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72 AJS Norton Stormer

Re: 72 AJS Norton Stormer

Postby frankdamp » Mon Aug 08, 2011 7:17 pm

For the two seasons I was there, we raced the 250 and a "360" so we could race in the "over 350" class. Nobody ever checked, but the "360" was actually only 345 ccs!

The bigger capacity engines were real problem items, I understand, (I'd emigrated before they came along) because the cylinder liners got very thin and the bored-out crankcases weren't very stong. I suspect that the fuel/air charge into the cylinder, from what was basically a 250 crankcase, may have seriously limited the power of the big engine.
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1967-68

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Re: 72 AJS Norton Stormer

Postby Cheesy » Wed Aug 10, 2011 2:46 pm

swooshdave wrote:
frankdamp wrote:I spent the last 8 months of my N-V career working on the Stormer program. Two things to watch for, if they hadn't been fixed in your model year are problems with localized overheating which damages the cylinder liner and frame cracking inmmediately aft of the headstock stiffener (if yours doesn't have the tapered top tube). Taking a closer look at your full-bike photo, what appears to be a weld line along the center of the top tube suggests you have the tapered set-up. Your bike is dated four years after I left for America. The "new" ones being built in a chcken shed were built by one of the retired Moto-cross mechanics from parts he'd bought when the company went broke. if you go to the AJS Owners news group there's some info on him.

The engine overheat was a part-throttle detonation issue. The Starmaker woud run WOT for days without complaint, but in stop & go, light throttle settings, the liner would get red hot around the area of the exhaust port and you'd get instantanous welding of the top piston ring as it passed by. This would set up an oscillation as the piston travelled on and circumferntial ripples would develop. Initially, we would see this in less than 1000 miles on a new liner. I tested the bike riding to and from work on one that had lights.

Initially the fix was to use Castrol "R" in the fuel, but it doesn't dissolve in gasoline, being a vegetable-based oil. After about 6 hours of not being run, you had to give the bike a good shaking to re-mix the gas and oil. As I left (June '68) they were working on a more user-friendly fix.

The early M-X bikes had frequent frame failures caused by a stress raiser where the original design of heastock reinforcement ended. I propsed splitting the top tube into two semi-circular pieces and welding a long triangular piece of flat steel in between on each side. the resulting top tube went from being an obround cross-section almost the full depth of the headstock down to the original circular section at the back. I think this made it into production.

One of the cleverest bits of design on the bike was the eccentric plate for chain adjustment, It shows very well in your pic of the gearbox. I've since seen an identical set-up on (I think) a KTM, so maybe the AJS design was sold off when N-V went Tango Uniform.


I was waiting for you to chime in with your experiences.

I'm sure with a modern two-stroke oil like Royal Purple the overheating issue should be minimized.

Didn't they also use the eccentric adjuster on the B50?



I wouldnt bet on new oils being better, I did my masters thesis on two stroke engine liner/ring/oil wear systems, one of the interesting side outcomes I came across was that the Castrol A747 (cant remember exactly what it was called) had the best scuff resistance of any of the oils I tried over a range of ring and liner materials, this included some rather expensive synthetic 'race' oils. That said scuff resistance is only one aspect of it.
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Re: 72 AJS Norton Stormer

Postby Carbonfibre » Thu Aug 11, 2011 12:27 am

A747 is a synthetic/castor blend. 747 has now been superseded by XR77 which is a fully synthetic oil, which among other advantages provides accurate plug colour readings, when modern fuels are being used.

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Re: 72 AJS Norton Stormer

Postby Rohan » Thu Aug 11, 2011 7:53 pm

Cheesy wrote:
I wouldnt bet on new oils being better,


I would. Engine seizure in GP125 and GP250 racing is almost unknown these days - although the engines are watercooled. And producing beyond 400 bhp/litre.

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Re: 72 AJS Norton Stormer

Postby Cheesy » Fri Aug 12, 2011 2:08 pm

Rohan wrote:
Cheesy wrote:
I wouldnt bet on new oils being better,


I would. Engine seizure in GP125 and GP250 racing is almost unknown these days - although the engines are watercooled. And producing beyond 400 bhp/litre.


They also wont be using cast iron liners or chrome plated rings either..... There are a lot of variables involved, of the oils I tested the A747 had the best scuff resistance, I cant remember what all the other brands were off the top of my head though. Of the rest of the oils the ones that were TWC3 rated oils were the worst, the rest had different rankings for different ring/liner material combinations, the ranking wasnt of scuff resistance but the wear rate of the seals and the liner material. When a particular material couple and oil did scuff it was a surprisingly repeatable test.

