What's the difference between these two carbs?

[Haywire Haywood]

This is for a Tohatsu 2010 MFS6B. They list two complete carbs. A 3R4-03200-0 and a 3AU-03200-0. From the parts breakdown, looks like there's nozzle and main jet numbers that correlate to the 3R4 and 3AU. I'm wondering if there is any difference is the carb bodies and if the differences in jet size is an EPA thing. I've always heard rumors here and there that they ran better before they were leaned out by the powers that be.

thanks,
Ian

 

[pvanv]

3AU032000M is for the 6B. 3R4032001M is for the 6A2. They will interchange. The 3R4032001M is built for an earlier EPA specification, and is a bit richer. The difference is in the carb bodies. We always try to use the 3R4032001M if doing a replacement. For that matter, there is also the 3JE032000M, which conforms to the EPA spec for the 6C.

 

[Haywire Haywood]

Much thanks. I ordered and installed the 3R4 jets (45 and 75) in my 3AU with less that good results. Went back to the originals. Is there a jet/nozzle combination for the 3AU body that will simulate a 3R4 mixture?

thanks,
Ian

 

[pvanv]

No. Again, the difference is in the carb body.