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Top Speed of a fully worked SR500?

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  • Top Speed of a fully worked SR500?

    Overheard a guy say he got "250km/h and it was still pulling" out of a SR500 he had worked on.

    He is the worlds greatest motorcycle mechanic acccording to himself and his apostles so maybe he's right.

    150km/h is top speed of a stock SR so I find it a stretch to think it could get to 250km/h regardless of what was done to the engine.

    What do the gentlemen of PSB think, who was doing the pulling, the bike or him?

    Himalayan Heroes W E B S I T E , F A C E B O O K

    Perth Cafe Racers F A C E B O O K

  • #2
    Him...

    Although a 499cc NSU streamliner hit 338kph in 1956...

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    • #3
      I remember reading an article on SR's in 'Performance Streetbike' years ago where one of the 2 guys featured spent a lot of time trying to get his to do 200kmh.
      If my memory is correct he got close but never quite made it..............

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      • #4
        Depends how high the herc he rode it out of was flying at the time. You'd need some streamlining you'd also need some silly gearing and possibly forced induction of some description. On the flip side was reading an article on historic car racing and they were talking about the continuous development that is currently going on where motors reliably running today are putting out more HP than they did way back when in full house factory racing trim.

        The other question is how was this 250 measured off the stock speedo that was never ever calibrated to read anywhere near that high? I'm defiantly on the side of him letting his enthusiasm get in the way of the facts.
        Harvey community radio has a motorcycling show listen over the web here www.harveycommunityradio.com.au ,Facebook here http://www.facebook.com/pages/The-Mo...34691323302991 yes I am the goose that hosts it.

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        • #5
          yeah i doubt it too....

          Nero - if it were true, an XS750/XS1100 speedo could show those speeds, the front wheel speedo drives are identical to the SR500's

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          • #6
            Doubtful but absolutely mega cool if true.
            "Starin' at the world through my rearview"

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            • #7
              how many horespower?


              get him to keep digging by providing even sillier facts.

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              • #8
                After owning one 160 indicated was scary enough and up near the limit of mine. (Exhaust, miki carby, Pod, oil cooler etc)
                The problem is getting enough HP out of the engine to do that speed would require... well basically a different engine hah.
                After a certain amount of work and a big enough piston the head needs extra bolts to stop it simply blowing off the bottom end lol.
                Motorbikes run on fire and air. Its elemental -Matt Kelly

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                • #9
                  Does this person have any other credentials to point towards this being true? With standard gearing this is 66% more revs out of a big single. There'd be some serious shaking going on there without some extensive balancing work. Or you could gear it higher and have a long run up I suppose. Either way, what's the point? Spending massive amounts on a bike like this when relatively cheap off the shelf standard bikes have this sort of performance? Or killing the acceleration to make the bike impracticable, to get a top speed to brag about? And 250km/hr on an unfaired bike, that's not easy to hang onto either.

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                  • #10
                    Horseshit.

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                    • #11
                      I got 100km/h out of a 50cc moped before it threw the belt, locked the back wheel and almost threw the rider, 500cc is ten times as big and allowing for a four stroke non sports bike making half the power per capacity of a ported 2 stroke with huge carb and expansion chamber, I'd say he must have been stuck in second, that combo should do at least 500km/h
                      Do you remember the good old days before the internet?

                      when arguments were only entered into by the physically or intellectually able.

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                      • #12
                        Can't find the stock horsepower of one, 40-45hp seems to be quoted a lot, but let's be generous and call it 50hp

                        Top speed seems to be about 160km/h

                        We know from aerodynamics that the square rule applies, to do double the speed requires 4 times the power, to do 3 times the speed needs 9 times the power, etc.

                        Let's work out the power required to do 250km/h

                        250/160 = 1.5625 (the top speed is increasing by a factor of 1.5625)

                        Apply the square rule -> 1.5625 * 1.5625 = 2.4414 (to do this new top speed you need 2.4414 times the original horsepower)

                        New horsepower required = the original 50hp * 2.4414 = 122.07hp
                        (or if it only had 40hp, we only need 97.656hp)

                        Will a single cylinder 500cc bike ever produce 100-120 horsepower? No fucking way

                        MYTH BUSTED
                        For LAMS information and resources - http://www.perthstreetbikes.com/foru...thread-156358/
                        For LAMS discussion and to ask questions - http://www.perthstreetbikes.com/foru...thread-143289/

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                        • #13
                          How fast will a Postie bike go in 3 rd??

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                          • #14
                            Originally posted by Barfridge View Post
                            Can't find the stock horsepower of one, 40-45hp seems to be quoted a lot, but let's be generous and call it 50hp

                            Top speed seems to be about 160km/h

                            We know from aerodynamics that the square rule applies, to do double the speed requires 4 times the power, to do 3 times the speed needs 9 times the power, etc.

                            Let's work out the power required to do 250km/h

                            250/160 = 1.5625 (the top speed is increasing by a factor of 1.5625)

                            Apply the square rule -> 1.5625 * 1.5625 = 2.4414 (to do this new top speed you need 2.4414 times the original horsepower)

                            New horsepower required = the original 50hp * 2.4414 = 122.07hp
                            (or if it only had 40hp, we only need 97.656hp)

                            Will a single cylinder 500cc bike ever produce 100-120 horsepower? No fucking way

                            MYTH BUSTED
                            B+

                            Solid effort but no practical and no explosions.
                            Filbert on Moto Guzzis;
                            Originally posted by filbert
                            it's like a ducati with the motor put in sideways for people who are too scared of the power of harley davidsons

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                            • #15
                              But what if you did this to it Sr 500 Supercharged - YouTube
                              "Starin' at the world through my rearview"

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