What would you chose for rebuilding ?

Hi Xavier, on the ebay link ,it's a MK3 bottom end , so you will have problem to fit (possible , but....), your primary case,if money is not a problem , go for maney , but why go 1007 ? stay in 850 (my opinion) , or if you are not in a hurry , wait and check ebay (though the prices are going crazy on this way) , or why not put an add on that forum? but take it easy , as we always make mistake when we rush (yes I am old , now!).

I Forgot the primary case fitting ! Thx Pierre

hobot said:

...go light everywhere ya can. The lighter pistons/rods also tend to make crank act more massive.
If even more right now response desired get the flywheel OD trimmed back 1/2".
Think about programmable optic triggered PwerArc ignitions.

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So light it is ! But I'll wait for the Optic Triggered Ignition, otherwise that's my wallet that's gonna be too light
I want a strong basis, so I can upgrade gradually later without changing everything again

I don't understand the caution of using Maney and other hi end components requiring special equipment to assemble and run as they are made extra heavy duty with care in fit and finish for racing endurance. Lightness is Rightness and if my targets were not deer and sports bikes in the way when blower on boost I'd go with my ole welded up Combat cases with a 850-920 Maney barrel and Fullauto head and Norris D can with BSA lifter and put the crankcase savings in a ITT gearbox as Norton drive train is the weakest component to stifle the power hit joys. There's like 6 lb excess mass in all the steel spacers of a Commando wheels to steering stem and frame attachments. Don't need steel foot pegs or linkages either. Many places to save a few oz of rotating and recipercating mass that become rather more massive in motion. We all Love spending others money on this.

ludwig said:

Bonjour Xavier ,
I'll be in Aquitaine next week .
If it is ok with you , I'll pop in .
I will PM my cell phone nr .

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Salut Ludwig,

I'll be passing you in the opposite direction! I promise we'll meet up one day.

Webby

I'll have all the continental experts for me !

And here is what the Brian/webby03 expertise revealed :



Beautiful, isn't it ?

:wink:

Xavier

Here's Ken's thread showing his modifications to the cases for strength.

short-stroke-750-build-t5490.html

What sort of head do you have now? If it is an RH10 that is a good head and I would keep it.

Any well put together Norton heavy twin will keep up with modern traffic cruising at 70mph, even a 500cc, so with today's fuel prices I don't know why anyone would want anything bigger than stock.

If you are talking about reliability I would go with a stock bore. On an 850 try to get your compression to 9:1 and your squish around .035 so it runs good on whatever fuel is out there in hot weather. Whack the head or change the pistons, whatever you have to do.

Get a new set of Andover rods. 850 engine parts pop up on Ebay USA all the time and very often have low miles on them and are in excellent shape. I scrapped out three 850 Nortons and the cranks in all three had std. journals. The stock flywheel makes the bike idle nice and easier to ride in stop and go traffic, and also in high gear against wind gusts.

The JS carrillo rods and light pistons would certainly add to reliability and I think are the No.1 best upgrade to an otherwise stock engine, cutting vibration and putting less stress on every part. The stock 850 cams were often soft, get a brand-name came made from hard material with a grind mild enough to fit in the stock cam tunnel. For the street any other racing parts are a waste of money.

For fuel economy and reliability I would get rid of the original Amal concentrics and get the later Amal square-bodies etc. and of course a Boyer.

Then gear the bike up so it is doing about 3000-3200 rpm at 70mph, that is great for economy and reliability, and oil consumption. People that run around on Nortons at highway speeds screaming them at 3500-4000+ rpm, especially the 89mm stroke jobs, are missing the point.