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Carb adjustment and break in on fresh rebuild

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    Carb adjustment and break in on fresh rebuild

    Five months after finding a broken cam chain, I have the motor reassembled and back on the bike. I replaced a bent exhaust valve, new valve stem seals, lapped valves, honed the cylinders, replaced cylinder rings, replaced cam chain, and replaced seals on the crank and trans shafts. I assembled with OEM gaskets everywhere. I've hooked up the wiring and reinstalled the exhaust. Just waiting on some Rotella from Amazon and shims from the Shim Club (thanks Ray!).

    I have the carbs in front of me and trying to figure out what to do with them. I assume I should reset everything: fuel screws 7/8 turns out and air screws 1.5 turns out is where I started before since I have K&N pods and stock exhaust. I guess I should also bench sync the slides before putting the carbs back on. Does this make sense?

    Once I get the valve clearances right, I plan to add oil, turn the motor by hand for a minute or two to circulate the oil, then start it up. Vacuum sync the carbs then do highest idle on the air screws then do a few laps around the block for a test ride. Last, I'm going to try the "hard" break in method of accel and decel while increasing the load for the first few accel decel cycles. I'm about 2 miles from a nice straight road without lights so by the time I get there, I should be ready to fully load the engine and go 25 miles out and back. A local Harley guy (owned a GS1000 years ago) says he does the 50 mile round trip until the motor stops making more power on the butt dyno. He says it's usually 2 or 3 trips (100-150 miles).

    Any comments on my order of operations? I'll be the happiest man on earth when I get this thing moving again!
    Jordan

    1977 Suzuki GS750 (My first bike)
    2000 Kawasaki ZRX1100
    1973 BMW R75/5

    #2
    Your plan sounds good to me. I'd recheck the valve clearances and torque the head again after the first couple hundred miles. Also, no need to go all nuts on the "hard break in" business. Just ride the bike firmly and use some throttle. Some people think that they have to thrash the bike from the first start or the rings won't seat but that's not correct.
    Ed

    To measure is to know.

    Mikuni O-ring Kits For Sale...https://www.thegsresources.com/_foru...ts#post1703182

    Top Newbie Mistakes thread...http://www.thegsresources.com/_forum...d.php?t=171846

    Carb rebuild tutorial...https://gsarchive.bwringer.com/mtsac...d_Tutorial.pdf

    KZ750E Rebuild Thread...http://www.thegsresources.com/_forum...0-Resurrection

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      #3
      If the bike was running fine before the cam chain break, I wouldn't change any of the carb settings.

      Fire it up and adjust from there if and as needed.
      1983 GS850G, Cosmos Blue.
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      Comment


        #4
        Thanks guys. I've been back and forth on whether to reset the carbs. The bike was running good before so it makes sense to start from there and fine tune.
        Jordan

        1977 Suzuki GS750 (My first bike)
        2000 Kawasaki ZRX1100
        1973 BMW R75/5

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