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Commando Top Speed? (2010)

Discussion in 'Norton Commando Motorcycles (Classic)' started by highdesert, Dec 21, 2010.

  1. daveh


    Jan 22, 2008
  2. Rohan


    Aug 26, 2010
    Thanks Dave, makes interesting reading.
    Big range of speeds there. !!

    The fastest point on the IoM track is towards the bottom of Bray Hill ?
    Thats where the gearing needs to be aimed at to avoid the over-rev ?
    Factory Manxs were geared for 145 mph there back into the 1950s ?
    Full fairings, of course....

    Yes its downhill....
  3. daveh


    Jan 22, 2008
    Creg ny baa to Brandish used to be the fastest section. It's about a mile (not certain of exact distance) quite steeply downhill and has a slight kink that is taken flat. I remember someone saying that Mick Grant had been clocked at around 195 mph on a Kawasaki 750 Triple in the late 70s here(?), but can't find the source, so it has to remain hearsay for the moment!

    The gearing would have to allow the bike to peak on the fastest downhill sections, so I guess gearing for 145 mph would be realistic even though they may not have been able to pull peak revs on the flat. It must have been tough climbing up from Ramsey Hairpin with a four speed 'box and tall gearing. I will try to dig out more hard data...!
  4. JimC


    Oct 12, 2007
  5. pommie john

    pommie john

    Nov 18, 2005

    It seems odd to me that in that article the bike was doing 131mph on the downhill run, and 117 on the uphill, then it suddenly is able to pull 145mph with just a change of gearing.
  6. DogT


    Jan 20, 2009
    This is a little late, but I did have my stock 69S on I95 in Maryland between Beltsville and Columbia, heading north one time on an early Sunday morning maybe about '73, close to red lined at 7000 on the tach in 4th gear. 19 tooth sprocket. The speedo was reading over 110, but I don't know how accurate it was/is. As I remember, it wouldn't go any faster.

    I never did it again, scared the bejesus out of me and I was only 30 years old.

  7. Rohan


    Aug 26, 2010

    You didn't read the article carefully enough ?

    Read it carefully - this is NOT a test of the factory bike of Dave Rawlins, and it doesn't do 145 mph, this is a test of a Gus Kuhn built bike. And obviously doesn't have the oomph that the Factory bike does.

    To get an 850 to go beyond redline (7000 rpm) on a 24 tooth sprocket would take some mumbo. No-one who posts here has done this, obviously. Its good that Nortons at least knew what they were doing...

    Be interesting to see an account of the run to give +140 mph, just the same.
    The Motorcycle Mechanics article in 1973 or 1974 had details, but they weren't there either.

    Wonder where Dave Rawlins is these days ?
  8. Rohan


    Aug 26, 2010
    Well someone thinks that Norman Whites ex-JPN bike goes pretty fast.
    And that he knows how to build them to go fast.


    Wonder what the winner thought - and if he/she gave it any stick ?
  9. Rohan


    Aug 26, 2010
    We are getting closer ?

    Down the bottom, with the pics of a supercharged Commando drag bike.
    Standard frame, just a little modified.

    "I remember attending the World Records meeting at Elvington in the 70's when a team from Norton Villiers ran a Commando production racer. Over the 1/4 mile it ran a very low 11, and with raised gearing 143 mph in the flying 1/4. Stunning stuff, especially as these were the averages of runs in opposite directions."

    Note the speed mentioned is now 143 mph.
    And the bike is now a production racer...

    So is the pic of Dave Rawlins on a Norton Racer in that scanned article what was run.
    Or the stock looking commando ?
  10. cash


    Nov 10, 2006
    I'm pretty sure the article is about the development of the HP850 tuning kits, and the bike was to run in the production class to take on the Japs. It mentions the bike was ran on public roads where it eventually broke the gearbox, the dreaded layshaft bearing. At the end of engine development the motor was tried in a road racer, that one in the photo? but proved unreliable on the circuits and had to detuned when it then did quite well.

