Starting a ROTAX 503

Jpipe

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I am new to this whole expience.

I am finding it difficult to pull start my Rotax 503. When I get it started, I am tired out and not ready to enjoy the experince.

When it does start it runs very well.

I bought this Van Craft Lightning with a Rotax 503 second hand and was told it had very few hours on the engine and just had not been used. So I set out to clean the fuel filter, single Bing carb (was in good shape ) and replace the air filter. I also fitted a new set of plugs.

I need some sort of starting proceedure to follow.

Any help would be helpful.

Thanks

John P
 

i3 roberto

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Jpipe it'single carb 503??...mmm weird ,,maybe instal a pirmer pump can help you , chec niddle ??,can be stuck , clean carb ,check spark calibration new gasoline ??...and..good look je je
 

BEN S

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jpipe........

jpipe........

install a fuel primer bulb if you don't have one. shoot a spurt of gas into the floats (just a little, like a half of a pump) I can hear it when it changes from air to gas. Start the engine and keep your hand on the fuel primer pump. As it starts to have the RPM decrease give it a tiny shot more of gas to keep the engine running. as soon as it warms up just a bit it will run fine.
Have been using this technique for over 3 years and still enjoy 1 pull starts.
Hope this helps.
Ben S
 

bryancobb

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My old single ignition/dual carb 503 started every time on the 1st or 2nd pull. I HAD to pump the primer knob 3 times AFTER fuel became visible in the lines.
Then when it started, it would die in a couple of seconds If I didn't continue to slowly pump the primer knob in and out for 30-45 seconds of warmup.
 

Doug Riley

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I think that Ben is referring to an inline squeeze bulb (like an outboard motor). It's used to fill the carb's float bowl. If you use one, install a shunt hose around it so that fuel can still get to your carb if the check valves in the bulb hang up (they do). To use the bulb with a shunt installed, pinch the shunt hose closed with the fingers of one hand while squeezing the bulb with the other.

Here in cold, damp Vermont, neither the enricher (choke) lever nor a squeeze bulb necessarily gets you a quick start. In years past, I sometimes yanked 'til my hands bled.

The later Bing 54 carbs have a fitting for installing a true primer. This device is operated by a plunger that is fed by a 1/8" hose tee'd into the fuel line. It is really helpful. The Rotax service centers (Lockwood, CPS) sell primer-plunger kits. Check that your carb has the inlet fitting, though, before buying one.

My start sequence: (1) squeeze the bulb as needed to fill the bowl. (2) Hit the primer plunger a couple times. (3) Pull the engine through a couple times with switch off (but be cautious: pretend it's on). (4) Switch on and start pulling. If it doesn't fire right away, hit the primer plunger again. Better to under-prime than to over-prime and then have to un-flood it!

Hand-starting can be very dangerous. It has killed a few of us, and maimed a few others. Route your start rope so that your pull stroke doesn't take you away from the aircraft (especially the kill switch) OR toward the prop. Secure the machine against a runaway caused by a sudden power surge on startup (yup, that's happened,too; at a flyin some years ago, I woke to the sound of an U.L. plane taking off -- with no one aboard. Fortunately, it was tail-heavy without a pilot and soon stalled and crashed in the woods.)
 

phantom

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starting a rotax 503

starting a rotax 503

here is a trick to start an engine that is not equiped with a primer pump , first blow into tank while blocking the vent tube to pressurize and move fuel into carb, if tank has a vent in cap it is even eaiser as nothing to block, if your fuel lines are not transparent check carb for fuel by removing bottom, then with gas in carb, block one carb vent tube and blow in the other, this will prime the engine and it should start on the first pull.
norm
 

bones

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cant remember, didnt have log books before, but since over 3000
Even easier trick is take off the air cleaner and give a quick spray of "crc" of other lubricating spray with a flamable propelent straight into the carby throat(with throttle open), then start very quickly before the gas blows away, once it warms up stop and replace air cleaner, works a treat :)
Does 2 things, 1 puts a flamable gas in the carb, as well as an oil for lubrication on start up.
 