Also when I say liner it is really a plasma sprayed coating that is applied directly to the cylinder wall and then ground, the ring materials were generaly PVD coatings on nitrided SS rings, almost all of these materials had wear rates that were orders of magnitude better than cast iron and chrome.

I hadnt remembered that the A747 was a synthetic blend either, I thought it was older than that as it had already been discontinued before I tested it so you are right about newer oils being generally better.
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Re: 72 AJS Norton Stormer

Postby ajstormer » Tue Apr 09, 2013 11:00 am

i have recently bought an ajs stormer 410 - road registered

to add to my other off roadie (yam it465)

i found the information about the stormer very interesting !

Image

Image

Image

the small end bearing on the con rod is plain metal - so you need to use castor oil - or you will

get premature wear on the small end. Also none of the parts are ethanol resistant. So the tank needs to be

drained after use......

It handles well - but the engine is so tempremental - dont stall it , it will NOT hot start

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Re: 72 AJS Norton Stormer

Postby Rohan » Tue Apr 09, 2013 2:41 pm

ajstormer wrote:It handles well - but the engine is so tempremental - dont stall it , it will NOT hot start


Even if you give it full throttle when you kick it ?

If you want to read up on the earlier history of the Stormer, its probably worth commenting that the earlier James are related - as the NVT empire was crumbling, the Motocross/Scrambles side of things was renamed to AJS. Probably a bit of Francis Barnett in there too somewhere, since that was part of the AMC stable as well, and they were keen dirt guys...

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Re: 72 AJS Norton Stormer

Postby ajstormer » Wed Apr 10, 2013 2:41 am

thanks for the info..... :D

i am rebuilding the engine at the moment

points and magneto's dont work

Image

rusty , worn and neglected

Image

i have purchased a modern CDI - from electrexworld

Image

looks well made - but they offer a lighting kit - that will be available 'next week' , from last september !

Typical British engineering companies.....tomorrow never arrives....

Anyway i was fortunate that i looked at the magneto because both mains bearings were out of spec

slightly more play than even the designer was prepared to accept. Spares are available . NOS that have been

getting rusty in forty years of storage......

http://www.ajs-shop.co.uk/acatalog/PIST ... RINGS.html

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Re: 72 AJS Norton Stormer

Postby frankdamp » Wed Apr 10, 2013 3:29 pm

The engines were "pure-bred" Villiers. The first Starmaker, a 250, was used in a road-racing bike built specifically for the program just before Villiers was merged with AMC. My old boss, Peter Inchley, rode it in a number of events in 1965 and 66, ending with the 66 TT. He was running second at the final pit stop for fuel. He gassed up and took off again only to have the engine seize up about 5 miles down the road.

The team in the next pit also had an engine failure with much blue smoke and fouled plugs. I understood, from the stories I heard around the office when I joined N-V later that year, that the TT's fuel supplier delivered the 2-stroke mix to the next-door pit, who were running a 4-stroke, and the Villiers pit got gas without the oil.

There was one interesting artifact in the competition shop when I started there. A grid made up from masking tape was mounted on the wall, with inch markings from a felt-tip pen. I asked what it was, and Pete's assistant produced some photographs. They showed the 250 TT bike on an axle stand with Pete on the seat in a racing crouch. One of the pictures had a hand-drawn fairing on top of the image.

Apparently, they took side and front views, drew a fairing shape in, then produced some engineering drawings of the shape and had a local fiberglass firm make a fairing. "Wind tunnel? We don't need some stinking wind tunnel!" Pete commented that at one point coming downhill on the TT course, he was in a full crouch and going just about as fast as 250 ccs can get you going. He sat up to see the next corner a bit better and got another 5 mph top speed.

The motor in the Stormer series descended directly from the Starmaker. I think the "detuning" from its full throttle race settings caused the part-throttle detonation problem. Since I'd left before it grew beyond the 350cc size, I'm assuming that the crankcases and cylinder liner were substantially redesigned, otherwise the liner would only have been a few thousandths of an inch thick where it went into the case.
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Re: 72 AJS Norton Stormer

Postby Rohan » Wed Apr 10, 2013 5:45 pm

James and Francis Barnett had been using the Starmaker (and other) Villiers engine for years before 1965.
The AJS Stormer was a James with the badge changed.
And the James, in turn, was basically a Francis Barnett designed chassis , painted in a different colour !

If you have a squiz at old scrambles pics, you can find basically the same bike badged as Francis Barnett, then James then AJS.
With some evolution - almost entirely from the Francis Barnett side of things...

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Re: 72 AJS Norton Stormer

Postby frankdamp » Wed Apr 10, 2013 7:46 pm

I believe, Rohan, that the Starmaker was a newly designed engine in late 1965. It had some obvious relationships to the older Villiers designs, particularly the 197cc "9E" - I think some of the castings might have been very similar. Until the N-V conglomerate was formed, Villiers sold many thousands of engines and transmissions to the UK manufacturers of "beginner" bikes, like James, Francis Barnett, DOT and also quite a lot of higher performance engines to Greeves. They also sold the 2T, a 250cc two-stroke twin, to quite a lot of their customers.

