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5050 rpm seems a lot for 70mph....

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    5050 rpm seems a lot for 70mph....

    I think I have one tooth larger in front and 5050 seems really high for digitally calibrated 70mph. It really seems to dislike going 80. Do people run at 5000rpm all day long with no problem? Is that no problem on Hawks? Just curious. Drop another 2 teeth on the rear and shorten the chain 2 links?
    Hawk with many differently shaped fuel tanks.

    #2
    Check to see what size sprockets you are using. I have no issues running 5k rpm all day long (16f, 46r).
    Last edited by Talon; 05-19-2022, 06:11 PM.
    ASMA #139

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      #3
      throw a 17 on. its cheaper and quicker
      Gino
      Chain Roller

      NEVER UNDERESTIMATE THE PREDICTABILITY OF STUPIDITY

      2012 CCS LRRS ULSB Champion
      2012 CCS LRRS P89 Champion
      2008 CCS ULSB National Champion
      LRRS HAWK GT Racer CCS Expert #929
      ECK RACING

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        #4
        I never ride below 4k out on the two lane roads. When I'm on twisty long stretches it's 3rd or 4th gear and above 5k all the time in 4th or 6500 in 3rd. 5050 rpms is about 59% of redline of 8500. Not a big deal. With stock tires, gearing and gages 80 is the new 70 (speedometer error). Here are a couple of charts. One I made.

        SPEEDOMETER.jpg gearco-road3 ct2.jpg
        Last edited by BillnOroville; 05-20-2022, 10:06 AM.
        Bill,
        88 Blue Hawk (bike #39), 89 Red Hawk, 2021 Rebel 1100 (bike 41) Some Past/sold in reverse order:,FZ09,97 Magna #1&2 , 97 VFR750F, 87 VFR400R, 88 Hawk, 86 SRX 600, 77 RD400, 79 CB650, 04 VFR, 88 Blue Hawk, 89 Red Hawk, Yamaha SRX600, Harley 1200C, Yamaha RD400, Harley 883R, Yamaha 750 triple, Vlx600, Honda 450, Honda 400, CB550F, Kawasaki H1, BMW R69US, Yamaha R5C 350, Honda 160, Bridgestone 175, 1950 Harley 74 w/sidecar, 65 Harley 250 Sprint, 1948 Harley and my 1st bike-1941 Harley 74 knucklehead my dad gave in1963.

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          #5
          Glad I checked--I have 15/43 gearing now at 520. I found the original 16 and it doesn't fit because it's 525.
          Quick math shows 15 front = 70mph, 16 = 75mph, 17 = 80mph. The website from above shows I'll tach 4475 with a 17 for 70mph. (it has a 3mph difference to my data because rear tire size is irrelevant when I'm measuring it at the front and they don't account for that--using 160/60 got me to 3mph difference)
          https://www.amazon.com/Pro-tek-Honda...08KHPZH4B?th=1

          I've been looking at cushioned ones from JT.
          On the website the NT650 is only showing in 525.
          I've looked at their specs and there isn't a single 520 with Z-13 inner teeth and the same offset, especially bigger than 15 teeth

          I'll order the 17 Protek because someone last year said it worked well with their 17/42.
          Hawk with many differently shaped fuel tanks.

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            #6


            IMG_1437.jpeg

            So this is the result of my Hawk’s dyno testing. Not a fire breather, but once you have it in mind the power output range, it may change approach to riding. You’ll note the max torque at ~7,000 RPM and max horsepower output at ~8,000 RPM. I know this thread is more about gearing than output #’s, but I generally ride my Hawk on the backroads at 5K to 7K. Pulls and decelerates really well in this range and she’ll run that way all day. Not certain why we see the 6th gear question often asked, as I think (for what it is and my riding style) the stock gearing works very well.

            This forum is entirely dedicated to wasting time and money modifying a slow motorcycle. - joel

            Nothing like a project to keep you busy, slowly draining funds out of the wallet! - spacetiger

            Our Hawks have all the power any mature, sensible rider can use on any street or highway without carrying around excessively unnecessary big-bore weight and power - squirrelman

            Bike builds can be and most time are art and expression. To take something mass produced and impersonal and make something personal that you can't stop staring at as you walk away. There is nothing I find more satisfying than looking at something cool and beautiful and thinking "I made that". - 6

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              #7
              Mine falls off harder and earlier than yours. Initial with Two Brothers exhaust wasn't happy. Back to bone stock but 132/126 jets gave the best dyno numbers.
              Hawk Two Brothers pipe vs. stock.png RC31E-2003431_014.png
              Hawk with many differently shaped fuel tanks.

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                #8
                I have stock carbs, gearing and tyres and on a ride last night I was doing 4,300rpm at 70mph it pulls well from 70 to 85mph but that's as fast as I can go without being blown off the back.


                No idea if the Speedo or rev counter are accurate.
                Last edited by Fastmongrel; 05-22-2022, 04:29 AM.

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                  #9
                  Originally Posted by Fastmongrel View Post
                  I have stock carbs, gearing and tyres and on a ride last night I was doing 4,300rpm at 70mph it pulls well from 70 to 85mph but that's as fast as I can go without being blown off the back.


                  No idea if the Speedo or rev counter are accurate.
                  First, crouch.

                  Second, no. The speedos are almost never accurate.

                  But third, sounds like a good crushing rpm.
                  Don't spend money and buy, spend time and learn.

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                    #10
                    Just for perspective a triumph street triple r 675 is running 6,000 rpm at 70.

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                      #11
                      Going from a 15/42 to 17/42 transformed the bike. 4400 rpm at 70mph is wonderful and changed the character of the bike. Cheapest and most significant upgrade I've ever done.

                      The Hawks don't max out at 11,800rpm like the street triple. 6000 rpm of 11,800 is 51% for the triple. 4400 of 8000 for the Hawk is 55%, so I'm still taching higher than your rpm/max rpm with my much taller gearing.
                      Hawk with many differently shaped fuel tanks.

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