Questions/Benchmarking-->EXPECTED HORSEPOWER- 82 GS750EZ.

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  • Anonymous
    #1

    Questions/Benchmarking-->EXPECTED HORSEPOWER- 82 GS750EZ.

    Ran a thread awhile back..on Modified bike. Want feedback....

    GS750EZ 1982 TSCC engine, 16 valve

    Horsepower - on a dyno

    (rear wheel = 77 at 8500 RPM. Redline is 9500)

    (rear wheel = 60 at 6000 RPM.)

    Maybe at the crank peak was 89 HP.

    IS THIS REASONABLE GIVEN THIS ENGINE AND THE MODS BELOW? WHAT DID A STOCK BIKE GET AT THE REAR WHEEL? WHAT ABOUT THE CURVE? 60 AT 6K RPM is pretty good, I'd think. 77 is reasonable too given the curve bias and mods? Curious. What would others use for lobe centers?

    Modifications:
    I blend ported the heads, opened up the airbox intake opening (from 3" stock to 3.6" square), put in a GS1100 intake cam, put a pipe on it, changed needles and went from 112 mains to 130 mains. Sniffer said main was set 3-4% CO) CAMS were degreed I think 102 and 108 at 0.040" lift.
    Tags: None
    • AOD
      #2
      Sounds peppy. 8)

      What were the original ratings for the bike from the factory?

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        • lhanscom
          #3
          If you want more hp I would crank your intake cam up to 108, maybe even 110 on both, check clearances, and dyno it again. You will lose some on the bottom end though.

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            • Anonymous
              #4
              Cams / Stock Rating and HMP........

              Gotcha on the cam settings. Thanks. I don't have the bike anymore. I sold it because it was getting a little squirrely when I accelerated hard. It had a fork brace AND a frame brace I added between the front cradle downtubes (like the 1100's come with stock) but alas, the frame in the rear has that weakness on the sprocket side, soooooooo...I sold it. Didn't know about the GS site at the time. What a ball I would have had tinkering more.

              To answer the other post, stock the bike had 61 horsepower at the crank (I think it was crank and not rear wheel). If I estimate a 15% HP loss through the drivetrain, that means I went from 61 to 89 HP and from the sounds of it, it was tuned high-midrange power (peak at 8500 RPM). The main jet increase from 112 to 130 says it all....and the midrange flow was phenomenal..if you know that main jet increases also boost the needle mixture in acceleration mode, and I still had to go to an aggressive taper needle, that's why I was getting 60 at the REAR wheel at 6000 RPM.

              Any racers out there know a place that used to be in Framingham Massachusetts called Harry's Machined Parts? (HMP) A guy there did the valve seat cuts and shimmed the valve springs 0.020" inch to avoid float. The motor would pull through past the 9500 redline to 11,800. Yippeeee. This guy won the NHRA in 1988 so he had all the street racers from New York City getting their motors machined by him. His name was something like Richard Stetson and he had a great golden labrador retriever doggie who hung around the shop. Anyhow......anyone remember him? Memories for anyone? Heh heh. - Dieter

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