I dug out some of my other MVVS engines. Here is my MVVS 6.5cc Quickee 500 racing engine. I think they stuck on the MVVS carb intended for the 10cc engines on this one. As it has a really big bore in it in comparison to the other 6.5cc engines. But I was too lazy to measure it though.










Here is another one that I have:




You can see the smaller bore carb on this one


You can see the smaller bore on the newer model 6.5cc blue head engine here too