Turbobeaver

Hi all,
Would like to find out about the pro's and con's of using a primer bulb system on a Homelite 25/30 for model aircraft use.I know it's not necessary to have one to start the engine and some guy's just pinch off this tube on the carb and solder it closed,but how much harder does it make the engine to start with out one?Should I keep it or lose it guy's?Love to hear your comments on this.

Antique

My Feedback: (4)

Unless you run the gas out of the carb at the end of the day it makes no difference at all, it's there only to fill the carb from the tank...You still need to choke the engine...

Turbobeaver

RCIGN1,
Without the primer bulb on the carb,how much flipping of the prop does it take to get gas through the carb,especially if it's been sitting for a while and has lost its prime.You would be relying totally on the carbs pumping ability to deliver fuel to the carb from the gas tank and also remove any standing air that may be in the lines.I understand that the principal behind the primer bulb is not so much for priming the engine but rather to remove air from inside the carbs fuel line and passage ways and replace it with fuel so when the engine starts,it will keep running.It also saves you from having to crank or pull yer butt off to get it going.Am I understanding this correctly?

Is it a common practise for most people running gas to run the carb dry after the end of each flying session?I would imagine this would prolong the life of the pumping diaphragm and reduce any chance of gumming up the internal fuel passage if you did this.With that said,how many of us drain our weed wackers and run them dry after each use?HMM!!

captinjohn

Turbo...you got it right on. I had a boat with a Homlite 30cc engine. Got a 30cc for my airplane also. You can see the bubbles dissapering as you use primer. Better than a choke is too learn how much of a prime(squirt fuel in carb) your engine starts best on. After it fires up you do not have too reach for the choke and get your hand or arm in the prop arc. Also having the idle mix a little on the rich side will keep a engine going when its still cold. Capt,n

Antique

My Feedback: (4)

When you choke the carb with your thumb or a good closed plate you're not using the carb pump, you're getting the full crankcase suction...Way better than the carb pump..The primer bulb does the same thing....It works when the choke plate doesn't close off the venturi entirely like your thumb does..If you have a tygon fuel line you can see the fuel coming into the carb 2 inches or more with each crank rotation...Or just rock it back and forth around TDC...
Very few fliers I know, myself included, run the carb dry at the end of the day..

Antique

My Feedback: (4)

Everyone in my group, myself included, runs the carb/engine dry after a days flying. At the end of the day, pump the tank dry and run the engine until it runs out of fuel. None of the guys I know ever use the primer bulb, just choke it with your thumb over the velocity stack till your thumb gets wet, crank it up and your good to go. Never had any problems with this procedure.

captinjohn

Yes that is a very good way to start. Seems like a lot of extra time spent running them dry. May be good safty pratice though. Less gas in case of fire!!!!!!!!!!!!!!!!!!!

av8tor1977

My Feedback: (6)

With my glow engines, I definitely run them dry, then add some after run oil due to the hygroscopic and corrosive effects of methanol. On my gassers, I don't bother running them dry unless I think they are going to sit for a long time and the fuel might go bad and gum up the carb. If you do run them dry, I suggest squirting some after run oil, (whatever oil you put in the gas would be fine), into the carb and turning it over a few times.

Take care,
AV8TOR