Recently, I finished restoring a 1971 CB750 K1 and I think it turned out great but I was having one issue with it. I thought I would share this to maybe help someone having a similar issue. HondaMan helped me solve the issue, so I want to thank him for his input. The bike ran perfectly until I gave it full throttle and then it would begin to sputter, cough, loose power and basically run badly. To solve this, I ran the bike without the air filter and the problem did not occur. This indicated the the bike was running too rich. I had some new 112.5 main jets, so I replaced the 120 main jets with 112.5 main jets and the problem was solved. The bike now runs as good as it looks. I have three of these K1s, but this one may be my favorite.
