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Valve adjust and far less power

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  • Valve adjust and far less power

    I'm guessing my bike might have between 10K and 35K miles on it but there's little way to know the engine's actual mileage. Unfortunately I did two major things at one time--completely disassembled and cleaned the carbs (maintaining exact pilot screw turns and syncronization settings) and adjusted the valve lash. It pretty much had 0 valve clearance and would take a while to start, sometimes backfiring once before getting going, but it pulled strong and there was an immediacy of twisting the throttle and getting power. For a Hawk it felt fast-ish.
    After putting in the feeler gauge and adjusting it to have slight drag for first the front, then the rear cylinders at the factory spec, it starts immediately and revs perfectly with no load. However out on the road it has WAY less power. Going uphill at 65mph isn't quite WOT, but I need a lot more throttle than before. There is no immediacy between twisting the throttle while riding--there's no way on the planet it could pop a wheelie now, and before it was kind of possible. Is my gap too large? It's not impossible, but I don't think it's the carbs. Any suggestions?
    Hawk with many differently shaped fuel tanks.

  • #2
    Originally Posted by Henway
    I'm guessing my bike might have between 10K and 35K miles on it but there's little way to know the engine's actual mileage. Unfortunately I did two major things at one time--completely disassembled and cleaned the carbs (maintaining exact pilot screw turns and syncronization settings) and adjusted the valve lash. It pretty much had 0 valve clearance and would take a while to start, sometimes backfiring once before getting going, but it pulled strong and there was an immediacy of twisting the throttle and getting power. For a Hawk it felt fast-ish.
    After putting in the feeler gauge and adjusting it to have slight drag for first the front, then the rear cylinders at the factory spec, it starts immediately and revs perfectly with no load. However out on the road it has WAY less power. Going uphill at 65mph isn't quite WOT, but I need a lot more throttle than before. There is no immediacy between twisting the throttle while riding--there's no way on the planet it could pop a wheelie now, and before it was kind of possible. Is my gap too large? It's not impossible, but I don't think it's the carbs. Any suggestions?
    Have you checked and made sure you are running on both cylinders?

    How are the slides moving?
    Don't spend money and buy, spend time and learn.

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    • #3
      I think you need to review how you are setting valve clearance. It would not have run right with 0 clearance.
      Brian - Richland, WA
      1991 Hawk GT

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      • #4
        Yeah, with zero clearance on the valve lash, it should not have run correctly at all. After adjusting the valves, which they rarely need, I always go back and check the carb synch. Yes, you can get them close adjusting on the bench, but I like to verify after doing the valve adjustment. Aside from that, look at the plugs and see what they tell you (plug chop time).
        ASMA #139

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        • #5
          I've seen them go tight before and have about no clearance, not all of them, but a valve or tow is not abnormal.

          I would think if he set them while on a lobe he would here that...
          Don't spend money and buy, spend time and learn.

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          • #6
            I'll break out the mercury vacuum and sync it first to see if that's the issue, but I think I'll have to get in there and adjust the valves again. I think 3 of the 6 had extremely little to no lash. The carb slides operate perfectly and the diaphragms are in great shape and they return to the bottom at the same speed. I get replacements for them in the mail this week and I have new cover gaskets anyway.
            Hawk with many differently shaped fuel tanks.

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