BEN S

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Doug..

Doug..

I do have a bulb, but was referring to "feathering" the primer push pump handle to move the gas through the fuel lines to the carbs.
I suspect I have an easier time of it as the temps here don't ever go below 50 degrees, and if they did I sure as hell wouldn't be out flying!
Ben S
 

Jpipe

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Hey Guys,

Thanks.
I don't have a primer but I do have a fuel pump driven by the crank case pressure. I have not taken it apart yet.

I have dissassmbled the carbuettor and cleaned it. It did not show any dirt or build up, In fact I was pleantly suprised.

I really wanted the procedure to start to make sure I am doing the right thing.

I will report back after I have tried to start it again.

Thank again for your input.

John P
 

Timchick

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Get a primer plunger kit for it. They are cheap and worth every penny. Purchase a spare primer when you get the first one. The o-rings in them don't seem to last long. My primer bulb developed a blockage in it so I removed it and will never use another one. To get fuel into the fuel lines pull the starter cord a couple times with the ignition OFF. This will allow your pulse fuel pump to fill the fuel lines with fuel. Then I used the primer plunger and squirted 2 or 3 times. Then turn the ignition on and pull the cord. It would start on the first or 2nd pull. If it fires off and then starts to quit you can hit the primer plunger again. I never used the chokes and never needed to.
 

Doug Riley

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If you use any of the "blow into this or that" techniques, don't inhale at any point in the process!

The main fuel pump should NOT be mounted on the block! Mount it on the frame. It'll tend to vapor-lock from engine heat on the block. Mine used to quit inexplicably on hot days until I moved the pump (at the advice of the excellent, late John Potter).
 

drtomcor

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Ok, a real newbie question. I bought a gyrobee with a 503 this fall, but won't be flying it until completing training this spring. I want to run the engine some this winter, and think I would remove the prop for safety. Are there any problems with running it like that? Thanks

Tom C
 

Doug Riley

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Don't do it! These engines need a load to run properly in a controlled fashion. Leave the prop on, secure the machine and the surroundings, and observe the other safety precautions for ground running.

Better yet, have an experienced person with you the first time.
 

phantom

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starting a rotax 503

starting a rotax 503

I run rotax engines without the prop when working on them but before starting you need to turn down the idle rpm and adjust after engine is running or like doug riley said, it will run wild, you have to do the same if you use a clutch on a c box.

norm
 

GyroRon

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Another poor mans way to get a start..... is pour a little raw gas, it doesn't take much, maybe a teaspoons worth and dribble it onto the airfilter, then pull the cord... works like a charm
 

Redbaron

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If your in a pinch you can put some premix in a Windex bottle and shoot it into the Carb with the airfilter off

Another poor mans way to get a start..... is pour a little raw gas, it doesn't take much, maybe a teaspoons worth and dribble it onto the airfilter, then pull the cord... works like a charm
 

Friendly

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All of the methods mention here work. Installing a primer will probably help you to build the most consistent starting habits. If the engine oil mix is not correct , it will be more difficult to run. Old fuel looses its octane and is harder to start. Bear Perkins ran an ad in the PRA Ezine.
He sells a primer kit, if your carb has the brass inlet. He may have a kit for the inlet, but that is better left to someone with experience to install. Good luck, I wish you many happy and safe hours of flying. It best to build good starting habits now, so do as Doug has suggested and block the Gyro in some secure fashion to prevent a runaway

http://www.pra.org/supportfiles/EZineContent/RC_2011_12_Dec.pdf
 

Jpipe

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Jesup,GA
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That sounds like a plan. I can do this.

It took forever to start yesterday. But once started it will fire up first pull.
Today, I turned to fuel on and pulled on the rope 4 times then switched on the ignition.
It fired but took three more pulls for it to catch.

John
 
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