good one. Trans is now together and bench test good. much more to do. Keep with your project even if it takes forever. I think I will be sad when its done.

Got the crank separated. Cleaned out some sludge, but nothing too crazy. Journals look great. Just hit them with some polish.
The journals measure 1.739 and 1.744. The bearings I removed were stamped with 23255 lower and 25384 upper. The internet tells me that's standard size. With those journal measurements do I go undersized now? My initial guess is either .010 or .020, but not sure.

Crank Photo

Also got the cylinder torn apart.

Cylinder Photo

rv1890 said:

With those journal measurements do I go undersized now?

Click to expand...

You must have the crank reground to fit undersize bearing shells. 1.739"/1.744" would be below spec for standard shells (1.7509"/1.7504").

I was planning on getting new bearings. Just wasn’t sure if I needed 10 or 20.

I need to get the crank reground with those measurements?

The first regrind size is 1.745/1.7400 (-0.010") so you might have to go to second undersize 1.7305"/1.7300" (-0.020"). Note that it is important to keep the 0.090" radius see manual section C20.
https://www.classicbike.biz/Norton/Repair/70up_Commando/70upCommando.pdf

First, re-check your measurements. I find it odd that they are .005" different.

Yeah, I think you’re right. I will do that this afternoon.