I agree with your comment about James and F-B being "badge engineered" and they used a lot of Villiers engines and transmissions, but I'm sure the Starmaker wasn't one of them. The 250 most other manufacturers bought from Viiliers was the 2T. The Stormer frame is very much based on the Commando, and was a Wolverhampton design by Bob Trigg's engineering people. The only real difference is that the top tube joins the headstock towards the bottom instead of the top and of course, no Isolastics. Some time ago, there was a photo on this forum of the fatigue crack in the unmodified Commando frame. One of the works M-X bikes had an almost identical failure, on the top side of the top tube - since the gusset was the opposite way round.

Also, immediately prior to the formation of N-V, I understand that Villiers was considering getting into bike manufature. They were doing quite well selling engines and transmissions, also building cylinder heads for the high performance version of the Ford Cortina (the Lotus dohc version) under contract to Lotus and Ford. Unfortuinately, neither they nor the rest of the small bike makers saw the Hondas coming - twice the power, electric start, four-strokes and much more sophisticated machines than what Villiers' customers were making.

If the N-V consolidation hadn't happened, there may have been bikes out there with "Villiers" on the tank and they'd have gone to the wall much sooner than N-V eventually did.

Until the formation of N-V by Manganese Bronze Holdings, I don't think Villiers had any interest in, or connection with the James and F-B bikes, other than being the supplier of their engines and transmissions. Since I only worked there for a very hectic 16 months, I might have mis-interpreted some of the things I heard.
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Develpment & Competition Department
1967-68

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Re: 72 AJS Norton Stormer

Postby Rohan » Wed Apr 10, 2013 8:26 pm

There may have been more than one version of the Starmaker then ?
At some point, the twin carb version became a single carb ?
Some cylinders look more slanted forward than others ?

Don Morleys' excellent book on Classic British Scramblers quotes that the AMC-made 2 stroke engines were a flop, and "for 1963 both James and FB fitted either the twin carb Villiers Starmaker or the Villiers 36A engine with Parkinson all-alloy top end". Also shows a pic of Chris Horsfield in action on a James, with Villiers Starmaker engine.

He mentions quite a lot of the history of FB, James and then AJS, and how they and the team riders were all blended together eventually into the AJS Stormer, mentions Peter Inchley at AJS.

And also that in 1972, the Stormer got a Cotton frame, and the James connection was gone..

Cheers.

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Re: 72 AJS Norton Stormer

Postby ajstormer » Thu Apr 11, 2013 5:14 am

very interesting info....thanks

i think the stormer (and starmaker) engine stayed pretty much the same- small changes to clutch

they just tilted it in the frame.....

1965
Image
1970ish
Image
1977
Image

they kept making them until they ran out of engines.!

from what i understand the frame was originaly a Fluff Brown design for Cotton motorcycles, which he
continued to develop when he was competition manager at AJS.

I have seen a picture of a Cotton with the starmaker engine and the frame 'looks' the same in 1962 ish.
Predating the commando by some years.....

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Re: 72 AJS Norton Stormer

Postby frankdamp » Fri Apr 12, 2013 9:33 am

The frame in the Sprite photo isn't the AJS frame. It has a triangulated top tube design. Also the loop behind the gearbox is a different shape.

Incidentally, the tail-pipe extension/spark arrestor/muffler on your Stormer is about identical to the ones N-V made for the 68 ISDT bikes. We entered three 250's that carried the AJS badges and one 350 that carried a Matchless badge. I'm pretty sure that was way after the last of the AMC Matchlesses and probably the only ever two stroke to carry the badge.

The bikes were ridden in the event by four guys from the Royal Air Force Motoring Association.
Frank Damp
ex-Norton Villiers - Marston Road
Develpment & Competition Department
1967-68

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Re: 72 AJS Norton Stormer

Postby Rohan » Fri Apr 12, 2013 2:34 pm

frankdamp wrote:The frame in the Sprite photo isn't the AJS frame.


Thats because it is a Sprite frame !
Supplied, in kit form, by Sprite Motorcycles, Oldbury, Staffs.
Add your own engine - including the Starmaker.

Apparently they (briefly) sold hundreds of them in the mid-1960s, at the then 'bargain' price of 154 quid.
just like Don and Roy Jordan were winning on.
The tax loophole that allowed this was soon closed, and the bubble was over...

Info from Don Morleys book on Classic Bristish Scramblers.
Excellent book, the depth of research is amazing...

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