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Matchless Typhoon

Discussion in 'AJS & Matchless' started by worntorn, Jun 1, 2013.

  1. GRM 450

    GRM 450

    Joined:
    Dec 30, 2008
    Rohan mentioned XT 500 yamaha and I found an old picture of my TT 500.
    I thought it was too heavy for dirt but could be useful as a road /track bike.
    [​IMG]

    Nothing as good as a G50 or Dave's Seeley G50 or other singles you fellows have or had, but it was a good bike in its day and even won a race.

    I tend to like the simplicity of 2 valve air cooled singles.
    And they are the best fun to ride smoothly and shock some modern bikes in tight roads.

    graeme
     
  2. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    GRM,
    There are about four guys who race those bikes in our Period 5 historic class against TZ350 Yamahas, and they go extremely well. However I cannot see why they cannot be permitted to race against the Manx Nortons etc in the pre 1962 class, also there is one Seeley G50 which runs in Period 4 ('63 to '72) against the 1300cc CB750 Hondas and two strokes. A class for air cooled two valve singles and twins up to 500cc would be excellent, and not rocket science to organise. Unfortunately our historics are run by sidecar idiots who don't know where their backsides are. What pisses me off is that it could be so good.
     
  3. Rohan

    Rohan

    Joined:
    Aug 26, 2010
    This is my attempt to build an earlier 'Typhoon' from a kit of parts.
    If you look closely, its based on a 49 AJS road bike. As many were then.
    Photo taken a while back. - it struck a problem when the hepolite piston for the rebored cylinder can't be located,
    moved house a couple of times since then, been waiting for it to resurface. (!)
    May have to have a new one made up, already at +60 so another rebore is not an option.

    [​IMG]

    Noticed this one for sale around the traps, same year, but Matchless.
    Different interpretation.
    Versatile bikes back then...

    [​IMG]
     
  4. Rohan

    Rohan

    Joined:
    Aug 26, 2010
    Note that both these are fitted with a Burman CP gearbox.
    Still intact after 60+ years.

    Although mine at least hasn't done much running lately....
     
  5. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    Rohan, The worst experience I've ever had with a motor was with one of those. In the old days, if you raced a big single it was essential to get a forged piston, preferably a Mahle.
    I was fitting rings to the motor, and being an idiot didn't know about filing the ring gap to get the correct end clearance. The piston was tight when I tried to fit it in the bore with the rings. It went in and went up into the wear area where it stuck fast. I broke the piston getting it out. The piston was an original which was wire wound to stop it from growing - unobtainium except at great expense. I suggest the bore size is too big to use a cast piston, unless you are prepared to age it in an oven, and you still won't know it is not OK until it grabs.
     
  6. Rohan

    Rohan

    Joined:
    Aug 26, 2010
    This motor was VERY well worn when acquired, with wire wound OS piston, so had obviously done a fair old mileage.
    The place that had did the reboring had warned too about making things too tight, and gave it a good clearance.
    Hence my keenness to find the piston bored for it.

    A lot of those piston growing stories seem to come from fitting certain aftermarket pistons.
    Matchless motors were renowned for their quiet running from new, with a wirewound piston.
    I had previously heard one rebuilt by a Matchless old hand, and it just rustled when running, no noise at all.

    So you have entirely answered your own post = "I didn't know".
    Explains some of your comments about AMCs....
    Not removing the top cylinder ridge when fitting new rings is an absolute novice mistake.
    I think I learned/discovered/heard that on a very sad BSA bantam (cheap lesson !?)

    Cheers.
     
  7. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    I simply went to the shop with the cylinder and piston, and asked the guy for rings to fit it. The trouble was that it was all SO EASY to stuff it up ! It wasn't the ridge at the top of the bore, all I did was push the piston up from the bottom, and it stuck fast halfway up the bore. I was about 16 at the time, and had hardly started hotting up those old dungers. A couple of years later it was an entirely different story, we had gotten into addiction to speed. The friend of mine who recently died actually taught me to build a race motor when I was 18 (1959). He'd been heavily involved in racing since the mid fifties, and had a lot of very good but rare engines etc. I was recently told that his mother used to finance his racing - lovely lady !
    If you can find a 500cc Aerial Red Hunter - buy it ! The gears out of a Square Four fit that gearbox, and the motor is basically a JAP.
     
  8. Triton Thrasher

    Triton Thrasher

    Joined:
    Feb 10, 2009
    It's unusual to get a rebore done in absence of a new piston.

    If your borer is advising generous clearance he sounds more au fait with old bikes than many engineers are.

    So far as I can tell, the typical Taiwanese new pistons have the same expansion characteristics as UK-made Hepolites.

    Specs for wire wound original pistons are probably too tight for any piston available now.
     
