New low miles combat, should I worry

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pete.v said:
It is not uncommon to put a good ball bearing on the TS and the high dollar roller bearing on the DS.
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In fact, Norton twins from the very first dommie Model 7 of 1949 were built with a ball bearing on the timing side, and a roller bearing on the drive side. Neither of them high dollar items.

And this arrangement served very well until somewhere into the Atlas/Commando/Combat range (?),
when it seems the loading on the bearings exceeded their load capability.
'Superblends' was the touted solution, although that extra roller seems to be more important, on FAG's anyway...
 
There was already a roller bearing on the timing side on the Combats. It was the same as the drive side.
 
Just ride it an enjoy it just don't over rev it and work on it when needed, keep the maintenance up to it, talk to it and thank it when you get back home safely, who knows it might go forever, when you worry about what might happen of course it will happen because its in head, this is the way I been going with my Norton in the 40 years of ownership and it has never let me down, well once when it broke the rear chain 2 years ago and as it was it was only the joining link that came off, not bad for 40 years of riding it.

Ashley
 
Without pulling the cam chain, i see a brass colored washer up against the inside of the case. The washer has grooves in it. I do not see the tang, but i see a spot on the outer circumference where there is a notch that appears to be where something may have broken off. I assume the removal of the tang has happened already.
 
Bowtoy70 said:
Without pulling the cam chain, i see a brass colored washer up against the inside of the case. The washer has grooves in it. I do not see the tang, but i see a spot on the outer circumference where there is a notch that appears to be where something may have broken off. I assume the removal of the tang has happened already.
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That is very possible. They usually broke off early in the life of the bike.
Hopefully it has been removed from the engine.

I have seen them jammed in the passage that goes from the bottom of the cases to the scavenge side of the oil pump. When that happens the engine usually wet sumps pretty bad when running down the road. [heavy smoke and oil leaks]

When the tang breaks off, about half the time it falls into the timing chest where it does no damage.

The other half the time it falls out into the crankcase and gets picked up with the scavenge oil. That's when the damage occurs. Jim

PS- That was a problem that was discovered early on so the tang may have been cut off when serviced at the dealer.
 
comnoz said:
One thing you should do before you put any miles on it is pull the camshaft sprocket. Behind it you will find a thrust washer with a tang that fits in a hole in the case. Cut the tang off and reinstall the washer.
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That will only cure half the problem as the same thrust washer with a tang is fitted inside the case (between the conical trustwasher and the case).
 
nortonspeed said:
comnoz said:
One thing you should do before you put any miles on it is pull the camshaft sprocket. Behind it you will find a thrust washer with a tang that fits in a hole in the case. Cut the tang off and reinstall the washer.
Click to expand...

That will only cure half the problem as the same thrust washer with a tang is fitted inside the case (between the conical trustwasher and the case).
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True, but for some reason that one was not known to break early like the outer one was.
Of course I would remove that tang also if the motor was down. Jim
 
There is a theory that the main bearing failures on combat engines was due to a change in spec on the contact breakers, which resulted in the ignition timing shifting a saving of 10p on each bike cost the company millions.

My main bearings went at approx 5000 miles in 73, I then fitted a Boyer. Pity about the engine dropping a valve ousands of miles away from home when I was in Israel.
 
chasbmw said:
There is a theory that the main bearing failures on combat engines was due to a change in spec on the contact breakers, which resulted in the ignition timing shifting a saving of 10p on each bike cost the company millions.
Click to expand...

Another Commando myth perhaps? I would think any apparent change made to contact breaker (or AAU) spec. is far more likely to have been dictated by Lucas, rather than Norton, however, the contact breaker and AAU part numbers listed for 1972 are the same as used previously so where exactly are they supposed to have saved this "10p"?
 
I'd ride it and see how it goes. I just replaced the main bearings on a Combat that had 42,000 miles on them. They went gracefully with a rumble.
 
I do plan on just riding it. I noticed when I was working on it that the lower case halves were sealed up with sealant, so I assume the lower end has been apart in the past. Finished the pazon EI and points seal install last night, so hope to fire it up tonight. My only real worry now is that the camshaft isn't perfectly centered in the points seal and Im worried the points seal will keep leaking.
 
Got it running tonight. It starts first kick, but the idle fluctuates quite a bit up and down. Im assuming the slides in the carbs are shot. And just as i feared, the new points seal is leaking already. Theres a steady stream coming out where the ignition wires go into the timing cover like before. I used the seal install tool, so im not sure that another seal will stop it.
 
Bowtoy70 said:
And just as i feared, the new points seal is leaking already. Theres a steady stream coming out where the ignition wires go into the timing cover like before.
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Presumably, you checked the oil is actually leaking from the seal-as that oil could be leaking from the timing cover joint?
 
L.A.B. said:
chasbmw said:
There is a theory that the main bearing failures on combat engines was due to a change in spec on the contact breakers, which resulted in the ignition timing shifting a saving of 10p on each bike cost the company millions.
Click to expand...

Another Commando myth perhaps? I would think any apparent change made to contact breaker (or AAU) spec. is far more likely to have been dictated by Lucas, rather than Norton, however, the contact breaker and AAU part numbers listed for 1972 are the same as used previously so where exactly are they supposed to have saved this "10p"?
Click to expand...
Ok it wasn't just the contact breakers

New low miles combat, should I worry
[/New low miles combat, should I worry
 
chasbmw said:
Ok it wasn't just the contact breakers
Click to expand...

The underlying problem was more to do with the AAU, and stemmed from Norton's decision (in 1969) to move the points assembly and drive the AAU from (chain-driven, 4 lobe) camshaft and the Combat cam just appears to have made things worse-but it's all there in the article although apparently, Lucas never sanctioned use of their AAU under those conditions but eventually produced the improved (54425656) AAU.
 
The original Boyer I fitted back in 73 incorporated its "black box" into an extended points cover a 1/2" alloy spacer was provided. It was later that Boyer moved the electronics into an external black box.

I can't remember why I fitted the Boyer back then, probably I was fed up of adjusting the points and saw the Boyer as an improvement. I seem to remember easier starting and the Boyer was reliable during my brief period of ownership.
 
One Wonders if the British Motorcycle Industry would have survived if theyd fitted electronic Ignition to about everything by say 1970 .
wouldve saved an enormous amount warenty problems .
 
chasbmw said:
I can't remember why I fitted the Boyer back then, probably I was fed up of adjusting the points and saw the Boyer as an improvement. I seem to remember easier starting and the Boyer was reliable during my brief period of ownership.
Click to expand...

That brings back memories. I certainly recall being fed up with those points and learned of the alternative. It was the first "set it and forget it " experiences of my life. The difference was truly profound. Now with the maggie, it is another profound difference.
 
Boyer say that they developed their ignitions because the racing 3 cylinder triumphs and BSAs where incapable of keeping the 3 sets of contact breakers in Time.

The British M/C industry was incapable of making proper long term investments!
 
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