After you have checked out your ignition with a gap tester,using the starter but NOT starting the motor maybe this will help:

I had a 12 HP Sea King and later a RDE18 that did not want to start or run. They would fire then run terrible. Solution was that the carb needles needed more packing rings. Often it takes 3 rings per needle. Air was passing the needles and the motors were running lean. I would try one or two more packing rings to each needle and in tightening the packing nut assure that the lock nut is down against the packings. See how deep the packing nut is into the threads. Not too shallow, you do not want to strip the carb body threads.

WRT the starter it sounds like you need to oil the Bendix drive. I have found on four different RD18s that starter drive always retracts regardless of whether the motor starts. Fleetwin has way more experience and is far more knowledgeable so maybe I am wrong but that is what I have seen. Test it without starting the motor but with plugs in.

BTW if no one has mentioned it, do not start the motor without water to the pump. Running dry will destroy the pump impeller.

Mumbles wrote:

The RD and Big Twin carbs don’t have a seal or gasket on the nozzle. It’s a machined fit.

Here’s a parts manual for you.

To be more specific, the RD & Big Twin models with an adjustable high speed needle did not have, nor need a nozzle gasket because any leakage there is compensated for by adjusting the needle. On the other hand, later models with a fixed high speed jet do need the gasket because you can’t compensate for leakage. Summing up, it doesn’t really matter whether or not you put a gasket in the adjustable ones.

Mumbles – I’m sure you are right about how that seal ended up in my carb. I put in a new seal only because I found one in there. And you are certainly right about how thirsty these motors are – that seal won’t make any difference!

The carb rebuild kit I got had a thin cork gasket included which is what I used on the nozzle. It was much thinner than the typical nozzle gasket. Now I know why. Here’s a pic of mine. I didn’t have any trouble reassembling the bowl and carb body with this gasket in place.