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Commando engine into Dommi ?

Discussion in 'Norton Commando Motorcycles (Classic)' started by Chris, Jan 10, 2019.

  1. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    The little uns can still be fun tho. My Dresda Daytona’s power band was between 8-10k. It really was akin to riding a two stroke and was a SERIOUSLY fun bike!

    You’re dead right about being spoiled Glen, in fact I’d say it’s more like having our calibration screwed up... when I was regularly riding a 1330cc Egli Vin I jumped on a mates very nicely sorted 850 Commando and, like just like you said about the Bonnie, thought “is that really it”!?
     
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  2. Jagbruno

    Jagbruno

    Joined:
    Jan 6, 2014
    My everyday bike is a Slimline Featherbed with a tilted hot (PW3, etc.) 850 Mk2a engine. The crank is balanced (around 72%) for rigid mounting in the frame. The handling is excellent, thanks to Manx dampers and French Fournales oleo-pneumatic shocks. All in all, it is a very pleasing bike, equally at ease on the track with its full Dunstall fairing or on the road, significantly lighter than a stock Commando and way more potent than a Dommie.

    [​IMG]
     
    Last edited: Jan 12, 2019
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  3. acotrel

    acotrel

    Joined:
    Jun 30, 2012

    I think Geoff Monty had a 500cc Daytona engine in Ducati 250 frame. It would get lost in a featherbed. I believe the 500cc Daytona engine did not have a proper timing side bearing until 1973. And where would you get a close 5 speed box for one at a reasonable price ? In historic racing, there is no real regard for history. The Senior used to be the most common class for large bikes - 500cc max. In Australia we also ran an Unlimited class but it was relatively unimportant.. There days everybody believes big is better, but the truth is that most cannot compete effectively with a small four-stroke - cannot ride them properly - and it is NOT easy. A good guy on a hot 250cc Ducati can give a lot of guys on much bigger bikes a scare. The thing which stuffed my own 500cc Triton was the lack of a 5-plus close ratio gearbox. You either lost the race at the start of the straights or at the ends, depending on the overall gearing.
    In building any race bike - if you have not got the gearbox, you have not got the bike.
    650SS Nortons don't usually have 6 speed close ratio gearboxes. With a bigger bike, it is not so important, but still makes a difference.
     
  4. ashman

    ashman

    Joined:
    Jul 11, 2010
    I built my hot 850 in the Wideline Featherbed back in 1980 I made my own engine mounts for the tilt motor, crank balanced for the Featherbed frame and other little goodies, this bike is super light, handles great and a pleasure to ride.

    Ashley
     
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  5. baz

    baz VIP MEMBER

    Joined:
    May 26, 2010
    There is an awful lot of tube in this frame ,and I agree with the others it looks like a tight fit
    But well worth it in my opinion
     
    Last edited: Jan 11, 2019
  6. Chris

    Chris VIP MEMBER

    Joined:
    Jan 21, 2008
    Hi
    Baz you are right, worth it.
    Ashley Jagbruno I do think you have the best of both worlds. I think the bigger engine is just " right"
    Acotrel o dear! Percy had the timing side bearing in 67, road bikes in 69. The works 500 came second to Ago at the Belgium gp timed at blistering top speed he averaged 116mph. If you read Percy's book he says it was a difficult bike to ride (a bugger)
    Nova make 6 speed race boxes £2,350. I put up with a Quaife MK2 5 speed. As to Geoff Monty, after the Monard pre unit engines. He was running unit 650 cases with Weslake 8 valve head & short stroke barrels. Ask me how I know.
    Plus you completely missed the point! Your Triumph 500 pre unit days you state it all the time. Dangerous!, difficult to ride, accident waiting to happen. Which is why I am looking to change to a bigger engine. It's more fun to ride.
    A 350 Ducati is a far nicer bike to race than a 500 Dommi. Got to say my Daytona is a much better bike to ride than my Dommi.
    Rant over.
    Project is a definite go.
    Chris
     
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  7. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    Of all the race bikes, an Aermacchi Ala D'Oro 350 might have been the best ever. Either that or a Seeley G50. Racing is about having fun and big is not necessarily better. Finding a good race class in which to compete, is always a problem. With the Percy Tait Triumph, doing that stuff with a 500cc twin can be very dangerous when you increase top end power at the expense of bottom end. My 500 was fast enough to win races, but the anxiety was horrible. You only had to blink in a corner and it would step out and crash you. With a bigger motor, you can blow the other guys off down the straights, but that is not what racing is really about. If your bike is underpowered, you have to work harder and get smarter. There are two parts to every race circuit - the corners and the straights. If you get passed at the end of a straight, you can often ride under the other guy at the next corner.
     
