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Hi all, Andy here. How do I post a photograph on this forum, can anyone tell me?

Always wanted a Norton Commando but restrained myself as I've never been able to leave any of the 30 odd bikes I've owned standard and didn't want to ruin someone's labour of love. However, recently I came across a modified 850 on the net. It was for sale at an amazing price. Showed my wife the pics and her response was, and I quote word for word:

"mortgage the kids"

I'm very lucky as I'm married to a girl who rides a motorcycle like she just stole it and calls me "the fun retarder". Life doesn't get much better than this.

The modifications on this bike where so many that the idea of stuffing up someone's labour of love was of no concern so I bought it. Once home the task of getting things to a standard I'm happy with have begun. All the mods I'm fixing/adding are left cosmetically unfinished at the moment. Once I'm satisfied with the overall package (as if that will ever be the case says the wife) the thing will be stripped to the last nut and bolt and full rebuilt mechanically/cosmetically.

Although the overall look/aesthetics of this bike are great, several existing mods are quite impractical. The worst of these is the oil tank mounted high up between the subframe rails and having a capacity of well over 5 lt. This is probably one of the reasons the thing wheelies so easily (great fun I must admit). Anyway here's the story of what I'm doing to resolve this issue.

Firstly, I'm looking for a secondhand Norton Commando 750 "S" exhaust system. The system with upswept exhaust pipes on either side of the engine. Am interested in all different components of this particular system. If anyone has any parts they are willing 2 sell please contact. I have a set of 750 "SS" exhausts pipes to sell/exchange if a deal can be struck.

I'm looking for these parts to get the exhausts out of the way under the frame rails as the next step, once fitted is to make a stainless steel, underbelly oil tank (should solve the wet sumping issues at least). I intend to make all oil line connections dry break to aid with oil changes etc and eventually have the tank coated mat black to make it as unobtrusive as possible.

On that note, any advice on setting up the oil system would be appreciated. I believe I should be able to simply reverse the oil pump lines to ensure that the engine receives oil from the tank under pump pressure rather than with gravity assistance. To do this I will need to determine the output pressure of the oil pump and set up a bypass sytem to regulate the flow/pressure if proves too high.

Following successful setup of this tank/oiling sytem the next step is to mount all the electrics on a flat metal plate between the subframe rails. With the inclusion of all modern electrical components, including a battery eliminator and secret wiring that should leave the entire area where the original oil tank and battery would have been mounted totally devoid of any components.

I'll ride it like this for a while and decide whether to mount a single shock setup although at the moment I'm leaning towards the existing twin shock setup for aesthetic reasons. Maybe I'll just mount some high quality shocks and a stronger swinging arm.

I have a both Paypal and Visa accounts as well as access to a Bank of England account plus both UPS and Fedex shipping accounts, so payment/frieght should pose no real problems. Hopefully someone out there will be able to help me on all counts.
 
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To get some good ideas, Look into what Kenny Dreer did early on putting the oil in the frame. On a dry sump system the scavange side runs a double the pressure side so reversing the lines is a no no. Later Commandos have high pressure top end lube so lowering the tank is possible. Just don't forget a filter on the return side. Three quarts US is minimum. Making the oil and filter easy to change should be a design priority. Perhaps one of the owners of a early Dreer Norton could do a show and tell on the oil set up. I know your out there.
 
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Thanks for your replies so far guys. Norbsa48503 reply raises several questions as follows:

"To get some good ideas, Look into what Kenny Dreer did early on"

With this comment are you referring to the '70's Norton Commandos modified and remanufactured by Kenny Dreer at Vintage Rebuilds of Gladstone, Oregon?

Are they oil in the frame modded? I did think of this idea early on but dismissed it as to much trouble to enlarge the main frame top tube that would logically be used for this purpose.

Am I wrong? Is the main top tube of sufficient internal capacity to allow this mod? If this proves to be the case I think this would be a far more logical idea than a belly tank.

If I have to stick with the belly tank idea the your reply raises some questions specific to this mod.

"On a dry sump system the scavange side runs a double the pressure side so reversing the lines is a no no."

Are you saying that if I reverse the lines the pressure side won't provide enough flow to scavenge efficiently?

If can do this mod successfully, even with what you're saying, using the scavenge side as the pressure side should only require some sort of pressure bypass sytem, surely?

"Later Commandos have high pressure top end lube so lowering the tank is possible. Just don't forget a filter on the return side."

Does this mean if I have a late enough motor this mod is possible because of the higher pressure top end lube system? If so how do I tell if the motor is of this later/late enough design?

Thanks again guys, eagerly awaiting your replies

Andy
 
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Yes, Kenny used the top tube as is in size just added a spigot near the neck for filling and a drain spigot down below for draining.New system held just under three US quarts so lots of changing. I hear he's back in busness at vintage Rebuilds he could do this for you?
Yes a motor designed for dry sump must be kept dry reversing the lines is not worth all the other reverse enginnering you would have to do.
Early Commando and not too many had the old scrolled rocker shafts. You will be pulling these on a normal go through of the motor and will see them.
If you had this old low pressure system it feeds the top end via gravity like Triumph and older BSA's so a belly tank wouln't do because you can't make this system run up hill.
Filters must always be in the return line this way if they plug your motor fills with oil instead of starves for oil. There are many other reasons I could go on...
 
