1974 Commando 850 Barn Find

Ah, the photos always do look too good to be true. Bores do look good. I'd see if the flash rust cleans up with oil and a rag, or, if you're concerned, lightly hit it with a 320 grit Brush Research flex ball hone in a drill with solvent and just use the same pistons and rings. Some people like me really admire low mileage original bikes, warts and all. In any case, a very good score at that price.

marshg246 said:

The ones you've marked drive have a "V" (bevel) showing. That "V" goes forward. I'm assuming you mean that you're looking from the perspective of behind the cylinders. If so, the drive side was in backwards and the timing side was in correct. In any case, the "V" goes forward on both sides.

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You’re correct on the perspective, it’s from the back looking forwards. My issue is that the two drive side follows have the bevel on the same side. I.e. if I spin them around there will still be one bevel facing forwards, and one back.

No plans to move the followers to new positions/cam lobes, just checking on that one that has the bevel on the wrong side. Faces of the followers and lobes look good.

Hammerski said:

You’re correct on the perspective, it’s from the back looking forwards. My issue is that the two drive side follows have the bevel on the same side. I.e. if I spin them around there will still be one bevel facing forwards, and one back.

No plans to move the followers to new positions/cam lobes, just checking on that one that has the bevel on the wrong side. Faces of the followers and lobes look good.

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OK, I see it now. Are the timing side tappets right? Most likely, someone changed just one tappet and used the wrong one of a pair.

marshg246 said:

OK, I see it now. Are the timing side tappets right? Most likely, someone changed just one tappet and used the wrong one of a pair.

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Exactly. The timing side tappets are correct. If the mismatched set on the drive side isn’t a problem I’ll just keep it the way they came out.

Hammerski said:

Exactly. The timing side tappets are correct. If the mismatched set on the drive side isn’t a problem I’ll just keep it the way they came out.

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I suspect that it will be OK as long as the lock plate is able to do its job on that side and they run smoothly. I would verify that the surfaces between them that touch ride OK - I've never looked at a mismatched pair to see if they do.

Anyone here remember the range of "chocolate" cams? Those are the most susceptible to rapid wear if anything it amiss in the interface with the followers. If the cam looks good, leave the followers as they are! (or, send cam and corrected set of followers to Megacycle for re-facing).

johnm said:

Nice. The engine no is less than 150 off my bike. It will have been built late August 1974. See the roll on the bottom edge of the front guard. Genuine but you won't see it on any modern reproduction.

It's a valuable original example because for example while it's clearly a Mk2 not a Mk2 A it displays some of the features that some insist define an A variety. For example the notch in the rear chain guard for the inspection hole in the rear brake plate. It will also have the frost plugs on the end of the swinging arm spindle.

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What? You mean my early '74 MK2 non-A is worth mkre than I thought? CHEERS mate

Be sure to R.P.P.O.S. (Replace the Portuguese Piece Of Sh!t) layshaft bearing in the gearbox.

Tornado said:

What? You mean my early '74 MK2 non-A is worth mkre than I thought? CHEERS mate

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Nahh, it's a pile of pooh. Not even worth the effort to wrench on it.
I'll give a 1k to relieve you of the misery. But you'll have to ship it to California....

MichaelB said:

Nahh, it's a pile of pooh. Not even worth the effort to wrench on it.
I'll give a 1k to relieve you of the misery. But you'll have to ship it to California....

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At the current usd/cad exvhange rate that's not such a bad deal, eh? But you'll have a very large tariff applied as the importer...im afraid the bike is not USMCA compliant.

Hammerski said:

Yeah, the previous owner had it running so I'm sure it wouldn't take much, but then what's the point? The front brake was full of rust, cables fraying apart, speedo cable broken, isolastics sagging, valve seats speckled with carbon or rust, trans full of what appears to be chocolate milkeshake, oil everywhere from an unidentified leak(s), and a dozen other problems. To actually have a bike capable and trustworthy enough to ride serious miles, I think its easier to just tear it down to the frame, clean everything, and put it back together. My opinion is that its better to have something that functions as good as possible, rather than keeping it as original as possible.

Interesting point on the green wires, I didn't give them a second look when I saw replacements were only a few dollars. I dug them out of a box today and they cleaned up well, I'll keep them on if they still work.

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Smart move.
I found and purchased a 74 MK II. Located it in a barn in Nevada. No rust. Under a collapsed hayloft covered by a tarp. 1300 miles on the odometer.
It had been sitting for 43 years
Common sense says take it apart and go through it. Just changing the oil and cleaning out the carburetor is a long long way from offering a safe ride.
The right approach was go through that bike component by component from the inside out. There were a lot of hidden issues that would have shown up at the wrong time.
I need to know that it's safe, from every aspect.
Just giving it a quick once over and then going for a ride to "see how it runs" has a huge downside.
If all you are seeking is an original show piece not to be ridden no point in going deep into it.
IMHO your decision is a good decision.

Cleaning up the heads and noticed the exhaust ports look like they've been opened up with a die grinder. Is this standard from the factory or has someone been in here doing some porting?