Re: First Water Choke

[rvpapasso]

Frank, I may have a theory on why many people with the automatic water choke set it to manual for starting based on my experience with it. If you understand how the choke works and where it is positioned in the carb relative to the throttle butterfly and the main jet my theory may have credence.

Typically in a carb with only 1 jet, main jet, “choking” is to pull raw fuel out of the main jet and into the engine. The maximum amount of raw fuel will be pulled with the air inlet of the carb blocked and no restrictions to air flow between the main jet and the combustion chamber.

The choke provides the blocking of the carb air inlet. However if the throttle butterfly is closed and not open there is a restriction of the airflow and not as much suction is at the main jet to pull raw fuel out of it.

Due to the vacuum pull-off with the water carb the choke will flutter some due to some vacuum produced when the engine is pulled through. This flutter does not allow the choke plate to completely block the air inlet reducing the blocking action of the choke. This is most apparent with electric starting.

To get max suction at the main jet the throttle butterfly has to be opened as far as it can be in neutral. With electric starting the mercury switches sometimes are not set properly to allow the starter solenoid to be energized at max throttle in neutral.

Both of the above combine to make a hard starting engine for a cold start. The fluttering of the choke plate and inability to have the throttle opened as far as possible reduce the amount of fuel that can be pulled from the main jet.

My electric start engine was hard to start on a cold start at the beginning of the day due to the above. Slightly tweaking the mercury switches to allow starting at max throttle in neutral resolved it. Converting to the safety switch under the flywheel to eliminate the mercury switches will alleviate the problem entirely.

As for manual starting the engine does not turn over as fast or continuously as the electric starter will do. Any flutter of the choke plate is a real detriment to pulling raw fuel. In the occasion I had to manually start the engine I always had to manually set the choke, open the throttle as far as it will go in neutral and pull it over a few times with the ignition off. Then bring the throttle back to a fast idle position, turn off the choke, ignition on and pull it through. It started every time.

My opinion is the water choke was really designed for electric starting engines and the convenience of not having to leave the driver’s seat to start the engine. For manual starting you have to be back at the engine and manually operating the choke is the best way and not relying on the automatic choke.

Once started if you have the thermal warm up set correctly the engine will run smoothly without lean sneezing.

The above is my experience with simple carb engines. The same rules apply to cold starting with my 1943 Harley. As you can imagine if you don’t get the starting drill correct you will have a heart attack jumping up and down on the kick starter like a monkey on a pogo stick. Same starting drill; close the choke all the way, open the throttle all the way, ignition off and a few prime kicks. Then choke off, throttle cracked, ignition on and a swift kick and it starts on the first kick every time when cold.

Can’t say for sure if my theory is correct but trial and learning (i.e. error) has found it works.