    Last edited: Jan 11, 2019
  8. ashman

    ashman

    Joined:
    Jul 11, 2010
    A Featherbed frame and a hot 850 Commando motor that has been balanced right, my crank balanced at 72 % and you get a very smooth bike to ride with no vibrations at all, I could never understand why Norton never balanced the Commando engines better in the first place.
    Balancing the crank is the cheapest way of building these bikes you can spend lots and lots of money going down Jim's way with lighten pistons and Carlo rods etc etc which I would love to do one day but when I built my Featherbed/Commando I wasn't working at the time and built it on the cheap and over the last 38 years been improving it when I had the money and time, but what I done first up worked out great.
    I lot of people recond my bike be unrideable going hard mounts but when I first built it but I proved otherwise and have a very smooth bike that handles so much better than a Commando, so much lighter and with the work done to the motor it surprises a lot of modren bikes with the torque it has.
    So I say go for it.

    Ashley
     
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  9. Jagbruno

    Jagbruno

    Joined:
    Jan 6, 2014
    Come on now, Acotrel.
    You have been telling us for years about your unridable 500...ok, so your bike was bad, but don't make it a generality.
    My Daytona sure is nowhere as potent as Percy Tait's was, but it is a nimble, light, very pleasant track bike. I know at least 3 other successful racing Daytona's that are anything but pigs.
    I respectfully suggest you move on.
     
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  10. Jagbruno

    Jagbruno

    Joined:
    Jan 6, 2014
    I can say the exact same things as Ashley about my Featherbed Commando 850 , which as you know is technically very similar to his.
     
  11. ashman

    ashman

    Joined:
    Jul 11, 2010
    Another thing with the Featherbed frame Commando is the Featherbed is shorter than a Commando bike and the best part its like riding on rails, the harder you push it in the corners the better it handles and having a hot motor makes it more fun.

    Ashley
     
  12. jseng1

    jseng1

    Joined:
    Nov 26, 2009
    A Commando engine in a Featherbed is a nobrainer in my opinion - especially if its a low vibration version. My favorite thing is blasting off to a jazz gig on the 1959 wideline (sax goes in a backpack of course).

    [​IMG]
    50,000 miles on the motor so far
     
    Last edited: Jan 12, 2019
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  13. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    Nice for a road bike, but in racing we have idiots making the rules. My ideal race classes would be simply for bikes with four-stroke air-cooled single or twin cylinder motors of less than 500cc for the singles and 1000cc for the twins.. - No other rules.
     
  14. 84ok

    84ok

    Joined:
    Aug 10, 2014
    any particular reason for going vertical with the engine?

     
  15. ashman

    ashman

    Joined:
    Jul 11, 2010
    Its a Dommie motor they sit vertical in the Featherbed frame, a few people who put Commando motors in Featherbed frames set them up vertical but they don't look right in my opinion, I set mine up like it should with a Commando motor in it.

    Ashley
     
  16. oldbeezer

    oldbeezer VIP MEMBER

    Joined:
    Nov 2, 2017
    Jeez another squid riding a bike in shorts and flip flops. :rolleyes:
    Seriously tho nice bike.
     
  17. ashman

    ashman

    Joined:
    Jul 11, 2010
    I am sure Jim would wear the right gear when out and about, who would get all in there riding gear to take a shot of his bike.

    Ashley
     
  18. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    If you covered the bottom tubes of that Dresda frame with rags and sat the motor and gearbox in it on chocks, you would soon know if it was going to make sense. Cutting out and drilling engine plates is the easy part. Getting the motor and gearbox positions right is important. You will probably find you cannot get the head off while the motor is in the frame. I usually start with cardboard and scissors and oil the crankcases to get an imprint to locate the holes in the plates. If you buy ready-made engine plates, they are more likely to be wrong than right. Slotting holes is bad.
     
  19. acotrel

    acotrel

    Joined:
    Jun 30, 2012
    I had a friend who lost his big toe doing that. He fell off and it went under the footrest.
     
  20. acotrel

    acotrel

    Joined:
    Jun 30, 2012

    Chris, the main problem with any race bike is finding a race class which suits it. My 500cc Triton was excellent for what it was, but it was always raced against bikes which were double the engine capacity. I liked it 'some things are so bad that they are good', but I don't need that sort of anxiety. In 12 years of racing, I only ever got one chance to ride it in the correct capacity class. And then it was against the top guys in Australia. (The Harvie Wiltshire Trophy race).
     

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