timing covers 850 & 750 the same?

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No. ?

P/N 061073 is the 850 timing cover part number.
Parts book says 750's after engine No 212278 are covered in the 850 parts book.
That would be after your bike.

Going to be interesting to see how the earlier covers were different though.
Being absolutely the same - and fitting and working - may be 2 different things ?
 
Rohan said:
No. ?

P/N 061073 is the 850 timing cover part number.
Parts book says 750's after engine No 212278 are covered in the 850 parts book.


061073 is listed from 1969 (20M3S) to 1974, so it should fit all "camshaft points" Commandos from '69 750 to '74 850.
 
There was a difference in form between at least some 750 covers and the 850 item, even the points on cam models. The earlier cover was more rounded in front of the pressure relief valve and had a perceptible valley there and the 850 item was squarer and flatter there (as was the 850 Mk3 which had the chain inspection cap). I once filed an 850 cover to make it look more 750-like but it's mostly hidden by the gear lever anyway.

I believe that they are all interchangeable (but Mk3 requires a different oil pump spigot and rubber due to the enlarged drilling for the anti-drain valve).
 
I have a brand new 850 timing cover on my 71 750, as previously posted the larger rubber seal for the oil pump is required.
 
I have 4 early timing covers (different models and years) and yes they are different castings but functionally the same.
 
Isn't there a difference in the timing pinion spigot depth, or is that between atlas and commando?
 
79x100 said:
There was a difference in form between at least some 750 covers and the 850 item, even the points on cam models. The earlier cover was more rounded in front of the pressure relief valve and had a perceptible valley there and the 850 item was squarer and flatter there (as was the 850 Mk3 which had the chain inspection cap). I once filed an 850 cover to make it look more 750-like but it's mostly hidden by the gear lever anyway.

I believe that they are all interchangeable (but Mk3 requires a different oil pump spigot and rubber due to the enlarged drilling for the anti-drain valve).


Oh thats a worry i fitted an 850 mk3 timing cover on my 750 years ago and i dont remember changing the oil pump rubber seal or dowl! what exactly is the difference? the bike has done thousands of miles like this but i will have to check it now!! ..........baz
 
http://www.norvilmotorcycle.co.uk/

067510 SEAL - OIL PUMP CONICAL - PRE ELECTRIC START
timing covers 850 & 750 the same?



066190 SEAL - OIL PUMP CONICAL - ELECTRIC START
timing covers 850 & 750 the same?
 
splatt said:
Isn't there a difference in the timing pinion spigot depth, or is that between atlas and commando?

I think it's between pre-MkIII and MkIII.

The MkIII intermediate pinion has a different part number - 065667 as it's thinner, the pre-MkIII pinion (20M3S-on) is 061077.

http://www.norvilmotorcycle.co.uk/camcrank.htm
065667 SPROCKET / GEAR - INTERMEDIATE - MK3 - THINNER
 
[="L.A.B."]http://www.norvilmotorcycle.co.uk/

067510 SEAL - OIL PUMP CONICAL - PRE ELECTRIC START
timing covers 850 & 750 the same?



066190 SEAL - OIL PUMP CONICAL - ELECTRIC START
timing covers 850 & 750 the same?
[/quote]
ok thanks for that info i will buy the correct parts and change it over cheers baz
 
L.A.B. said:
061073 is listed from 1969 (20M3S) to 1974, so it should fit all "camshaft points" Commandos from '69 750 to '74 850.
That's the key, points off the cam.

1st commandos running a distributer driven off the rear of timing chest by a second chain required a longer pinion shaft for the double gear to drive the rear chain. They are radically different with no points cover on front.

2nd style is pt. 061073 as per LAB's post (some differences in appearances as noted)

3rd style is MK III
 
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