Just looking on some info on the 257 vs the 813a in regards to overall peformence and what you boaters prefer and why. I do have them both and am wondering which one to put on my TOXIC AL full modded jen.

Bronco - The 257 is the carb most everyone uses, modified is even better, it has a single inlet usually set up for using an IV bag as your tank, the 813 is also a good carb it has the primer bulb, which you really don't need, and has a fitting for the fuel inlet and return line for a gas tank, also the 813 has an acellerator pump circuit.
Anyway for me and Al's motor go with the 257

813's even tho they are provided by zenoah as there performance carb, just won't hold a stable high needle setting relative to other carb choices. So frankly would leave it on the desk as a paper weight.

257's while the generally accepted standard of performance carbs, it works great so long as the low end is kept fairly rich. While this setting makes the carb work well, it is a crutch setting masking a low speed transition mixture that is too lean !

Testing a LOT of carbs threw many years goofing around with RC gas boats, the absolute BEST carb was the WT-488 ... it is NLA sadly but has a replacement, the WT-771 which is factory carb on the CY/SIKK 25.4 marine engines.

* But as you have asked ... use the 257 :dance2:

Thanks Guys
I would also say the sikk carb is a great carb. Ive got one and it performs flawlessly and at the moment is out doing my bonzi 2 mod with 257 that has issues at the moment. Very hard to keep running in the corners unless its full-on the sikk has no issues. Im running IV bags in all my boats its the way to go thanks for the info Scott you've been a great help.
Bronco78

Just thought id throw-in a pic or two of my sikk.