Re: 1939 Neptune 2A39 Won’t Keep Running

[slim60]

If you think the carb is OK I would start by pouring some Seafoam into the cylinder to clean the gunk off the rings. Let it sit overnight. Maybe two nights. Mix some 8:1 gas. You can go back to 16:1 later. Remove the prop and muffler or exhaust tube. I just went through this routine with a ’41 opposed twin. You may have to spray fuel into the carb the first few times. When it runs let it warm up then shut it off to cool down. Do this five to ten times, then install exhaust. If it runs install prop. If not, go back. This is how it was explained to me. Your arm will get sore and this may take a few days, so good luck.