  9. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    Japanese two stroke pistons are spun cast, then forged to get the grain flow right to stop seizures. I don't believe the British ever used that technique. I used Hepolites in Triumphs, never had problems, but the bore size is relatively small, and the clearances are larger than in any two stroke. Years ago we fitted a Mahle, Jawa two valve piston into an Aerial 500 single. Reshaped the head with a porting tool to get the angled squishband, and left a corner where the head meets the barrel. It was excellent, however we had to find a skinny oil ring to fit it, and machine the bottom ring groove to fit. - Running on methanol at very high compression, so it was cooler than with petrol. The smaller the clearance on the piston skirt the better, providing there is enough to stop it grabbing. Ordinary cast pistons are very suspect. Many years ago there was a particular type sold in Australia which destroyed many engines. I used them in a Triumph 650, and broke the crankshaft when one seized as we thrashed the bike two-up. We rode it home clunking , and when we pulled the motor apart found the shaft was hanging together by 5mm of steel. If I was rebuilding an old British single, I'd look for a Japanese or Ducati piston to suit it, even if I had to shorten the barrel and re-bush the gudgeon pin in the rod. Lighter pistons are very good news.
     
  10. Rohan

    Rohan

    Joined:
    Aug 26, 2010
    He, obviously, had the piston in his hand when this was done - its since gone into hiding.
    The wirewound one, with supertight clearances, was the VERY well worn oversize one in it previously.
     
  11. Rohan

    Rohan

    Joined:
    Aug 26, 2010
    How can a piston both be spun cast AND forged ??
    Where did this info come from
     
  12. Triton Thrasher

    Triton Thrasher

    Joined:
    Feb 10, 2009
    Well, it's obvious now!

    Wonder if a specialist could make wound pistons nowadays.
    I expect they'd see it as introducing stress raisers and extra weight.
     
  13. wakeup

    wakeup

    Joined:
    May 1, 2013
    Rohan said ..."How can a piston both be spun cast AND forged ??"

    Cast a blank, and then forge it maybe?
    cheers
    wakeup
     
  14. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    Rohan, I believe the Japanese use a high volume production machine in which the die accepts molten aluminium while it is spinning, then as the melt cools the other part of the die is impacted to forge the piston. It gives better grain flow which make the piston less likely to expand irregularly. A few years ago, a friend of mine had a racing T500 Cobra racer and said 'if I want pistons, I can always make them'. It is not as simple as that. When Jack Findlay won his first international race on a 500cc Suzuki two stroke, the factory lent him two secondhand pistons, then demanded them back after the race. You will note that Bill Ivy was killed while riding through the pits at low speed with his helmet undone. The bike siezed and chucked him onto his head. The worst thing was that stupid Greeves Silverstone with the big British piston in it - always an accident waiting to happen.
     
  15. Rohan

    Rohan

    Joined:
    Aug 26, 2010
    Sounds like the factory pistons were not like the customer got then.
    How unusual....

    We diverge somewhat from Typhoons ere...
     
  16. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    I think what the customer got depended on the year of manufacture. Findlay's win was one of the first for 500cc Suzukis. Like all that stuff, if you were a factory and had the edge, would you let everybody have the same advantage ? The Japanese weren't too bad in that way, - privateers were probably only a year behind. I've seen some exotic stuff in ex-works manxes. My friend still has an ex Jack Ahearn 350 manx - good stuff. Have you seen the double knocker rigid frame model in this months Motorcycle Classics ?
     
  17. Bernhard

    Bernhard

    Joined:
    Apr 20, 2011
    And no water cooling to boot :!: :cry:
     
  18. Rohan

    Rohan

    Joined:
    Aug 26, 2010
    If we are talking that ex-winner of Daytona Manx :-

    1. Its not a rigid frame, its a plunger frame.
    2. Would have been built by Francis Beart, no factory involvement. ?
    3. Its FAR from original, as Mr Cohen admits.
    4. Including losing its kickstarter gearbox, a Daytona feature if ever there was one.
    5. And gained a visibly TLS front brake.
    6. And later racing seat.

    So as far as testing a Daytona bike goes, very little of it is original, so what are they testing ??

    Not much Typhoon content ere, iz there ?
     
  19. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    Have you read Francis Beart's book 'A Single Purpose' ?
    - Got the bike in the magazine mixed up with this :

    [​IMG]
     
  20. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    And yes, we are off topic. Haven't said I like your bike yet. Nice and original, just the way they should be. Years ago we had a G90 Matchless, it had the earlier style rod and piston in it. Had a swing arm frame which looked original, high level pipe and a map lamp on the tank. It performed particularly well. I think they are very rare these days. I've never seen another in the past 50 years.
     

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