At what engine number was the starter motor position (behind the barrel) introduced on the 750?

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dobba99

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I am going through a clients early 750 engine (the engine number dates it to around June/July 68) and i'm sure it has odd crankcase halves. The number stampings found inside the crankcase don't match and only one dowel was fitted when i split the case. The timing side has the blanking plate where the starter was going to be fitted. That was before that idea was dropped until the 850 Mk3
 
That blanking plate was for the magneto and later distributor. The starter was never mounted there. By 68 the points had migrated to drive directly off the camshaft but on the Commando. 68 featherbed (last year) models (Mercury) I believe still had the distributor. The short answer to your question is that that position on 750s and others mounted the magneto from before the first 750 Atlas and continued on to early Commandos.
 
I believe that to be 136618 although there is another number (133618) but I think that's a misprint.

Thomasa said:
That blanking plate was for the magneto and later distributor.
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That is not correct, the blanking plate was for a starter motor.
 
That's news to me. I have a 66 750 Atlas with the magneto mounted in that position and know of much earlier bikes with a magneto in that position. So whatever they expected to do with the hole, it had previously mounted the magneto and had to be blanked off with something. Later the castings eliminated the hole altogether.
 
L.A.B. said:
I believe that to be 136618 although there is another number (133618) but I think that's a misprint.



That is not correct, the blanking plate was for a starter motor.
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That nails it, definitely different halves.
Many thanks for that
 
Thomasa said:
That's news to me. I have a 66 750 Atlas with the magneto mounted in that position and know of much earlier bikes with a magneto in that position. So whatever they expected to do with the hole, it had previously mounted the magneto and had to be blanked off with something. Later the castings eliminated the hole altogether.
Click to expand...

No you're getting your timeline mixed up. When the points housing was changed from behind the cylinders the casing then became solid (second picture in the link, below) and the starter motor blanking plate case was introduced after that (third picture). Also the bolt spacings are different.
http://atlanticgreen.com/engcases.htm
 
The 750 was supposed to have had a Lucas starter motor however the factory could never get it to work reliably so it was never fitted.

At what engine number was the starter motor position (behind the barrel) introduced on the 750?
 
Hmmm... So what years have the starter blanking plate? Many came through our shop like that but I never paid attention to which ones had the blanking plate. When you have a row of bikes to do a cycle service on they all sort of meld into one another, especially when one is cursing the air filter element and those damn bolt heads scrape your knuckles.
 
Thomasa said:
Hmmm... So what years have the starter blanking plate? Many came through our shop like that but I never paid attention to which ones had the blanking plate. When you have a row of bikes to do a cycle service on they all sort of meld into one another, especially when one is cursing the air filter element and those damn bolt heads scrape your knuckles.
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coupled with LAB's engine number 136618 (late 70) will give you the details of the changes. Its not on my 72 so not on long.
 
Thomasa said:
That blanking plate was for the magneto and later distributor. The starter was never mounted there. By 68 the points had migrated to drive directly off the camshaft but on the Commando. 68 featherbed (last year) models (Mercury) I believe still had the distributor. The short answer to your question is that that position on 750s and others mounted the magneto from before the first 750 Atlas and continued on to early Commandos.
Click to expand...
If you take a look at the blanking plate you will see that the 3 bolts are not symmetrical like a magneto
Well at least on my 750 it's not
 
I remember reading that one of the Norton test riders, Bob Manns I think, could tell when the problem was likely to happen. One day when Dennis Poore was standing near the bike, Bob pressed the starter button & the crankcase broke. The starter idea was abandoned from that moment.
 
The parts book shows the '72 cases as having the blanking plate, but neither of mine had the plate. Current Combat is 2082XX, previous '72 was 2006XX
 
The electric starter aperture was supposed to have been deleted from serial 205024, however, I'm not sure that number is entirely accurate.
 
I dugout this old thread about the failed starter (which interestingly was made by Lucas - TVS in India) For those that aren’t aware, TVS now owns the Norton brand.

L.A.B.

Post in thread '1972 750 Starter Motor'

marston rhode said:
First post 'cos it's something I was involved with, briefly..
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Welcome to the forum, marston rhode.

And, if you do happen to have any other "factory" Commando anecdotes or interesting accounts about what went on at the AMC or Norton works during the Commando production period that you would be willing to share with us, then I'm sure our members would love to hear them?
_______________________________________


It would appear Norvil Motorcycles also has some of those Lucas starter motors:


http://cgi.ebay.co.uk/STARTER-MOTOR-Luc ... 335a78d97b

I believe a similar motor...
 
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