Proposed re-build

Bought my first Norton in June of '76. It was the last black and gold MKIII in the Duarte Ca. warehouse. Been a Norton guy since. I'm primarily a road riding guy on the Norton but I have 46 years of Trials riding experience. I've never raced. Don't know anything about racing. Been reading the posts here for about a year and joined. I freely admit that most of the technical "racing" stuff is a bit over my head. If I keep reading everything, sooner or later, some of it will soak in. I'm getting ready to do my first complete re-build on a '75 and have a few questions. I'm sure you've heard the saying "I know just enough to be dangerous". Well, I know just a little bit more than that, barely. I was in the INOA for 20 years and spent a lot of time at British Marketing when it was run by Brian Slark.

1) Basically, I'm on the outside looking in and have no idea where to get "good" pistons or "proper" Norton head work done etc. I would like to see a column on the website for "Services", with phone #s or email addresses so that those of us that are new to high performance can find out where to go or who to contact.

2) I've seen on this website and ebay , pushrods, rocker arms and con rods that were polished and the posting made a big deal about it. Other than reducing the inherent stresses in the metal or aiding oil dispersal/flow what is the purpose of polishing these parts?

3) When I re-build my bike I'm going to have it balanced, con rods polished or shot-peened, and have the head re-worked, shaved, ported, polished and perhaps re-angle the valves. I'm thinking of changing it from an 850 to a 750 for added performance, unless someone can convince me that an 850 can be as quick as a 750 with proper head work. Haven't looked yet, but would consider keeping it an 850 if I have an RH 10 head. I know that I'm never going to beat a Jap bike, but I would like to stay in his rearview mirrors a little longer. Being beat off the line by a station wagon is a little embarrassing (the MK III is a slug). Again, I'm not a racer, nor am I going to race the bike. I shift at red-line and rarely go over 70 mph. I'm also planning on a Combat cam (have it already) and dual Keihin flat-slide pumper carbs from CNW.

4) Norton race trannys are all right side shift. I'd like to put a 5-speed in the bike. Does anyone make 5-speed gears that would be inter-changeable with the existing (left side shift) gear box? Who?

5) I bought a set of cam followers (lifters) at a All British Swap Meet that are radiused. I was told that the work was done by Ron Wood, a Norton racer back in the day. What is the purpose of the radiused lifters. They shorten the valve duration, I know, and it's my guess that that they are "race specific" for sustained periods of very high rpm. If I don't need them in my street bike, please let me know and I'll sell them on ebay. These lifters are nearly fully round, he didn't just ease the corners. Quite good looking actually.

6) What pistons do you advise?

7) Hoping for CNW brakes, hydraulic clutch, front fender, chain guard, their drive chain conversion (maybe) and a paint job by them.

What I'm hoping for here is a star to steer by and a general direction to go to avoid buying duplicate parts. I've been slowly collecting the parts for it that I'm going to want and I'm not even going to start the dis-assembly until I have all of the parts that I need. I don't expect to finish for two years, so I want to do a nice job. I want it to be very nice looking. I'm not one of those guys that can say money is no object, it is, hence the two year time frame.

Thank you for your input and ideas,

Clyde

Lotta info sought. Were you considering doing the engine build yourself? Or have an accomplished master do it for you? How much money do you have to spend? Can you post us pics of the original?

Definitely something wrong if your MK111 850 is a slug. I have one with nothing more than open peashooters and a 20 thou head gasket. It surprises me for power every time I ride it, even after getting off a 160 HP Triumph Triple.
Not that it can stay with the triple, but because of the 850 Norton grunt, it has every bit as much power as the Triumph to about 6 k rpm.
I can't really comment about power upgrades, except to say that just reducing the displacement will not be a power upgrade. These bikes are torquesters, not big horsepower machines.
The book says 48 ft lbs torque for a 750, 49 for a Combat and 56 for 850s , including the MK3.

tall951guy said:

What I'm hoping for here is a star to steer by and a general direction to go to avoid buying duplicate parts. I've been slowly collecting the parts for it that I'm going to want and I'm not even going to start the dis-assembly until I have all of the parts that I need. I don't expect to finish for two years, so I want to do a nice job. I want it to be very nice looking. I'm not one of those guys that can say money is no object, it is, hence the two year time frame.

