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John, in the modern age the age of modern fuel (Needle sticking) we are fed on a regular diet of BS. It's up to the individual what to believe, at least until belief becomes heresy! Coming to a place near you soon!

Were the Norton Factory race engines etc not successfully tuned?

How could he get it so wrong? It's the con rods that let go.

For what i is worth:

Max. piston speed at 7000 rpm,

650SS 32.62 ms-1, 99SS 30.05 ms-1, 88SS 26.61 ms-1.

T110,30.05 ms-1, T100 29.32 ms-1.

BHP 650SS 49@6800, 99SS 44@6750, 88SS 36@ 7000

T110 40@6500, T100 32@6500.

Values of about 40 ms-1 are usual safe upper limits for air cooled motorbike engines.

Safe limit in rpm dependson piston weight, con rod strength, valve train acceleration etc.

Previously john_hall1 wrote:

C'mon Chaps, play ball.

Let's have it in IMPERIAL!ow this is where the Short-stroke/Long-stroke dilemma starts to take place, with piston speed, acceleration deceleration forces.

Someone once told me once you go above 4,500fpm, then it's usually curtains, not sure about new engines though.

Anyhow in imperial it's:

4087.9265091863513, feet per minute; 650SS @7,000rpm;

3766.4041994750655,fpm, 99SS

2.858267716535433,fpm 88SS

*3766.4041994750655,fpm T110.

A Eureka Moment?

Now look at that the Triumph T110 a 649cc engine is only doing the same fpm as the 497cc 88SS! Was that because they were a more fragile engine, or did Triumph engineers know something Norton engineers didn't?

Cheers

John H

Shorter stroke=lower piston speed for a given rpm

T110 has 82mm stroke. Mean piston speed at 7000rpm = 3766 ft/min

88 has 72.6 stroke. Mean piston speed = 3335 ft/min.

99 has 82mm same 3766 piston speed as T110

650 has 89mm. Mean speed at 7000rpm = 4088 ft/min

I seem to recall that up to 4500 was generally considered OK for piston speed. Beyond some number close to that, the bore lubrication starts to fail. So all these machines are OK in respect of piston speed.

Thetension forces in the con rod are proportional to the stroke and the piston mass. So at 7000rpm (if the pistons weigh the same - which they do not - quite) the 650 con rod has 25% more stress than the 88. A heavier piston increases that stress a bit more, and small changes in stress cause much bigger changes in fatigue life.

Alloy rods don't sound a brilliant idea - but not nearly as much was known about fatigue in 1949 as it is now so (just possibly) that has some relevance. Steel has about three times that fatigue life of aluminium alloys when it has the same stress - but sadly it is also three times heavier.

"They" being ? And did they also use the S7 gearbox/transmission?

It sees like a very complicated way to make a 500 with even less performance than an ES2 (I've owned both, though not at the same time).

Previously john_hall1 wrote:

...

They even put a Sunbeam S7 engine in a Feather-bed frame!

Just read this in a Triton advert on Evilbay!

"The Norton vertical twin engines had a reliability problem when tuned. At about 7000rpm the piston exceeded the engineering limit for piston speed, so over-revving soon destroyed the engines."

EBay item 263180918130

Any thoughts on this?

Cheers

John H

"They" being ? And did they also use the S7 gearbox/transmission?

It sees like a very complicated way to make a 500 with even less performance than an ES2 (I've owned both, though not at the same time).

Previously john_hall1 wrote:

...

They even put a Sunbeam S7 engine in a Feather-bed frame!

Hello, Now When the first 650 Manxman engine was tested on the dyno ,Doug Hele Ran them for well over there time limits at 9000 rpm to destruction but he found they were safe to run at 9000rpm for long periods of time, and all Norton engines were tested on the dyno before being fitted into its frame this is why we get shop number runningout of chronological order and the Manxman engine was the development from the 500cc racing engines known has the domiraces Doug Hele engineeringdevelopments the rest is now history

yours anna j

Previously anna jeannette Dixon wrote:

Previously Julian Wells wrote:

"They" being ? And did they also use the S7 gearbox/transmission?

