Problem I Haven't Seen Before

So, I have two parts someone might like - the Atlas? crank being discussed here and a pre-Commando head. They are priced right - come get them and they're yours! The crank is usable - journals good - the superblends go with it since getting the inners off the crank is near impossible without damage. The original keyway in the taper is bad but a new one was cut. Don't know much about the head - came with a bunch of parts - rocker feed on top, not sides.
 
marshg246 said:
Finally got the timing cover off - had to split the gasket with razor blades. Then more nonsense. Auto chain tensioner jammed holding chain super tight. Some sort of anti-sump - maybe AMR, but the parts all fell out so I don't even know if I found them all. Had to use the nuts with thin metal protectors to jack the barrels off - same sealer. Then noticed that the pistons were on the wrong sides and the valves have been lightly touching them - will have to inspect the head and valves carefully - probably would have been worse but the cylinder base nuts were only slightly more than finger tight, and the head was not fully torqued down. Also have to check the piston clearances - it's a fresh bore and if the bores were matched to the wrong pistons no telling what I've got. And, just for fun, one circlip on the right cylinder was in past the slot and the other not to the slot - any chance they would have migrated into place? No, more likely a seized engine! This is the 2nd bike in the group of three that I bought that the pistons were in the wrong sides - best check the 3rd one I guess!

Back to it - lots of gasket scraping to be done.
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Hi Greg, I know people have a scraper , and lots can gouge , the best ever scraper is not sharp but actually 90 degrees , and better still made from carbide , this is a curl steel from a Soudronic body blank welder solid carbide , never lose the edge . Cheers . Vaughn ., fantastic scraper for all surfaces and they don't dig in .
Problem I Haven't Seen Before
 
marshg246 said:
Crank has been split - tabs not bent.
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Quite a few cranks I've worked on haven't had the tabs bent, and I'm reasonably confident that's how they left the factory. It seems they're purely to retain the dowel pin.
That said, you've certainly intercepted some serious issues there!
 
B+Bogus said:
Quite a few cranks I've worked on haven't had the tabs bent, and I'm reasonably confident that's how they left the factory. It seems they're purely to retain the dowel pin.
That said, you've certainly intercepted some serious issues there!
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You may be right but since the parts book calls them a "Nut Retaining Plate", the Workshop says to bend them over, there's no reasonable way to use a torque wrench on those nuts, and bikes I know have never been opened had them bent I think it is more likely an urban legend that people are following.
 
marshg246 said:
there's no reasonable way to use a torque wrench on those nuts,
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A fish/luggage scale on a wrench can be employed as an accurate torque wrench. Divide the scale reading by the fractional foot length of the wrench.

9" wrench is a factor of .75, 6" wrench .5, etc.
 
Dan1950 said:
A fish/luggage scale on a wrench can be employed as an accurate torque wrench. Divide the scale reading by the fractional foot length of the wrench.

9" wrench is a factor of .75, 6" wrench .5, etc.
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Yes, or a right-angle adapter will work as well.
 

Commando Crank Lock-tabs?

I've just stripped the bottom end of the MkIIA that I'm working on. There are no signs that anyone else has been in there, but the lock-tabs - the ones on the two innermost studs that hold the crank together, have never been 'bent over'. Likewise, the others have never been centre-punched...
www.accessnorton.com www.accessnorton.com
 
They make short adapters for awkward places for torque wrenches , first use that I saw was a Chevrolet SB2 cylinder head , this type will work on a norton as well , there must be an altered torque setting .
Problem I Haven't Seen Before
 
It could be that the factory stopped bending them at some point. The majority of the engines I've taken apart that I'm sure (as possible) have never been apart are 72 and 73 750s (mostly 72 Combats). I have never found one of those unbent. This particular engine is known to have been apart and most definitely was going to explode for one of many reasons. I have some 850s that I will take apart if I ever get this one done so I'll check them, one I got from the original owner who says it has never been apart.
 
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Shelby-Right said:
They make short adapters for awkward places for torque wrenches , first use that I saw was a Chevrolet SB2 cylinder head , this type will work on a norton as well , there must be an altered torque setting .View attachment 98730
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I have all sorts of torque adapters. For those two nuts you would need one like you showed that was offset - all I have are straight - and work fine everywhere else on a Norton (although a PITA so I don't usually bother). As long as the torque wrench is at a 90-degree angle to the adapter no different reading is required.
 
I mentioned earlier that the pistons were in the wrong sides. In the picture you can clearly see that the piston marked R is in the left cylinder and the L is in the right. Those are the sides and orientation they came out of. When you switch them to the correct sides based on the marking, they are clearly wrong as the intakes are far apart and the exhaust are close together. It was confusing me, and I was second guessing myself, so I got out an old OEM piston to double check. A little hard to see in the picture but in the red oval is says EX LF so that is clearly the correct side and orientation, and it clearly matches the piston marked R! The pistons are marked wrong! They are JCC. The current Hepolite pistons are also JCC, but they have no side or front/back marking - good thing, I guess!

The two barely visible valve marks could not be made in this orientation so my guess is that the engine wouldn't turn over, so the last builder took the head off, saw the problem and redid the pistons.


Problem I Haven't Seen Before
 
This has been mentioned before IIRC, one of the piston manufactures has indeed got pistons on the market incorrectly marked.
 
TomU said:
If you need them marked, you probably shouldn’t be building the engine.

Just saying :)
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True, but when marked wrong, it sure does get confusing quickly.

Look at the threads on which way unmarked rings go. So much incorrect advice. Most started by errors made by Hastings when they still made Norton rings. There are people here that swear that the bevel goes up on the top ring and down on the second based on the drawings of certain years of Hastings packages. To correct those for a couple of years, Hastings put both compression rings in the same pouch showing the bevel up which is correct, but people think they are in the wrong slot, ask, and people tell them wrong. It didn't help that Hastings did not put the dot on Norton rings for a long time and then when they started again they had reprinted their packaging and made it even more confusing. Also didn't help that the last set I bought was packaged in 2010 and bought in 2020 so when I called Hastings tech support there was a lot of confusion until they realized I was talking about Norton and then said they that all Norton compression rings they ever made were the same and the bevel went up, even on those marked wrong in the packaging and/or with the wrong dot.
 
I was taught as an apprentice machinist this easy way to remember ring orientation, just relate it to your "john Tomas or ya old fella ......if it's IN its up, if is OUT it's down ....easy . So that relates to the internal bevels or external steps etc that help induce ring twist .:-)
 
marshg246 said:
I mentioned earlier that the pistons were in the wrong sides. In the picture you can clearly see that the piston marked R is in the left cylinder and the L is in the right. Those are the sides and orientation they came out of. When you switch them to the correct sides based on the marking, they are clearly wrong as the intakes are far apart and the exhaust are close together. It was confusing me, and I was second guessing myself, so I got out an old OEM piston to double check. A little hard to see in the picture but in the red oval is says EX LF so that is clearly the correct side and orientation, and it clearly matches the piston marked R! The pistons are marked wrong! They are JCC. The current Hepolite pistons are also JCC, but they have no side or front/back marking - good thing, I guess!

The two barely visible valve marks could not be made in this orientation so my guess is that the engine wouldn't turn over, so the last builder took the head off, saw the problem and redid the pistons.


View attachment 98779
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Check this picture:

Problem I Haven't Seen Before
Problem I Haven't Seen Before

According to the owner it ran for 300 miles..

Best.
 
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