I have a Duromax 440 going into a golf cart. It has a NRracing Honda ported head with small intake port head milled .025, 275 cam all the billet stuff. Advanced to 34 BTDC.
I have a Mikuni 34 mm round slide. What jets do I want to go with. I’m thinking 185 main? It has a 240 in it now. Haven’t started it yet.
First thing I'm seeing is that your carb is a definitely a little small. One or two sizes under the calculation makes for easier tuning than going too big, but more than that leaves power on the table.
√(440)×2=41.95 (40mm)
√(389)×2=39.44 (38mm)
Nobody can legitimately give you an accurate answer to jetting specs that will be correct. At best they can get you into a ballpark within a few sizes to be able to figure it out and dial it in.
There are too many variable beyond the engine and its upgrades that determine your A/F needs.
1. Fuel atomizes differently at different ambient temperatures.
2. Air fuel ratios vary by altitude due to the available ppm of oxygen in the atmosphere to get the job done most efficiently.
3. Air filter (density and breathability) and exhaust (diameter, length, bend count and angles, silencer, spark arrestor) all change fuel needs by shocking amounts.
@Master Hack 's numbers could be a valid starting point, but due to unknown variables and the fact his engine is of smaller displacement, guestimate is about its worth because even two 100% identical engines just will not tune and run 100% identically due to the very small differences you can't see with just you're eyes.
