Hi.

I have an OS LA .65 engine ( [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXLL61]see it here[/link] ) and an electric starter ( [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXL396&P=ML]here[/link] ). I prime the engine and put the hot shot on the glow plug. 1/2 open throttle. Then I put the starter on and crank. However it takes about 30 - seconds of continuous cranking for the the engine to start. Even after a 10 minute flight, it's the same problem.

I've been told it should only take 1-2 seconds of turning. Is what I'm doing harming the engine? What could the issue be? The glow plug is brand new and glows nicely. The engine has been flown perhaps 20 times (so it should be broken in).

Just how much are you priming it and how? What method? Are you pouring fuel in the carb or choking it and drawing fuel through the fuel line?

I find best results when (with glow heater off) I open carb fully and put my thumb over the intake. I then run the prop through by hand until the fuel from the tank reaches the carb inlet nipple. I then give it 2 more flips. Close the throttle to just a little above idle setting. Apply plug heat, wait a few seconds for the plug to heat up (3 is usually plenty) and apply the starter.
Should now be running.

Are you hurting the engine? Probably not but remember the oil is in the fuel so never turn it over dry. Proper tuning is also important.

I put my thumb on the muffler exhaust hole and turn the prop until fuel reaches the carb. Then I'll turn the prop 2-3 times with my thumb removed from the muffler exhaust. Then I put on the glow plug and attempt to start.

???????

Be sure the carb is full open during priming and keep the thumb on the exhaust for those last 2-3 flips. You're probably getting fuel to the carb but not through it.

I thought you were not supposed to prime with electric starters because you risked hydro locking the engine? Is it possible you are flooding the engine by priming it (or at least it has way to much fuel in it) and it is taking a few seconds for it to spit out enough of the fuel to come up to the right mixture?

Yes, I suppose. But should it take up to 30 seconds of using the starter to correct the mixture? If the prop is spinning with the starter, I would think that the engine is only slightly flooded and wouldn't need much to correct. I'll try the suggestions this weekend and see what works best. I'm tired of looking like a newbie at the field! [:@]

He's hand flipping it during the priming. He wouldn't be able to turn it over easily by hand if it were going to hydraulic lock.

He's been priming until the fuel JUST gets to the nipple on the carb. Big engines with the carb half open do not draw fuel well when being motored by the starter, not enough vacuum.

I disagree. He said he was flipping the prop 2-3 times AFTER the fuel got to the carb, which is what I normally do when I am hand starting my engines. I can usually give a quick flip with the chicken stick and they fire right up after being primed.

I have the same propblem with a LA25. Had several of the other club members try and still have to crank the crap out of it. Dead sticks every landing. Replaced tank and lines, pulled apart and sealed everything.
I ended up ordering a new high speed needle, let ya know if that does it

You're right about the flips, an oversight not to mention it although I had read it.

He still is probably not flooding it and definitely not experiencing a hydraulic lock.

Since YOU do it the same way you should realize these things.

foosball:

At 1/2 throttle or greater the fuel may tend to siphon back into the tank fairly quickly.

I normally prime the engine and then bring the throttle all the way down, before hitting the engine with the starter.

It takes much longer for the fuel to drain out of the carb this way.

So should I only cover the muffler exhaust hole until the fuel reaches the carb and the attach the glow plug and attempt to start? Forgoing the 2-3 flips after the fuel has reached the carb? I tried this once I believe. The fuel reached the carb and I put the glow plug on, then I noticed the fuel had retreated back toward the needle valve. Should the fuel line be full and stable before starting? Or does there just need to be a little fuel in the chamber and carb?


EDIT: Thanks opjose - that answers my question.

1/2 throttle is way to far open for starting. Throttle set at idle or slightly above should be plenty for starting.

Brad

Yup like he said...

Closing the throttle down, also reduces the aperture that permits the fuel to siphon back.

That means it runs back from the carb at a much slower rate giving you time to get the engine started.

You also don't really want to start a plane at higher throttle...

A high idle will do if you are unsure of the engine, and then at mid to low idle once you have the engine fully tuned up.

I fill my tank with a syringe and always put 2 or 3 drops of fuel in the carb, turn it over once or twice by hand then use the starter , rarely takes more than a second or 2 to start...Rog

If the tank is at the correct level then fuel shouldn't run back from the carb unless it's a tail dragger that sits very nose high. Priming an engine involves more than just getting fuel up to the carb, a small amount of fuel has to get inside the engine and then get spread around up into the cylinder where the plug can fire it. It's a bit of an art to get it perfect but a little practise will soon have the engine starting on the first flick or bump with a starter. Usually 3 or 4 turns of the prop after fuel has reached the carb (at full throttle) is enough to start spreading it around by giving a few quick flips of the prop until the engine begins to sound "wet". You'll know the engine is ready if you connect the glow ignitor, hold the prop firmly and turn the prop slowly over compression. The engine should fire and kick the prop back against your hand.

With any plain bearing engine like the LA you must be sure there's oil around the steel shim thrust washer behind the prop driver when you use an electric starter or you risk damaging the crankcase. With hand starting this doesn't matter.