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1973 850 commando....

Classic Norton Commando Motorcycles.

Re: 1973 850 commando....

Postby Rohan » Wed Apr 05, 2017 9:50 pm

keso wrote:.whats the difference between interstates...roadsters...


The 850 Roadsters and Interstates are all the same - mechanically - underneath.
For the Mk1 850 and Mk 2 850 anyway. The Interstates had low flat mounted mufflers,
which many owners have since replaced with upswept peashooters.

However, there was a quieter version of these, the Mk1A and the Mk 2A, that had plastic airboxes and
blackcap mufflers. These were made alongside the 850 Mk 1 and then Mk 2 models.
The quieter ones are supposed to be a bit slower than versions with the tweety/whistler mufflers.

keso wrote:.was there ever a super commando?..


Yes and no. No for the 850 Commandos anyway.

For the earlier 750 models, for 1972 ONLY there was the Combat 750 version.
It had a hotter (Combat) cam and 32 mm carbs, and a claimed 65hp over the stock 60 hp.
And a disk front brake.

Note that this seems to be marketing hp, it was more like ~46 or 47 hp v's ~42 hp at the back wheel.
The Combats were the ones where the engine/crankshaft/main bearings/gearbox grenaded in
a few thousand miles !!!
And led to a LOT of warranty claims, mucho dollars down the drain for Norton. And egg on face.
Back to the stock cam for all later 1972 750s, and for ALL 850 models.
And fitting famous FAG 'Superblend' bearings for long crankshaft life.

However, the factory issued several tuning sheets for 850 owners to make their own Combat 850 version,
although owners are encouraged to try the stock 850 version first, its pretty strong and torquey
in the engine dept, whereas the Combat cam makes it somewhat revvy - and possibly fragile ??
A crowd called Drouin also made a supercharger kit for Commandos.
Ditto the remarks about becoming fragile, although several survive even amongst members of this forum.
Must be very gentle with the wrist ???
hth.

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Re: 1973 850 commando....

Postby Mr. Rick » Wed Apr 05, 2017 10:43 pm

Fuel lines go from $60 to $80. P/N is 06-5192 Here's one on eBay, although I'd recommend using one of the vendors mentioned earlier by Ekvin:
http://www.ebay.com/itm/Norton-Commando ... wR&vxp=mtr

With only 9000 miles the floats and needles should be okay, but the whole carb will need to be cleaned out. I had a float with a hole in it once, but that's pretty easy to check.
A couple of sets like this would certainly not hurt:
http://www.ebay.com/itm/AMAL-CONCENTRIC ... ve&vxp=mtr
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Re: 1973 850 commando....

Postby L.A.B. » Thu Apr 06, 2017 3:07 am

keso wrote:...and was wondering..my bike is a 1973 850 commando...whats the difference between interstates...roadsters...



http://www.classicbike.biz/Norton/Broch ... LineUp.pdf
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Re: 1973 850 commando....

Postby chasbmw » Mon Apr 10, 2017 3:16 am

It's easy enough to fit a roadster tank onto an Intertate. Emgo make a decent roadster tank, but as far as I know don't make an interstate tank.

You will have to bite the bullet and replace the tank, fiberglass and modern fuel does not mix and sealing a used fiberglass tank is a crapshoot.
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Re: 1973 850 commando....

Postby keso » Mon Apr 10, 2017 1:24 pm

Going to try a caswell seal on the tank....which petcocks do you recommend?also...aftermarket or original on the air filtration?

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Re: 1973 850 commando....

Postby chasbmw » Mon Apr 10, 2017 1:28 pm

Cleaning a fibreglass tank well enough to take sealant is a bit more difficult than steel. What do Casewells recommend for fibreglass tanks?
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Re: 1973 850 commando....

Postby keso » Mon Apr 10, 2017 1:40 pm

Ok.... my friend thats working on it just told me the tank is metal!!..When I pounded the outside it felt heavy like fiberglass..but he put a magnet on the outside and on the inside hump that the frame sits on and it stuck!!! was there a metal inside layer or something? the filler neck is metal......I was 99% sure it was not metal!! anything I'm missing???

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Re: 1973 850 commando....

Postby chasbmw » Mon Apr 10, 2017 1:51 pm

Put the magnet on the outside of the tank......
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Re: 1973 850 commando....

Postby keso » Mon Apr 10, 2017 2:52 pm

Did that...still sticks...were the tanks made out of both??

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Re: 1973 850 commando....

Postby L.A.B. » Mon Apr 10, 2017 3:01 pm

keso wrote:Did that...still sticks...were the tanks made out of both??


No, so it is steel (as it should be) after all.
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Re: 1973 850 commando....

Postby keso » Mon Apr 10, 2017 5:26 pm

Ok..am do I g a pot 15 kit on the tank...recommendation on petcocks?

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Re: 1973 850 commando....

Postby chasbmw » Tue Apr 11, 2017 12:55 am

Good news that you have a steel tank, it was a major aground on my Fastback to source and then seal an Indian made tank.

Just ensure that Casewells warrant that their sealant is proof against ethanol as some earlier sealants failed with the introduction of ethanol.
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Re: 1973 850 commando....

Postby peter12 » Tue Apr 11, 2017 1:22 am

If the tank is steel and clean Im not sure it needs a sealant. Check carefully first but this may avoid an expense and a lot of agro. I have an original steel interstate tank, use pump fuel and have no issues whatsoever.

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Re: 1973 850 commando....

Postby JimNH » Wed Apr 12, 2017 3:57 am

Just clean the tank with a mild acid; even vinegar will work. Check youtube; here's one, not vinegar but will give you an idea how clean you can get them. Don't line it, it doesn't need it.

https://www.youtube.com/watch?v=fBQX5v4FmzI

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Re: 1973 850 commando....

Postby keso » Thu Jul 27, 2017 7:12 pm

Ok.....update...a little more work has been done...but lots more needed...my intent is to get it running and try to keep it original....but have a couple of problem areas..we are rebuilding the front master cyl..and caliper...I need a brake switch(just see aftermarket..)..my original key switch is non functional..if we jumper it lights start working?..is there a was to "free up" this switch or should I purchase new?A bigger issue is when we cut the wire holding the exhaust nuts we saw that the head is somewhat stripped..the nut threads appear fine..any solution here short of getting a new head? Also both spark plugs were mismatched..a b7es..and a br8es...manual shows b7eb-11..which should we use?...Thanks in advance...

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