I’m with James on this. I have had better luck leaving fuel in the carb for short periods like this. If you do want to drain the fuel what about running some WD40 or something else through to flush it?
With the engine idling on the stand, pull the fuel line off the carburetor and hold it straight up to avoid spillage.
After a couple of seconds, put your hand by the tubes on the airbox. The engine will continue to idle.
Once the majority of fuel in the carburetor has been burnt up, the fuel mixture will become lean and the engine will rev up. Put your hand firmly over the tubes on the airbox and the engine will stall. If you’re acrobatic you can also push the ignition off button at the same time.
The carburetor will then be dry.
A similar procedure needs to be done for a Briggs 206 at the end of the day, but it will run for minutes on the fuel in the bowl. This can be used to drain the fuel tank by using the pump to pump it into a gasoline can.
Maybe I should start doing that…
This method is better on a 4 stroke than a 2 stroke. Remember, on 2 strokes, they get their lubrication from the oil mixed with the fuel. If you starve it for fuel, you are also starving it of vital lubrication. 4 Strokes have oil pans and lubricate from within.
The actual volume of fuel held in pumper carb is minuscule compared to a float carb. To empty the fuel out, you can rotate the crank to around halfway between TDC and BDC (this opens the both the intake ports and exhaust ports at the same time allowing air flow into and out of the engine), disconnect the fuel supply line from the carb and then while holding the throttle body wide open blow compressed air through the carb venturi (this simulates the natural effect of airflow through the carb and creates the pressure differentials necessary for the fuel to be drown out of jets) . This will draw any remaining fuel in the carb fuel passages out and replace it with air via the fuel inlet opening.
On a float style carb, you can just unscrew the nut on the bottom of the float bowl.
I’ll have to try this sometime. I’m this creates enough of a vacuum across the venturi to draw fuel from the metering chamber. Did you find it opens the metering needle too? Asking since you mentioned pulling the fuel line from the carb.
I tend to agree that running a carb dry in a two stroke is best avoided. There’s (Probably) enough residual oil in the engine for it to be OK, but if you have an air leak somewhere you’re going to have a bad day when that thing revs up as it leans out. Ask me how I know.
@Silverline If you want to expel the fuel from the carb you could use the compressed air method safely. If you wanted to push the fuel out and replace with WD40 you could use a popoff tester pump to push that fluid into the carb.
While this seems like it would work for removing the fuel I’m not sure what WD-40 would do to the membrane and gaskets that are trying to be preserved. It is my understanding WD-40 contains petroleum distillates so i’m not sure what if any preserving would be done.
Agreed, that’s the last thing I’d use. It would be good to get an opinion on the use of ethanol stabilizing additive from the IAME dude on here - @Felix_Rovelli obviously you’d fail scrutineering if you put it on race day but for practice it might help keep the carby good.
Back in the day when I ran modified 4cycles on methanol, we’d “pickle” the engine after race day on WD40. Basically remove the fuel line from the Tillotson carb inlet, then reconnect a piece of fuel line to a can of WD40. Restart the engine and run it until it smoked like mosquito fogging machine. This was mainly to negate the corrosive effects of the methanol has on aluminum. I never had an issue with the carb gaskets or membrane.
I should state that I’m speaking to when you have a fuel with ethanol in it, one might consider replacing it with another fluid.
I think I just live with that I have to do a rebuild every 2-3 hours…
But it would be nice to hear tillotson’s take on this.
The gasket kits you used from Mondokart, were they in a true Tillotson package?