Thank you for your input and ideas,

Clyde

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Hello Clyde,

MK3's are pulling good money. Sell it, buy a nice Combat with cash left over and don't miss 2 years riding.

2nd this >

MK3's are pulling good money. Sell it, buy a nice Combat with cash left over and don't miss 2 years riding.

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and pull even better after 6grand and no fragile Spragthrope designed parts either.

Maybe you can even swap someone for a nice non ES 850.

To actually answer a few of those questions:

tall951guy said:

1) Basically, I'm on the outside looking in and have no idea where to get "good" pistons or "proper" Norton head work done etc. I would like to see a column on the website for "Services", with phone #s or email addresses so that those of us that are new to high performance can find out where to go or who to contact.

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There are a TON of shops that can do this kind of work, and often if you find a competent local machine shop, they'll do whatever you ask as long as their tooling is good enough. I got all my work done at a local shop that uses all rottler equipment that's top notch. Ask for a tolerance and ye shall receive. For porting and other work, you're going to want to send it out, and I can't give you any advice on that. Other than that, most of the work is not rocket science to do (from grinding a crank, to resurfacing lifters...etc...)

tall951guy said:

2) I've seen on this website and ebay , pushrods, rocker arms and con rods that were polished and the posting made a big deal about it. Other than reducing the inherent stresses in the metal or aiding oil dispersal/flow what is the purpose of polishing these parts?

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Reduce stress risers from machining marks and others to increase the fatigue life of the part. Helps keeps things going longer and lower the chance of fatigue/fracture when running.

tall951guy said:

5) I bought a set of cam followers (lifters) at a All British Swap Meet that are radiused. I was told that the work was done by Ron Wood, a Norton racer back in the day. What is the purpose of the radiused lifters. They shorten the valve duration, I know, and it's my guess that that they are "race specific" for sustained periods of very high rpm. If I don't need them in my street bike, please let me know and I'll sell them on ebay. These lifters are nearly fully round, he didn't just ease the corners. Quite good looking actually.

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Will end up affecting the duration of the cams and effectively change the profile of the cam. Probably not a wise choice to run on the street.

In my opinion, you're in for a LOT of money with what you've described. I imagine that this is the sort of time you'd want to sit down and think about what you want in the end, and find the right bike to start with to save you time/money. If you plan on swapping motors/frames, find a cheap motorless frame and a cheap frameless motor and combine the two instead of starting with a matching pair that has value for that, etc...

Just my $0.02

Theres no replacement for desplacement . :? unless its turbos & rpm's .

Hemisphered Head & youd end up with a long stroke short stroke P. R. Head . Tourque x RPM's = boogie .

I know that I'm never going to beat a Jap bike

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CALL THAT A POSITIVE OUTLOOK .

I'd%20like%20to%20put%20a%205-speed%20in%20the%20bike All 5 speeds are 1:1 top , direct , as per 4 speed .
most are close ratio , so firsts no lower - when you gear it 24 T for 140 mph @ 7.000 .
Ideally :? youd have slightly closer gears with a lower first , so on tall gearing 1st is not a lot higher than std .
Need to do overall ratio tables to figure these . there SIX Speed Trans Avail too .

You can end up with nothing but the Clocks Left . :shock: And THEYRE best Raplaced . :twisted:

These were the Gung Ho F-750 item in the day , 1970s . Impulse means its instantaeneous accurate mapping .
Lag in old magnetic things can be a few hundred RPMs easilly . Hence CHRONOMETRIC Tachs superior .


All that power and the chassis is going to show its age , therefore a Egli or Rickman or Seely might be a good start .


