Hey guys, I got a 440 Duromax engine. Billet flywheel, Billet side cover, Billet connecting rod. 275 Dyno cam, 55 lb valve springs. NR Racing Honda 390 Head with 40 mm intake, 38 mm exhaust stainless valves, head shave .060, (this NR Racing head has the small intake port for low end power. The port was matched to my intake manifold) 1.2 ratio roller rocker arms, chrome moly cut to length push rods. + or - 34 BTC ignition timing. Mikuni 34 MM round slide carb with a 15 low jet 210 main jet. Float set at 22 mm. Auto lite plug. Engine fires right up. Runs strong. You hit the throttle and no faultering, it just takes off. But after a bit of running it mis-fires once in a while at cruise RPM. The plug gets black right away. So I say it's running too rich.
Any tuning advice? Should I go even smaller on jetting? It is a gravity fed fuel tank. The bleed screw or whatever it's called is 1 turn out from being seated. I can't read the number on the emulsion tube but it starts with a 159. The needle in the slide is set in the center slot.
Any tuning advice? Should I go even smaller on jetting? It is a gravity fed fuel tank. The bleed screw or whatever it's called is 1 turn out from being seated. I can't read the number on the emulsion tube but it starts with a 159. The needle in the slide is set in the center slot.
