Best carb combo for 750 big bore kit and Shell #1 cam?

[zrx1100]

I had the VM34 on a 750 kit bike and they seemed to work OK. They had been set up by a previous owner so not sure of the jetting. Since then I have built a number of bikes, and never had any problems getting the stock BS38’s to function properly. A stock bike with open pipes needed one size up on the pilot and I left the mains alone as it ran fine. A 707 kit bike with pods and open exhaust, 1 size up on both jets and I got a nice colour on the plugs, but possibly 2 sizes up on the pilot might be better as I have a tiny hesitation off idle.

I had good experience with bs38 as well. On the jetting I found that exhaust/intake combo affects jet size hugely. I went from 135 to 152.5 on the main by changing from commando/stock air box to open cone mufflers/Uni pod intakes to maintain AFR in the 12s. The pilot and the needle hardly changed

 

[Kevin Werner]

I was told by the gentleman from Brazil that VM34s flow much better than BS38s. Both are easy to rejet as you are tuning your build.