    You'll see on page 87 Rawlins says about the sprint at Elvington;
    "We geared up the Norton for the flying quarter and it did 145mph. It was ridiculously fast, but it was still within the rules for tuned road bikes"

    Nowhere in the article can I find reference to fairings. Either way it's a remarkable feat for an old long-stroke parallel twin that all us Commando nuts should be proud of. :D

  11. Rohan


    Aug 26, 2010
    I would agree, and mixed up in the article is an interview with Dave Rawlins.

    But the HP bit is Gus Kuhns name for their hot-rodded version of an 850 ?.
    Note the Gus Kuhn "advert" in the article.
    When the sprocket was changed, it was done at Gus Kuhns.
    And when the gearbox broke, it was put on the train for London - Gus Kuhn was in London....

  12. snibor


    Jun 1, 2007

    Look I am no expert on Commandos (I do love them and have one ) but I have to agree with Pommie John on this in the math does not stack up .. He does know his Nortons and races one ...

    I do know a bit about gearing and the Island circuit ... and the inaccuracy of the old highlander speed trap ... don't forget it was 70s speed traps so not all that accurate ... and the press may have slightly exaggerated (don't forget who were their major advertisers of the time ) which they have a want to do at times ...

    I do however remember reading somewhere in the press that Peter Williams went through the Highlander on a 750 at a reported 140 something MPH .... which on 70s machines was the fastest part of the circuit (and yes John on a down hill incline ) ... on Modern bikes there are way faster sections over the mountain and sulby .

    assuming on the 750 commando , max revs of say 7500 (my guess ) , 140+MPH past the Highlander ..they would have huge issues carrying that gearing in top up the mountain unless he stayed in 3rd (which he may well have done by default as williams gearbox had all sorts of problems each time he rode the Island on the Commando and had he not would have won on quite a few more occasions ) ...

    I am currently building a Rob North BSA R3 for the manx next year and there is no way we can carry top gear from Ramsey up the mountain on the gearing we need for Sulby , down the other side of the mountain and such likes ..

    the gearing i will be using with the regs this year on the triple now being 850cc might make 150MPH (with the wind behind us ) and thats with 90RWHP , bike weight at about 340Lbs and we will still have to run up the mountain in 4th (on a 5 speed box ) to keep the power on @ around 9000 RPM ..

    so in summary yes with the right fairing , light weight rider and a long long straight , 150MPH may be possible but it would take awful high gearing to achieve and on a 750 (no matter what the spec ) i suspect would be very hard to achieve in the real world unless built specifically for the task like bonneville or somewhere like that .

  13. Holmeslice

    Holmeslice VIP MEMBER

    Sep 27, 2009
    This has been the best reading on this list for quite a while. There are some who've posted who know quite a bit about what they are talking about, and others who need to separate the facts from the fiction and marketing.

    I thank the last poster, who made a big clarification here - RWHP vs. BHP. I've seen BHP espoused in this thread quite a bit, and quite erroneously.

    That's all.

    Carry on.
  14. highdesert


    Jun 17, 2009
    In October I received an email from Jim Mosher stating that he just got back from Bonneville and that he had prepared a Commando of only 873cc that tied the 1000cc altered fuel pushrod class record of 155.722mph.

    Jim said that he pulled out all the stops but only raised the compression to 10.7 to 1.

    As far as I know, this is the absolute top speed ever attained by a Commando, certified.

    I can tell you that Mosher was pissed to only exactly tie the record. He said he will be back next year to claim that class record.

    Jim Mosher is recognized as one the very top vintage engine builders. He is currently building a double engined Indian for an assault on the top speed record for that class.

