Hi, I hope I am posting in the right place. If not I apologise.
I bought a 77 CB750 in December last year and I have had the Carbs on and off more times than I care to mention!! cleaned and poked and prodded and adjusted in a continual cycle trying to get them running right. I have now got them running a lot better!! I have gleaned a lot of information and help from this forum and I thank you all.
The last time I had the Carbs off I had another look at the accelerator pump as the engine was bogging on quick throttle action. In a moment of clarity I held up the pump diaphragm up to a light, looking for holes. I spotted that there was no hole on the inlet tab to allow fuel into the pump. This I assume to be a manufacturing fault. I created a hole using a needle and increasing the hole with larger diameter wires until I achieved the same diameter as the outlet tab. I put it all back together and put the carbs back on the bike and Eureka!! Problem solved. I hope this post helps someone in a similar predicament.
Loving my CB 750 and this Forum. Incidentally, the bike was imported from Wisconsin to the UK. There is a key ring on the keys naming the bike shop that must have supplied it. I will take a photograph and post it maybe someone knows the business or the bike. it would be interesting to find out more about its history and ownership.
