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Thread: Help!

  1. #1
    CB750 New Member Mbrickman86's Avatar
    Join Date
    May 2019
    Lake stevens wa


    Hey guys Iím brand new here and Iíve got a 1980 Cb750k that has been in the shop for almost 3 months now, we rebuilt the carbs, changed plugs and wires, changed ignition coils, and replaced carb boots because they were cracked, the shop dyno tuned it and has it all dialed in but is saying the pulse generator is overheating after it runs for about 10 min which then is causing the bike to misfire. I havnt picked it up from the shop but am wondering if that sounds right

  2. #2
    CB750 Guru amc49's Avatar
    Join Date
    Sep 2015
    Fort Worth TX.
    Did anyone ever think to run a compression test or run the valves for clearances? The perennial problem with those engines. Then they lose valve seal and begin to misfire and the longer you drive it the worse it gets as valves burn. The valves are barely surface heat-treated and they recede very quickly with modern zero lead fuels, the valve then gets tighter and burns faster than spit. How most of them die but they run like crap for a long time before that.

    Set the valves at .005" (ignore the service manual figure of .003" and why they burn) and if valves aren't burned yet it will run better.

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