It sees like a very complicated way to make a 500 with even less performance than an ES2 (I've owned both, though not at the same time).

Previously john_hall1 wrote:

...

They even put a Sunbeam S7 engine in a Feather-bed frame!

Well the first engine to be fitted in a Norton Featherbed Frame was a 600cc Fiat bolted to a Douglasgearbox and Rex Mc-Candelas raced this bike in the Northwest 200 and won , yours anna j

No he didn't, unless the records are wrong. The only Fiat engine of that size available was a 17 bhp sidevalve water cooled 4 from the Topolino. Had one years and years ago. would not have pulled the skin off of a rice pudding.

Artie Bell won on a Norton in 1947, 1949 and on a featherbed in 1950

No race in 1948.

Previously anna jeannette Dixon wrote:

Previously Julian Wells wrote:

"They" being ? And did they also use the S7 gearbox/transmission?

It sees like a very complicated way to make a 500 with even less performance than an ES2 (I've owned both, though not at the same time).

Previously john_hall1 wrote:

...

They even put a Sunbeam S7 engine in a Feather-bed frame!

Well the first engine to be fitted in a Norton Featherbed Frame was a 600cc Fiat bolted to a Douglasgearbox and Rex Mc-Candelas raced this bike in the Northwest 200 and won , yours anna j

No he didn't, unless the records are wrong. The only Fiat engine of that size available was a 17 bhp sidevalve water cooled 4 from the Topolino. Had one years and years ago. would not have pulled the skin off of a rice pudding.

Artie Bell won on a Norton in 1947, 1949 and on a featherbed in 1950.

I doubt that one would dynotest manxman engines to 9000 rpm. The valve train design would not have allowed it.

Yikes! 39 bhp through the S7 shaft and worm-gear? I'm not surprised it broke.

I'll have to ask for the book as an Xmas present

Meanwhile, given the facilities available to the team, why didn't they abandon everything aft of where the crank exits the case, turn the engine through 90?, and use a Manx primary drive, gearbox, etc., of which there were presumably one or two lying around the works?

The S7/S8 engines have a robust crank (admittedly with only two main bearings), short stroke (70mm x 63.5mm, and an "improvable" OHC head, so a plausible candidate for tuning, given a more suitable (for competition) transmission.

Julian

Previously john_hall1 wrote:

Previously Julian Wells wrote:

"They" being ? And did they also use the S7 gearbox/transmission?

It sees like a very complicated way to make a 500 with even less performance than an ES2 (I've owned both, though not at the same time).

Previously john_hall1 wrote:

...

They even put a Sunbeam S7 engine in an "adapted"* Feather-bed frame!

"They", being; Rex McCandless, Leo Kuzmicki, Charlie Edwards, tested by Geoff Duke who was pole-vaulted off eventually at Mira, as the special work by Kuzmicki on the engine, put 39bhp running on methanol, through the transmission which eventually broke and hit the tarmac resulting in Geoff Duke flying through the air!

"They", were desperate for a Multi-cylinder race bike to challenge the Italian and German threat, Joe Craig had been at AMC before he rejoined Norton after the war and had worked on the rival firms Plumstead Porcupine, during the War years. Some think the difficulties they, (AJS/Matchless) experienced, (and of course it was initially designed for Supercharging) had put him off Muti-cylinder plots!

Page 46,"To make a Better Mousetrap", R.L.Jennings, Biography of Rex McCandless with a picture too of the S7 engined Feather-bed motorcycle!

The book is written by an Irishman, employed as a Draughtsman about mainly other "Ulstermen", Cromie Mc Candless, Artie Bell, Oliver Nelson, Joe Craig, (Himself)! Ernie Lyons from across the border, Freddie Dixon, Rex's mentor; who were there at this time in his life, either in Belfast or with Norton in England or personal friends!

The motorcycle section is set during the 6 year period that Rex McCandless spent working as a Specialist Engineer attached to, but not directly employed by Norton Motors.

ISBN: 9780953462841

Cheers

John H