RRussellTx - 1974 Commando 850 Project

MichaelB said:

Grer Marsh has good pricing on Tri Spark, he has wiring harness info on his website.
He may build a harness for you also.

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Thanks!
I’ll be reaching out to Greg as my first stop once I get my parts list organized.

I picked up the parts from the Powder Coater and I think they did a really good job!
We will see once it goes together, but I'm happy for now.

Also, I talked to Greg and he straightened me out on sequencing and recommended cNw to do the breather mod and clean up some of the parts.
What recommendations do you guys have for what to send to cNw to clean up or modify?
I can polish parts on my buffer wheel but I can't do the blasting finishes.
Again, I'm not looking for a high performance machine but I would like a very clean, reliable and original-ish bike.

RussellTx said:

Also, I talked to Greg and he straightened me out on sequencing and recommended cNw to do the breather mod and clean up some of the parts.
What recommendations do you guys have for what to send to cNw to clean up or modify?

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I do my own "make new looking" but you can send all needing it to cNw. For non-72/73 750s I send the crankcases for the cNw breather if the engine is apart and have them do the cleanup. If you can't do them yourself and want new looking, send the empty: crankcases, gearbox shell, gearbox inner cover, and head.

While you're at it, send the oil tank (does not need to be clean). They come back completely clean, leak free, rear mount doubled, bottom mount removed and the bottom doubled to prevent future leaks, and powder coated.

If you are looking to have machine work done, such as cylinders bored, new valve guides and seats and crank ground, I would highly recommend Big D cycle in Dallas. They are a real deal Brit shop going back many years. Just visiting their shop is like being in a candy store. They focus mainly on Triumph and Vincent but they are quite capable of doing Norton machine work.

htown16 said:

If you are looking to have machine work done, such as cylinders bored, new valve guides and seats and crank ground, I would highly recommend Big D cycle in Dallas. They are a real deal Brit shop going back many years. Just visiting their shop is like being in a candy store. They focus mainly on Triumph and Vincent but they are quite capable of doing Norton machine work.

Home - Big D Cycle

SELLING AND SERVICING BRITISH MOTORCYCLES SINCE 1963

bigdcycle.com

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I thought they farmed out the machine work?

grandpaul said:

I thought they farmed out the machine work?

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That's what I heard and when I wrote to them asking about boring or where to get it done, I got crickets.

marshg246 said:

That's what I heard and when I wrote to them asking about boring or where to get it done, I got crickets.

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Any work they direct to their machinist, makes their jobs take longer.

P.S. a phone call will work much better than an e-mail.

Consider have the seal conversion work on the kicker, gear change and tach drive.
CNW can do all this.
The oil tank mod is great highly recommended..
They have propensity to leak at the mount.
CNW mod eliminates it..

I wasn't aware that Big D farmed out their machine work. I always just dropped the parts at their shop. I would assume that they hold whoever does their work to a high standard.

htown16 said:

I wasn't aware that Big D farmed out their machine work. I always just dropped the parts at their shop. I would assume that they hold whoever does their work to a high standard.

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Last time I talked to Keith was 2010 and seem to recall him telling me he used a nearby machine shop. Who knows, maybe he bought the shop! I haven't been in the biz since 2018 and the last time I talked to him was when i was picking up a "bitsa" 67 TR6 to fix up for my oldest brother.

I stopped by Big D Cycles on my way to my parents place. They do still do the machining in house on most items. They do outsource some of the more complex jobs but I did not ask too many questions.

I left them the old cylinders to see if they could be saved. Those will be done in house and he said they could also do the heads if I chose that route.

Really nice place and friendly people.
Thanks for the heads up!

RussellTx said:

I stopped by Big D Cycles on my way to my parents place. They do still do the machining in house on most items. They do outsource some of the more complex jobs but I did not ask too many questions.

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I'm really glad to hear that!

I'd take the head in and have them mic the internal guide diameter and valve stems. If they are still in spec you might get by with a light lapping of the seats. But if the guides are worn, they need to be replaced. If the guides are replaced then the seats need to be recut because the seat is no longer concentric with the new guide. If you are putting new guides in you might as well go with new valves and springs. Also, if the valves have been lapped aggressively the seats may need replaced. Getting the head done right is the key to a good running engine. I'd let them do an evaluation of what you have to work with.

The bikes only done 8,500 miles.

Unless you ‘want’ to do it in order to fit fancy new parts, the head should certainly not ‘need’ intrusive work like new guides and seats etc.

A good strip, clean, lapping in, etc is really all that should be needed.

I’d check the springs though. If stood for that long it’s likely the springs on the valves that were open are now compressed a bit. If so, new valve springs would be a nice treat for the old girl.

I’d check the head is flat, again, with that mileage I would assume it will not need a skim, but check, don’t assume !

The "leg bone connected to the thigh bone" syndrome can end up costing THOUSANDS instead of hundreds...

Update,

I chickened out and took the heads in to Big D Cycles and asked them to go through them and get them to spec.

They also let me know that the old cylinders cleaned up at 40 over so I asked them to buy some pistons and match them at 40 over.
I also took the standard bore cylinders and the pistons that I had previously bought and asked them to check out the cylinders and then match them to my pistons if they checked out.

Once I get everything back, I'll have to decide which ones I will use and then I'll have an extra set available if they both turn out ok.

I have slowed down the Norton work and spent more time on other (cheaper) projects while they work their magic.

I also learned about the 'vapor blaster' and I'm collecting parts to convert my harbor freight blast cabinet. I'll see how well I can clean up the engine/gearbox stuff and maybe save some money.

I also started on the gear box. The gear selector was completely locked up so I was pretty worried.
I have it all apart now and it looks like the selector and cam were just gummed up in the bushings...
Is that normal for one sitting that long?
Should I replace the bushings or should they clean up fine?

gearbox pics forthcoming...

Use the plus 40 barrels, enjoy the extra capacity !

Keep the standard bore barrels as spares, they’ll come in handy one day …

Trans looks nice and gooey! my buddie never replaced trans bearings, clean them out real good and reuse.. ( he couldn't hear). For the cost of bearings I always replace them in a bike that sat for years. Removal is easy, set housing in oven and the bearings will fall out!

That Portuguese layshaft ball bearing definitely needs to be replaced with the roller bearing (or Hemmings ball bearing).