Anyone ever try removing the the butterfly screw and soldering it on? Shure you would have to melt the solder if you wanted to pull the shaft but it would flow better without that screw in the venturi.

dkf wrote:With the carb body acting as a heat sink, it would be VERY difficult to get a good bond between the butterfly and shaft.

If it looked good and in reality was just a shiny low penetration joint, swallowing the butterfly at 17K+ is going to hurt ... A LOT !!

Scott wrote:
If it looked good and in reality was just a shiny low penetration joint, swallowing the butterfly at 17K+ is going to hurt ... A LOT !!

:clapping: Scott is absolutely right. And if you mess with the screw in the butterfly, you will most likely end up with the same results. :diablo:

theres no screw and blade coming out of mine... i epoxy the blade to shaft, then epoxy the screw to blade and shaft. Ive yet to have one loosen up or come apart. Far too many bone stock carbs are having the screw loosen up and not let carbs close to just take them out of the box and bolt it on and run.

I am going to try this carb mod, has anyone done this or run the 813 carb with any results

I have modified my Zenoah 260 the rpm with this engine in my sprintcat 42`` is 18500 with a PS 7016/2 ss prop.Speed with a PS 7018/2 was 103 km/t.
I have tried several types of Zeonah carbs and the 813A works best i got almost 800 rpm more with this carb than with a modified 257.
I also found out that there are no gain by soldering the butterfly plate i just grind down the head off the screw as much as possible and cut the bytterfly holding screw (its to long)
The most inportant is to line up the carb with the isolator plate and inlet port.I have also instaled zero drag zeals.And lightened the piston.I also driled four holes just below the piston ring to get better flow.And raised the exhaust port and modified the transfer ports.

My homepage.
www.mhrcboats.piczo.com