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    Originally posted by Dink
    I have had the Tractor out to 10 500 rpm in top gear 8O luckily this is only 1000 rpm past redline
    This is what I find interesting. :?
    These bikes make their peak HP before redline. IN TOP GEAR, STOCK GEARING, LEVEL GROUND, STOCK OR MINOR MOD'S, how can the engine pull more rpm's past redline when the HP is dropping off?
    I can believe reaching/passing redline in a lower gear, but top gear?
    Not trying to cause trouble here Dink, or anyone else. This just has me scratching my head.
    And on the seventh day,after resting from all that he had done,God went for a ride on his GS!
    Upon seeing that it was good, he went out again on his ZX14! But just a little bit faster!

    Comment


      That would be because although the engine has passed its peak hp rating, the hp output while declining, is still greater than the sum of the resistances of parasitic, induced and mechanical drags. Where the drag and hp curves intersect beyond the peak hp level is where the top speed will be. Depending on gearing, top speed may be almost anywhere on the hp curve.

      Earl

      Originally posted by KEITH KRAUSE
      how can the engine pull more rpm's past redline when the HP is dropping off?
      I can believe reaching/passing redline in a lower gear, but top gear?
      Not trying to cause trouble here Dink, or anyone else. This just has me scratching my head.
      Komorebi-The light filtering through the trees.

      I would rather sit on a pumpkin and have it all to myself than be crowded on a velvet cushion. H.D.T.

      Comment


        Originally posted by X gs X
        i can go roughly 220mph on my 1982 GS 650
        I actually find that statement very interesting, as I have an '83 GS650GLD, and my speedo tops out at 160mph. I have had it up to 108mph with the RPM's at ~6800 and a redline of 9500.

        I'd like to know how you can get to 220mph. Serious engine mods?

        Comment


          Originally posted by KEITH KRAUSE
          Originally posted by Dink
          I have had the Tractor out to 10 500 rpm in top gear 8O luckily this is only 1000 rpm past redline
          This is what I find interesting. :?
          These bikes make their peak HP before redline. IN TOP GEAR, STOCK GEARING, LEVEL GROUND, STOCK OR MINOR MOD'S, how can the engine pull more rpm's past redline when the HP is dropping off?
          I can believe reaching/passing redline in a lower gear, but top gear?
          Not trying to cause trouble here Dink, or anyone else. This just has me scratching my head.
          No problem Keith, allow me to qualify it by adding I had 30 miles of road to play with, uphill downhill and all
          Dink

          Comment


            Mine was on the Hay plain...long flat and boring, but it did not take much to get up to speed. I was thinking about police, but I suppose 200...220...not much different on a ticket really

            Comment


              Lets try a different perspective. If I remember correctly from my rambling around the net and reading specs on various GS models, a 650 is about 60 hp and I think top end spec'd by Suzuki was 115 mph. Its an aerodynamic fact that drag increases as the square of the speed. Or, said differently, if you double the speed, then drag will increase fourfold. Since top speed is reached when hp is in balance with drag, then drag controls speed. Without drag, we could go 1000 mph with 1 hp. So, to accelerate your 650 to 230 mph, the hp required will be 4 x 60 or 240 hp. This only accounts for induced drag or drag from air flow. I havent included parasitic drag ( drag from form factor), or mechanical drag values such as internal engine parts, tire contact patch, etc. The reality is that for an open bike, it probably will require something in the range of 280 to 300 hp to reach a speed of 230-240 mph.

              As a rule of thumb, for low drag, aerodynamically efficient bikes such as the Hayabusa, you can figure that as speeds of 200 mph are approached, it will require aproximately 1 hp per mile per hour. You want to break 200 mph on your busa, then youre going to need about 200 hp.

              Earl


              Originally posted by WhyteGryphon
              Originally posted by X gs X
              i can go roughly 220mph on my 1982 GS 650
              I actually find that statement very interesting, as I have an '83 GS650GLD, and my speedo tops out at 160mph. I have had it up to 108mph with the RPM's at ~6800 and a redline of 9500.

              I'd like to know how you can get to 220mph. Serious engine mods?
              Komorebi-The light filtering through the trees.

