Project update: very good, then a very bad day

Yesterday started awesome. Home early from work my ‘72 started on the first kick. I’ve got about 50 miles on it since getting it running so the plan was to heat it up and change the oil.

Got sidetracked and had to pick up the kids so the oil change didn’t happen until later. The bike was cold by then and it was nice out so I used the excuse of warning it up to take another ride. It started on the first kick. Took it for a ride around the airport. Almost home I had some noise and loss of power until it quit. Had the clutch in quick and Coates to a stop. Not try to start it, I tried to gently kick it through to see how bad it was. First kick went through, second kick stopped hard. After a long walk home heres what I found:

1. Was able hand to turn the engine back but it stops in the same spot forward
2. Drained the case first then the oil tank. Oil looked normal for a bike that sat (fresh oil about 50-60 miles ago). It had a little light sheen and no chunks that I could see. And nothing much stuck to the screen in the tank.
3. Both the intake and exhaust valve see to me open on the left cylinder.

I’ve got some work ahead of me from what I think is some type oiling issue causing damage. Up until this bike ran well but leaked oil a little from just about everywhere so it was going to need to be taken apart anyway.

After I build a new bench I’ll post pics and an update of the engine tear down.

In the meantime I need to get excited and starting this project 6 months early with an added challenge of whatever the hell I did to it yesterday.

Would appreciate help with:

Ideas of what has happened. I’m thinking cam/ tappet failure

Sources for all the rebuild parts I’ll need. Doesn’t look like there are many kits. Will need a good list.

Your favorite upgrades. I’m not a purist and I plan on riding this thing. Would like to keep it as original looking as possible. I like the kick start.

Thanks in advance! Pretty disappointing day but after a sleep on it I’m exited for the end result. It’s just money right? They print more of it everyday.

Sounds to me as a bent or broken valve. Have you taken out the spark plugs?

"Your favorite upgrades."

Oil pressure gage

concours said:

"Your favorite upgrades."

Oil pressure gage

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I set you up good for that one! Lol!

Plugs were removed and nothing looks too weird up top. Just the intake on left appears open. Maybe exhaust was out of spec, I can feel movement now.

Afraid the trouble is to the south.

You can rebuild a motor with some very good parts for around $3KUS. Finding a machinist that knows Nortons and won't put you on a 1 year waiting list is the challenge. The bike will still look stock. Check out the JS Motorsport website.

Did anybody mention that the rocker spindles might be in upside down? I don't know what happens under those circumstances, but it probably isn't good.

Have you gone to a metal tank? If not maybe the dissolving fiberglass tank has coated the intake valve stems and stuck one of them.

Chris said:

As Mike says plugs out & use a torch to look down the plug holes. Probably a stuck valve.

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One of the things one must get used to is the vernacular between the countries.
One man’s torch is another man’s flashlight.

MichaelB said:

One of the things one must get used to is the vernacular between the countries.
One man’s torch is another man’s flashlight.

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I’ve been wrenching on Brit stuff for 30 years so I’m familiar with the vocabulary.

I could see how that could cause some serious trouble in a US shop though!

batrider said:

Have you gone to a metal tank? If not maybe the dissolving fiberglass tank has coated the intake valve stems and stuck one of them.

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Have a crappy metal tank on it now. I dont think it’s a stuck valve.

Coolhands said:

I’ve been wrenching on Brit stuff for 30 years so I’m familiar with the vocabulary.

I could see how that could cause some serious trouble in a US shop though!

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Ya, 52 years ago I asked a guy in a Triumph shop how it was possible to clean parts in paraffin. Before he explained that it was British for kerosene, I had all kinds of crazy thoughts like melting it on parts and peeling it off with the dirt!

Update: somewhat good news? Still won’t move past left cylinder intake stroke but all the valves work and the cylinders move up AND down.

So no matter what I end up finding when I crack this thing, it could be worse, right?

As you tear into the motor, check both timing and primary for obstructions first. It could be something that has come loose around the alternator or cam drive. Also I experienced a similar condition once when using bolts that were a bit too long for the three that hold the inner primary to the engine case behind the alternator.

1 bolt for a quick look ina primary.

Since you already know the valves work; and, since you must to do anything much in the engine, I would take the timing and primary covers off and look for obstructions before taking the head off. You could then pull the clutch and turn the engine with the rotor nut to see if it's really the engine.

I would take the primary cover off first.
Removing and replacing the timing cover for a looksee has been known to cause engine destruction.

Glen

Pistons move up and down. If the cylinders were moving up and down all kinds of hell would break loose. Just giving you some BS.

Kind of reminds me of when something gets dropped into the crankcase that does not belong there and it is getting wedged under the crank and stopping the crank from moving. However, you've put miles on it, so it's a mystery.

Check the primary chain case
See if any of the chaincase to engine bolts have dropped out onto the primary chain

"heard some noise and loss of power, then it stopped" hints at motor problems. If something in the timing or primary side got loose I think there would be a lock-up of the motor