81 CB750 F won't start 1 and 4 have no spark

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81 CB750 F won't start 1 and 4 have no spark

CBNewb84
I've been thinking I had carb issues with this bike for a while. Had a buddy who's a mech clean them and got them back on today. The bike still wouldn't fire up, so I pulled plug #1 to check if there was gas in the cylinder, which there was. Just for the heck of it I checked the spark and got nothing. Swapped to the #2 wire and got spark, so I checked #4 and same thing, so looks like there is an issue with the left side ignition. Is there anything I should check first before replacement? The bike ran a little over a week ago before we cleaned the carbs, but it had been sitting for a long time before that. I checked the wires on the back and everything is tight.

Thanks for your help. This project has me pulling my hair out.

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Re: 81 CB750 F won't start 1 and 4 have no spark

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If you download the factory service manual from the link at the top of the home page here, you will find detailed instructions on testing the coils, and ignition system. However I would bet that something got unplugged when you were removing/installing the carbs.
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1976 CB 750-A X 2
1977 CB 750-A X 4
1977 CB 750-K
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
South of Eden (Kansas City MO)