    I am very lucky that he lives only 70 miles from me. He completely rebuilt my own 850 this past May and June. It is one strong street motor.
    John Schmidt
  15. hobot


    Oct 19, 2005
    Interesting the earlier bikes seem faster per hp than more recent wonders.
    Air drag is the main drag so maybe bike size and posture and exhaust plume aim give or take a hand full of hp thrust. Wonder if tire profile become significant over the ton? Ms Peel on 1/2 mile straight that dropped 40 ft in undulations topped out 134 @ 6000 rpm then I put face down on clocks to make sure of what I was seeing to watch speed creep to 137 over some seconds but rpm stayed 6000-6100. Wind blast buffeted helmet to blur vision up close. Most pleasing though was ability to run right up to 130 w/o much delay before pull slacked off to need a few 100 yds more to top out. My sense was that she could of used more carb over a 34mm to go more.

    Any who very entertaining/educational to me as I'm in quandary on power-speed-gearing for daily legal-ish commutes - to spanking sport bikes up to some ungodly rate. Realistically I don't think I need over 150 on tracks to prove Peel handling. That's at skinny tire speed rating but likely could pull good past 160 just in case? After my own thrills, its elite moderns I'm after not vintage exotics I never come across. I've a Vesco full fairing+lowers, wonder if actually streamlines to matter?


  16. lcrken

    lcrken VIP MEMBER

    Mar 15, 2009
    That's a great result, and I'm sure Jim and Fred (the owner and rider) will bump it some more in 2011. But, just for clarity, let me point out a couple things. First, it's not a Commando. It's a stripped down Vendetta (Seeley replica by John Caffrey) frame running 17" wheels with a highly modified Commando engine. Frontal area is significantly less than a Commando. Second, it used a good dose of nitrous oxide to get the horsepower. Still, it's impressive that they ran that speed with no fairing. Here's a picture of Fred on the bike at speed.


  17. Rohan


    Aug 26, 2010
    Steve, It does seem that the early 750s were faster than later offerings - it is mentioned somewhere that Dennis Poore was quite keen to get some of the performance back for the 850s, but noise regs prevented this out of the showroom, hence Dave Rawlins and crew working on this, and the published Tuning Sheets to let owners do this.

    But to get that performance out of your bike, you'd have to be running a 25 tooth sprocket. ?
  18. Rohan


    Aug 26, 2010
    I'd agree, rear wheel horspower is all that counts. All the horspower numbers in this thread are engine horsepower though - how many published rear wheel horsepower tests for a Commando can we find ? The only ones I've seen anywhere were woefull - Norton Villiers claimed 60 horsepower, rear wheel dyno tests only showed 42 to 45 I seem to recall. Race bikes always seem to claim engine horspower, since the numbers are bigger - psyching out the opposition, as someone mentioned ?

    Anyone seen what Steve Maneys bikes can do, 80 horsepowers has been mentioned ?. And what about some of these 920cc and 1000+cc monsters...
  19. Rohan


    Aug 26, 2010
    This record, even if not from really a Commando, has to be easily beaten ?

    Someone has previously pointed out that Bonneville is at 6000 ft, so bikes are considerably slower there. And salt is not the lowest rolling resistance around, tarmac is faster ??
  20. Rohan


    Aug 26, 2010
    I'll just repeat, if you read that article carefully, although it is interviewing Dave Rawlins some years after his 145 mph run, the bike they are testing is NOT his. And DID NOT DO 145 mph.

    Although perhaps not made clear, it is supposedly a similar spec bike, with the same purpose in mind ? Gus Kuhn is mentioned repeatedly throughout, so the HP850 mentioned is a Gus Kuhn built effort. The clincher is they mention the cam - Nortons Tuning Sheets mention the 4S cam, Gus Kuhns bike was built using a SS cam (not even the 2S).

    So they DID NOT just change the gearing and do 145 mph.
    Not on the Gus Kuhn bike anyway.....

    Dave Rawlins might have.
    But it was from 1/4 mile spec to high speed testing spec, not mid speed testing.

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