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Info AJS Stormer roadracers

Discussion in 'Other 250's' started by gregt, May 24, 2021.

  1. gregt

    gregt Well-Known Member Premium Member

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    Now I can post pics again, I'll show you something I built a few years ago.

    A local customer came to me with a 250 Stormer engine unit, a set of CB72/77 forks and an idea.
    He wanted a Stormer roadracer for our local short circuits.
    I researched frames used with those engines - and coincidentally a converted motocrosser came to me for work around the same time. It was said to have Irish roads history, then bought by an aussie on his OE and taken home to I believe Melbourne. Next owner was a Kiwi who bought it off the estate of the aussie. The owner at the time it came to me had again bought it off the estate of the first kiwi owner.
    i had to go through it and finish the part done conversion to a very rare 6 spped Villiers gearbox.
    Which needed new engine mounts as they are different.

    Anyway, i didn't like the stock frame - and none of the period race frames appealed. So I did a "freehand" version of the AJS frame tweaked to suit a roadrace layout.
    The customer came up with a Benelli 650 rear wheel. A pair of girling shocks, a Triumph conical front hub which I finned and ventilated which uses the 68'style TLS backplate and a generic TD/TR secondhand fairing off Trademe. Locally made seat and tank. AJS 2.JPG AJS build.jpg Peter's AJS 003.jpg AJS Finished 001.jpg AJS Finished 002.jpg AJS 2.JPG

    It goes very well indeed. But is seldom seen as he also has a Laverda 1200 racebike I built plus a 7R and 500 Manx....Choices, choices...

    The ugly short tank and odd seat version is the converted one ex Aussie. Posted in case someone recognises it.
     
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  2. Murdo

    Murdo The Good Doctor Staff Member Contributing Member Ride and Events Crew

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    Nicely done, good work. :thumb_ups:
     
  3. gregt

    gregt Well-Known Member Premium Member

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    Well, I've bought the Stormer off the guy I built it for. I've got room here now for one project bike as long as it doesn't involve too much as i've had to sell my machine tools. Plan is to give it the development it didn't get. Stick a skinny kid on it and do 2 or 3 meetings a year. Which is pretty much all I'm up for now.
    It'll all be engine development. It's a nice rolling chassis with as good brakes as possible under our pre 72 rules.
    So : A belt drive primary is under way. Farmed out to a local gear cutting firm. I've supplied a clutch drum split out of a spare clutch sprocket assembly. They need to work out teeth numbers to suit the fixed distance between crank and box. It'll also have to be a urethane belt as it will have to run in oil. Crank has an outrigger bearing and the clutch bearing - both are lubed from the primary case.
    Rod and pin will be YZ Yamaha. Spare crank currently being converted. Balance will be by external flywheel. I don't use the existing flywheel for ignition, that's triggered via a Pertronix setup on the crank end. So a small steel flywheel will go on in the place of the OE ignition - and be drilled appropriately for 60% balance factor. I've used exterior balance previously on a Villiers special and it works fine. No probs finding room for tungsten slugs in small flywheels.
    Piston : Suzuki RM250. Wiseco old stock.
    Barrel : #1 motor will use the late Stormer barrel with porting numbers advanced to where they should be.Auxiliary B ports same as TD1C Yamaha. And reed valved.
    I already have a Vforce reed block and need to make up a bolt-on reed valve box. Can't do that till I know where the inlet port is going to finish up.
    Carb : 38mm VM Mikuni
    Pipe : Already worked out but until i can mock everything up it can't be built.

    Spare motor : I have a good OE crank and rod. I have an early Starmaker barrel and have ordered an OE piston. This one will be ported and also reed valved. But with a Yamaha 4 petal I've got lying around here - and the OE 30mm Amal Mk2. And probably the OE pipe. A mid-range motor - a quick motocrosser.

    The differences between early and late barrels are interesting. Early one has very wide inlet with a divider - it's the type which I think originally had 2 carbs - and a single oval exhaust port.
    The late one has a much narrower inlet with no divider. Exhaust port on the other hand is much wider and has a divider.
    Bit better transfers too. Someone had a rethink and said "weve got it round the wrong way"

    Both engines will use the same bolt-on box. A close ratio 4 speed.

    Pic of the simple ignition setup
     

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  4. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Greg are you Murdo's brother by another mother and are you both somehow related to Burt Monroe by a long distant relative?
     
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  5. gregt

    gregt Well-Known Member Premium Member

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    No and No. I suspect I'm old enough to be Murdo's dad though.
     
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  6. gregt

    gregt Well-Known Member Premium Member

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    This is one of the guys I can ask for opinions. Pensioner who lives around the corner from me these days. Looked after mainly American riders but tuned and engineered for a couple of aussies too. I met him when he was riding a Greeves - which tried to kill him at least once. Virtual chocolate fish for the correct name.
     