The MANEY (and other - CASES , cranks , alloy barrells , FullAuto Head , & a new primary / Clutch & youd
still have the Standard Grease Nipples . If you bought new ones youd still have TWO BIKES .

A bloke here got a neat M-X tyred ( knobblies ) Roadster , or use the supermotard stuff , then just suspension
and you wont need all this Hi Po super tune tripe .

Electronic Ignition could be regarded as mandatory in any case . Raceing is cubic dollars .
No Harm in a 850 Combat , Mr poores dream . But those nasty regulatory rule makers thought we'll have no rowdy
obstroperous motosickles . good mufflers carbs & porting with it all glued together properly would do it .

POolishing Shot Peeded rods reduces drag and reduces chances of surface flaws , wich could spread .

OR



:shock: :mrgreen:

If you're not going to race the bike then why go for all of this "High Zoot" stuff? The Commando is plenty fast as it comes from the factory. Do a sensible rebuild and enjoy your bike. If your bike is sluggish something is very wrong. I just recently finished a ground up build on a basket case Norton,and she runs great. Tons of torque and more speed than I'll ever use. My bike is a 72 750 noncombat and fast enough for me......Skip

Any good running Norton should keep up with a new Mini S. Look at the numbers. But like the Eastern bikes, it'll out run you in the end. If a station wagon beat you, there's something wrong with the bike or your driving method.

As far as all the other mods, like others have said expect to spend 20-30 grand or more. Might as well have CNW build you a custom one and wait a couple years.

But it's a nice thought experiment.

Matt Spencer said:

OR

:shock: :mrgreen:

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I'll take one, please.

DogT said:

Any good running Norton should keep up with a new Mini S. Look at the numbers. But like the Eastern bikes, it'll out run you in the end. If a station wagon beat you, there's something wrong with the bike or your driving method.

As far as all the other mods, like others have said expect to spend 20-30 grand or more. Might as well have CNW build you a custom one and wait a couple years.

But it's a nice thought experiment.

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With that bad a performance I'd want to put a dial gauge on the rocker arms to see if the cams have worn down. Not uncommon occurance.
However I'd confirm ignition timing first.

Well you could go with the JS pistons and long rods as well as his cam/follower, pushrod and valve setup then you just need to get it ballanced. It seems like the hard bit is finding someone who knows what they are doing to sort out the porting. Then chuck on one of Jims reed valve breathers. Once you have done that you probably should put in some Cosentino cartridges in the forks too.

http://www.jsmotorsport.com/
http://www.cosentinoengineering.com/ind ... age405.htm

Thanks everyone for your replies:

Perhaps I exaggerated a bit on the poor performance of the MK III. I've owned four of them and one was punched-out to 940 by George Jonavich at HPI (circa 1980). I've also owned a '74 850, a '71 750, a '72 Combat 750 and a '72 non-Combat 750. All of the 750's and the 74 were quicker than any of the MK III's, including the 940 and including my original MK III which had an Axtell cam, shaved head, balanced crank and an exhaust. It was tuned by AMA Hall of Famer Brian Slark. Also, I have to admit that these bikes were a lot more fun to ride than the MK III's. But! I never felt safe or comfortable with the rear brake pedal on the left side. So it's a MK III for me (you can't teach a old dog new tricks). Personally, I don't give a dead rats corpse about the electric start and will be removing it along with the relay and sprag etc. I want the rear disc though. Now, if the MK III performed as well as a Combat I wouldn't change any thing. It doesn't. Mine will when I'm done.

I will post photos when I finish. But I'm not going to take it apart until I have everything so that I can ride it longer.

"concours" Except for the machining and painting I will be doing all of the work myself. I hope to keep the cost at about $10,000 not including the price of the bike nor the $2,000 in parts that I have already.

"midlight lamp" Aha! That is what I thought about polishing the rockers etc. As for the radiused lifters, I'll be putting the up for sale on ebay today or tomorrow. Thank you for the info.

Thank you all again,

Clyde