Would have guessed a Mikuni and that appears to be the case. Found a chart that has some information but oddly it doesn't list a 440 F/A for 78. Only lists this engine for 77. In any case, the carb listed for 77 would probably be fine.
Year | Model | Carb | E-Ring Position
(From Top) | Air Screw
(+or- 1/4 Turn |
1977 | TNT 440 F/A | VM36-53 | 2 | 1 |
Have to confess, I don't know what the "53" amplifier means (but I'm sure someone does).
This chart leaves out some key information: main jet size, pilot jet size, needle jet size, etc. If you ask 50 people you will probably get 50 different answers but you might get a feeling for what most people are running. I got lucky on my Cyclone; ordered a carb from Dennis Kirk and it's run perfectly for three years with the jetting it had when I got it.
One other thing to consider is the type of choke setup. If the original cables are there, the choke cable should tell you whether it was the round plunger style (preferred in my opinion) or a lever style. Mikuni's can be bought with either configuration. Replacement carbs are pretty reasonable, maybe in the $90 - $120 range.
If I ever run across some jetting info, I'll pass it along. Good Luck!!