              I would rather sit on a pumpkin and have it all to myself than be crowded on a velvet cushion. H.D.T.

              Comment


                I've had every bike I owned topped out...the '78 gs1000 I had had no speedo...my 850 only goes to 85...past that easily in third gear...a '71 cb750 I had went 135 on the speedo...oh, I take that back...I never had my xs1100 wide open...it just didn't feel secure over 130. I go much nearer the speed limit most of the time, but, there are occasions...

                Comment


                  145mph at 9500 rpm too scared to push her further


                  Kevin

                  Comment


                    [quote="earlfor"]Lets try a different perspective. If I remember correctly from my rambling around the net and reading specs on various GS models, a 650 is about 60 hp and I think top end spec'd by Suzuki was 115 mph. Its an aerodynamic fact that drag increases as the square of the speed. Or, said differently, if you double the speed, then drag will increase fourfold. Since top speed is reached when hp is in balance with drag, then drag controls speed. Without drag, we could go 1000 mph with 1 hp. So, to accelerate your 650 to 230 mph, the hp required will be 4 x 60 or 240 hp. This only accounts for induced drag or drag from air flow. I havent included parasitic drag ( drag from form factor), or mechanical drag values such as internal engine parts, tire contact patch, etc. The reality is that for an open bike, it probably will require something in the range of 280 to 300 hp to reach a speed of 230-240 mph.

                    As a rule of thumb, for low aerydynamically efficient bikes such as the Hayabusa, you can figure that as speeds of 200 mph are approached, it will require aproximately 1 hp per mile per hour. You want to break 200 mph on your busa, then youre going to need about 200 hp.

                    Earl






                    Well put Earl.

                    Comment


                      Originally posted by lartross
                      a '71 cb750 I had went 135 on the speedo.
                      With what mod's?
                      And on the seventh day,after resting from all that he had done,God went for a ride on his GS!
                      Upon seeing that it was good, he went out again on his ZX14! But just a little bit faster!

                      Comment


                        nary a one [mod] I just twisted the throttle and left it there at 1 am on the freeway. I see what the engineer says, I'm telling you what I saw on my speedometer. Take it or leave it.

                        Comment


                          Originally posted by lartross
                          nary a one [mod] I just twisted the throttle and left it there at 1 am on the freeway. I see what the engineer says, I'm telling you what I saw on my speedometer. Take it or leave it.
                          Something was wrong with the speedo then. No stock CB750 can go anywhere near 135. In fact, the '69 and '70 models were infamous for going faster in 4th than in 5th. About 110 on level ground. A decade later in '81, they still wouldn't go past 110. My best friend had a '81, freshly broken in. We both tried top speed runs on it. He hit 108 according to my GS1000's speedo. Then I tried it and hit 110.
                          There's been a lot of speedo errors in this thread I think.
                          And on the seventh day,after resting from all that he had done,God went for a ride on his GS!
                          Upon seeing that it was good, he went out again on his ZX14! But just a little bit faster!

                          Comment


                            1982 GS750EZ

                            Rejetted carburator and pipe - 1982 GS750EZ would redline in top gear....figure 128 + . The dyno'd rear wheel horsies were about 65 at the time.

                            Later - modified it to 77 rear wheel horsies - so not sure what it would have done then. - Dieter

                            Comment


                              After about 8 Budwisers and a couple of hits of meth, I have gotten my pocket bike up to 1300mph. Or maybe it was 13, one or the other.
                              Currently bikeless
                              '81 GS 1100EX - "Peace, by superior fire power."
                              '06 FZ1000 - "What we are dealing with here, is a COMPLETE lack of respect for the law."

                              I ride, therefore I am.... constantly buying new tires.

                              "Tell me what kind of an accident you are going to have, and I will tell you which helmet to wear." - Harry Hurt

                              Comment


                                198Km/h or 123mp/h whichever way you like to look at it....

                                Slightly up-hill, long straight, on my 1977 GS750. I had to back off for an almost right angle bend (taken at 85Km/h), but on the straight there was still heaps more left in it.

                                a few mods:
                                15/36 (530) sprokets
                                K&N pod filters
                                bigger (125) jets
                                Unknown single alloy muffler on 4-1 system
                                Retshal bikini fairing

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