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AndyP, not trying to stiful your thinking here always good to hear from someone so excided and ready to re-engineer. Go to the page behind this one, see page two, down just a bit see the thead Commando improvment list. See the links to Regs page this has been going on a long time. You have plenty to do belive me when I say this you are never done with a Commando. When you get it running or better yet ride a well sorted one you will really go nuts. The cam and the crank are were all other mods come from I just wish that when I started mine many moons ago someone grabbed me and got this thru my head. How much HP leads to How much RPM leads to what kind of carbs and so on and so on. Ride some Nortons before you start they are a touring bike that handle very well when built well. But the fastest Commandos on the track still get thier ass wipped by old Norton Manx 500 every time so don't fool yourself. When you ride a good Commando it's hard to go back and ride old Triumphs and Bsa's for any distance. Latley we see people buiding thier motors for low end grunt not top RPM HP. It changes everything you do so ride both kinds before you jump.
 
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Another reason the belly-tank does not work is the return being double the capacity of the feed has lots of air in it. As you plan to run a sealed tank the pressure would build up and would need to be vented in some way whilst still using pressure to force the oil up.
 

L.A.B.

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AndyP said:
I believe I should be able to simply reverse the oil pump lines to ensure that the engine receives oil from the tank under pump pressure rather than with gravity assistance.

I think all that would be accomplished by doing that would be to reverse the flow across whatever oil tank you chose to fit. If that happened to be a standard design of tank then oil would be fed in at the bottom and air would be drawn into the feed side of the pump resulting in a wrecked engine in a very short time!



Oil circuit diagram http://www.oldbritts.com/oillines.html
 

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norbsa48503 said:
Later Commandos have high pressure top end lube so lowering the tank is possible.

norbsa48503 said:
Early Commando and not too many had the old scrolled rocker shafts. You will be pulling these on a normal go through of the motor and will see them.


All Commandos (and also a thousand or so Atlas models beforehand, starting at engine number 116372) had high pressure lubricated valve gear I believe,-so no scrolled rocker spindles should be found in a Commando 850??

norbsa48503 said:
If you had this old low pressure system it feeds the top end via gravity like Triumph and older BSA's

They were not fed by gravity, but by the lower pressure scavenge system.
 
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Yes L.A.B. you are right top end fed by return line to tank. A stepped down dia. feed line that flows so slow that we always called them gravity feed. But I still wouldn't want the tank down below with this system. Iam thinking that gavity would dain the line and it the flow rate you would starve the top end. As you say all long gone by the 850.
 

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I feel Andy's idea is a solution looking for a problem where one doesn't really exist, but gravity could be useful with a belly tank, as the scavenge system would probably no longer be needed!

As a gravity drain between sump and belly tank should be all that is required,-so the scavenge side of the pump becomes redundant and the supply side configured to draw oil from the tank?

However.....(a theory)
I think the scavenge side of the pump could possibly be used instead of the supply side in order to increase flow/pressure?

If the scavenge side picked up oil from the belly tank it could then follow its normal route out of the return pipe from the engine, through a short pipe to a cartridge filter, and back to the engine, the oil entering through the supply pipe.

If the pump supply gears were removed the oil would flow directly through the supply side of the pump to the timing cover gallery as normal?

The oil tank would not need to be pressurised. But some modifications to the oil pressure relief valve could be needed as it is unlikely that it would be able to cope with the increased oil flow? Some restriction may also be needed in the supply to the valve gear to prevent over-oiling?
 
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As you say the crank don't need double volume and the top end is already in trouble. I put the Norvil high volume pump in mine and as near as I can tell only got more oil leaks. There's a great story about Harley spending millons to fix thier old oil system about the time of the 883 it's not easy even if you have lots of dollars. What they found was worth the coin they were over oiling to a large degree doing more harm than good. It's the internal passages running backwards that I find hard to grog. I am thinking that half an oil pump would be no oil pump. Wouldn't you need the gear in there to keep the chambers sized right?
 
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Andy

Posting pictures.. not real hard.. I finally worked dit out via this link so . that's a good indicator lol
http://www.ibdguy.com/posting.shtml

Hows cold old Melbourne this year.. ?
Bloody wet and cold in Far north QLD I tell you ~

R U in the NOC Melbourne ? I used to share a few beers with the boyz ~ and goils ~
 

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norbsa48503 said:
I am thinking that half an oil pump would be no oil pump. Wouldn't you need the gear in there to keep the chambers sized right?

No I don't think so, as both supply and scavenge sides of the pump operate separately, the only common moving part being the drive spindle, if the supply driven gear is removed then the oil that is being circulated as described in my theory (out to the cartridge filter, and back to the inlet and onward to the supply side of the pump) if (at least) the driven gear is removed and possibly the teeth would need to be machined from the supply drive gear (if they they mask the pump ports) then the oil would flow straight through the supply gear chamber and on to the timing case gallery.
 
