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  1. #1
    CB750 Member DSlo's Avatar
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    Engine bogs down in switching gears

    Fun issue after cleaning up the bike over the winter. Put in new plugs, a fuel filter after the petcock, cleaned the carbs and recently took the bike to get the carbs synced. Bikes idling around 20000 to 17000 rpm after warmed up for 10 minutes. Go out for a ride bogging a little in first then picks up, once I switch into second in really Boggs down before picking up the Rpms.

    I don't know if it an idle issue, fuel issue, or carbs not being synced right now. Any thoughts?

    Thanks in advance for your help as always!

  2. #2
    CB750 Addict dan1951's Avatar
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    Fuel filters flowing in right direction according to arrow marked on filter? I know You mean 2000 R.P.M. which is at least 900 to high, Did it run good last season? Unsynchonized carbs will run bad, Timing also.

  3. #3
    CB750 Member DSlo's Avatar
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    Hey Dan, thanks for the reply. Fuel filter is running parallel with the tank before the drain tube connecting joint. Once I get it warmed up I will dial down the resting idle to 1200 R.P.M to see if that helps. It ran great last season, resting idle was around 1700 which is pretty high. Hopefully the idle adjustment will do the trick if not I am guessing the sync is off or its not getting enough fuel due to the filter since nothing really outside of that has changed.

  4. #4
    CB750 Addict motogtp's Avatar
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    How do your spark plugs look? If it is running a little rich you might want to see if the idle circuits are open too far.

  5. #5
    CB750 Member DSlo's Avatar
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    Was able to pull the plugs over the weekend. The two plugs on the electric side were black while the two plugs on the oil side were clean and looking great. Put some new plugs in and seems to run better but still doing the bogging and the popping. How do you adjust the idle circuits? Sorry for the newbie question. I know the main idle screw, is that what your referencing?

    Thanks for the help!

  6. #6
    CB750 Addict motogtp's Avatar
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    What year and type (A, K, F)? Are the tops of the carbs round or keyhole shaped? Keyhole carbs have the pilot (idle) screws at the front (engine side) of the float bowl. Not sure on the round top carbs, I think on the sides.

  7. #7
    CB750 Member DSlo's Avatar
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    1975 CB750 K, round carbs. I believe the idle scree your talking about is on the side.

  8. #8
    CB750 Addict motogtp's Avatar
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    Maybe turn the screws in a 1/4 turn on the side with the black plugs and see if things get better. The main idle adjustment may have made a change. But I would get the carbs synced sometime soon.

  9. #9
    CB750 Member DSlo's Avatar
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    Appreciate the help, yah I took them to get them synced a while back and been having problems now starting the bike and running right which leads me to believe they are not synced correctly. Getting them re-synced this weekend. Hopefully the idol trick with help!

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