Engine swap, 81 750 for a 78 750?

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  • AmazaTX
    • Feb 2026
    #1

    Engine swap, 81 750 for a 78 750?

    Hey guys, hope y'all are well, first post here.

    Alright got an 81 gs750(L?) and after a couple months after purchase spun a couple rod bearings. I have since read about their reputation on that. I love the bike and already have the replacement bearing and rods to make her well again but if it truly has a bad oiling system, then my question is how much longer til the next episode. So I have read about the 1100 motors being a bolt in, not entirely sure which years, but after not seeing any on CL at the moment a 78 750 e motor (bored to 860) came up making it an 8 valve, and mine being a 16 valve would that be a bad idea, I'm new to mechanics but am not afraid to make adjustments. Also would my exhaust/carbs even fit? Thanks guys and if not which 1100 years should I watch out for, would hate to trash the bike or part it out if I can keep her running strong!
    Tags: 750, motor, swap
    • bikemtn
      #2
      I am not sure of the 78 to 81 swap. I am in the process of doing a 750/1100 swap. I picked up an 81 1100 motor from a member here on the GSR. I am pretty sure 80-82 1100's will be good for you...maybe an 83 motor too, but not positive. I posted in the parts wanted section on here and that's how I found my motor.

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        • bikemtn
          #3
          I had the same thing happen to my motor. Fixed the spun bearings and got her back on the road.....bam....happened again in a short amount of time. With all the time and money spent I should have done the 1100 engine swap to begin with!

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            • AmazaTX
              #4
              Originally posted by bikemtn
              I had the same thing happen to my motor. Fixed the spun bearings and got her back on the road.....bam....happened again in a short amount of time. With all the time and money spent I should have done the 1100 engine swap to begin with!


              Damn man! My exact feeling! Thank you man I'm gonna do the same cuz I just got new rods and bearings and there was still play in cylinder #2 and #3 so the crank is toast. Would much rather swap the motor to avoid another episode! My ? Is will I have to change the carbs and the exhaust? Thanks man!

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                • bikemtn
                  #5
                  The exhaust should be compatible. The 1100s came with BS34 carbs vs BS32s on the 750.

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                    • Jedz123
                      Forum Guru
                      Past Site Supporter
                      • Jul 2009
                      • 5685
                      • Centeral, Vermont
                      #6
                      The 8V engine won't fit in a 16V frame. The case is longer due to the kick starter. Carbs also are completely different. Just swap to an 1100 and forget it...

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