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I think that with this sort of fundamental experimental work, the chances of getting it right first time are probably not that great. The consequences of getting it wrong will probably include con-rods flailing frame tubes (and the under-belly oil tank)

By the way, what state of tune is the motor in or is my old chuffer the only Commando that doesn't wheelie ? :oops:

Is there actually enough space under a Commando motor to position a tank without hindering cornering clearance or ground clearance over road irregularities, dead kangaroos, next door's cat and that sort of thing ?

Oil in frame is very do-able. Internal baffling is probably a good idea but watch out because the short cross tube where the rear subframe tapers under the seat nose is actually one length that goes right through the spine so getting up inside is not that easy.
 
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Stuart SS said:
Andy

Posting pictures.. not real hard.. I finally worked dit out via this link so . that's a good indicator lol
http://www.ibdguy.com/posting.shtml

Hows cold old Melbourne this year.. ?
Bloody wet and cold in Far north QLD I tell you ~

Melbourne's been great this year, only a couple of really cold weeks so far.
Bloody wet I can understand in FNQ but COLD? Sounds to me like ur sooking on Stuart (LOL)

R U in the NOC Melbourne ? I used to share a few beers with the boyz ~ and goils ~

Not yet, been far 2 busy with kids, wife's DS7 Yamaha, terminally ill father inlaw, Vince Messina and Alison Scoular's sidecar, studying for uni, making a living and having the odd quiet beer with my mates not to mention the world cup and now I'm staying up each night for the Tour de France etc. but I do intend to get around to it. By the way can you really sleep when your dead or will the devil find something to distract me then as well?
 
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79x100 said:
I think that with this sort of fundamental experimental work, the chances of getting it right first time are probably not that great. The consequences of getting it wrong will probably include con-rods flailing frame tubes (and the under-belly oil tank)

That's why I'm asking the questions but all is not lost as there is a spare motor in the shed and if I blow them both getting it right that will give me an excuse to build a Steve Manney equipped engine. If you've never heard of this guys check out this link:

http://www.stevemaney.com/

By the way, what state of tune is the motor in or is my old chuffer the only Commando that doesn't wheelie ? :oops:

920 cc, Mikuni single carb, electronic ignition, 2 into 2 pipes with Supertrapp 3m race mufflers, belt primary, modern suspension, brakes and 17" wheels etc, etc, etc. Wheel base has been shortened via a shortened swingarm and with the oil where it is at present a substantial amount of weight up high over the rear wheel.

Is there actually enough space under a Commando motor to position a tank without hindering cornering clearance or ground clearance over road irregularities, dead kangaroos, next door's cat and that sort of thing ?

There is if you run Commando 750 "S" or "SS" style exhaust system as I have. And who cares if you run over next door's cat anyway.javascript:emoticon(':twisted:')
Twisted Evil

Oil in frame is very do-able. Internal baffling is probably a good idea but watch out because the short cross tube where the rear subframe tapers under the seat nose is actually one length that goes right through the spine so getting up inside is not that easy.

Do u really think it will need to be baffled. I doubt it if the tube only hold approximately 3 US Quarts as I'll just run it with approximately that in it and set up a catch bottle for breathing as well as improve crankcase breathing in conjunction with the new oil reservior system
 

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norbsa48503 said:
Perhaps one of the owners of a early Dreer Norton could do a show and tell on the oil set up. I know your out there.

Looking for me??
The tell part is easy, the show part?????
Internet pictures and me don't seem to work very well. Jerry's still waiting for the shots to post on his Website.

A fill spigot has been added just below the neck on top of the main tube. This causes a special tank to be fabbed as the petro filler would be in the way on a modified tank. The return feed line has been attached to the bottom of the main tube in this area.

A box section has been added under the main tube in the battery box area. This is were the drain and the feed line are, giving less height clearance in battery box.

What's of more interest to me is the breather configuration. He has blocked off the the large 850 breather spigot and created two. I haven't measured them but I will guess 1/4 and 3/8.
The 1/4 feeds the oil back bone just below the filler neck to pressurize it, the 3/8 feeds to the underside of the intake cover at the head. A fittiing has been added to the intake cover to release the pressure and from there it feeds to a breathable puke box, specially fabbed in the triangulated shape of the oil tank, but much thinner, about 1/2. The side cover attaches the puke box, just like stock. An oil cooler sits behind it which is between the battery box and the puke box.

Single shock??? As in central monoshock or single sided shock?

Someone asked if anyone has added an electric start to a Mk IIa?
Yes, Kenny Dreer. Mine doesn't have this but I have seen it.
It is a Harley starter sitting in the Harley position which requires machining and fab work to the inner primary. Kenny runs a belt so oil tightness is not a concern.

I plan on hooking up with the Ton Up Club in Escondido this Sunday, the 9th. Anyone else going???
 

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MichaelB said:
Internet pictures and me don't seem to work very well. Jerry's still waiting for the shots to post on his Website.


AndyP, MichaelB or any other member who wants to show some photos and who isn't quite sure how to go about it, then contact me by email or PM (click on the email/PM icons below) and I will post them up.
 
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