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  7. gregt

    gregt Well-Known Member Premium Member

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    I suppose I'd better tell you who that is. Surprised no-one answered. It's Mike Sinclair. Yes he lives lierally around the corner from me now. Known him since 1969. Always good to catch up when he came back from the GP wars.
    Worked for Brit Suzuki teams, Kenny Roberts and works Yamaha.
     
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  8. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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  9. gregt

    gregt Well-Known Member Premium Member

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    In fairness, Mike's aged a bit since that article. Also I've never seen a pic of him quite that happy. He really liked the AJS.

    While waiting for major bits - the belt drive, a crank with the good bits and some parts from the UK - I've been sorting through the heap of corroded engine parts....I'm going to get a lot vapor blasted. Set of cases and timing side seal holder, the barrel for the spare engine and when it come back from having a broken fin fixed, the head for the spare too.
    Basically the plan is to not touch the existing good bottom end. Just put the ported old style barrel and head on it and it's done as the spare.
    The cases I'm having blasted will be the #1 engine. They're early ones so will have to be machined to accept the wider crank.
    It's being done to the width of the late ones - which are 2mm wider due to having thrust washers in the big end.
    They're pretty simple vertically split half cases and are thick enough to take the extra width. As the mains are lipped rollers I'd assume the bearing recesses will have to be machined too. Again, it's simple stuff on a lathe.
    I have a full set of new bearings - 2 lipped rollers and a torrington needle roller outrigger bearing on the drive side. All imperial as you'd expect - and not cheap either. Amusingly the bearing supplier said I'd had a pair of the rollers before. Yeah, for a 1935 Rudge I rebuilt. Once the poms find something that works, they keep using it....
    i picked up the good barrel today. I've had the bottom of the exhaust port filled in. The port centerline is going to go up but the existing port floor simply dropped off the liner horribly. Current good ex port shapes are a venturi with carefully shaped bottom curve. this will help me get it to the shape I need.
     
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  10. gregt

    gregt Well-Known Member Premium Member

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    Well, part of the plan hasn't survived. Went to check how the belt drive conversion was coming. It hasn't moved. So took it back.
    Currently investigating getting better quality primary chain from the UK. What i've still to do will take most of this winter at my speed - and I want to run it early December. Trying to get the load of vaporblasting away this week. When that lot comes back I'll do some pics.
     
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  11. gregt

    gregt Well-Known Member Premium Member

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    Still held up waiting for the crank for the good engine. So buttoned up the spare. Early Starmaker head and barrel. Heavily ported. New OE .010in over piston. On the late Stormer bottom end which is still in good nick from when I went through it 15 or so years back. This is as good as i can get using OE parts. Built in the hope I'll never have to use it.
    Both engines will share : Ignition, primary drive and clutch, gearbox and a 38mm Mikuni carb.
    No chance to have the good engine done for the Southern Classic at the end of November so the BEARS Sound of Thunder
    meeting at the end of February is now the tentative target.
     

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  12. KiwiMat

    KiwiMat Well-Known Member

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    Screenshot_20231101_192109_Gallery.jpg i have a RD125LC race bike i need to finish that would look awesome with those fairings, where would a get a set of those?
     
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  13. gregt

    gregt Well-Known Member Premium Member

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    The orange fairing is a generic Yamaha TD/TR 250/350 one bought secondhand off trademe NZ. There are still people making them for classic, post classic and restorations both in NZ and Oz. In NZ a mate in Invercargill Dave Morris advertises regularly on Trademe. I'm sure if you look in the right places there's someone in Oz.
    What you may want to look at is the TA125 Yamaha production racer fairing. It's smaller than the 250/350 one and may suit your frame better. If I was you, I'd go to a Classic/Post classic race meeting with a tape measure and see what suits best.
    The critical measurement from the frame is height of the bars to underside of the frame. Comparing that to the two types of fairing will tell you which will fit best. Remember, the fairings are made to suit clipons too.
     
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  14. gregt

    gregt Well-Known Member Premium Member

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    Took the crank off the guy who was going to do it. Huge backlog of work as he's not been well. Took it to another long time machining source who undertook to get it done before Xmas.
    And he did. Not cheap or an easy job. Yamaha YZ250 rod and pin into the OE early Villiers Starmaker crank. New bearings and seals to go in over Xmas. Very pleased to find no case machining needed. It was always a possibility as I had the crank done to the overall width of the late Stormer one and i didn't know if the early cases would have the room without machining.
    I'd doubt if it'll be done for the Sound of Thunder at the end of Feb. Maybe on track before the end of summer.
    Still a shitload to do. Rod is longer so there's a barrel spacer to make plus porting to do.
     

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