First.....please no "that engine sucks, that's your problem"

I have a Turnigy TR50HP a 50cc engine with electronic ignition. For the life of me I can't get it to run. I can get it to pop and run for second choked, and maybe 1 out of 50 times it will run for 10 seconds unchoked.

Here's my regimen:

Radio on
open throttle wide
Close choke
rotate engine 10-15 times
close throttle
Ignition on
Flip until it pops
open choke
flip until I want to throw it and the plane over the hillside.

Help?

The carb is a Wlbro WT745
Needles are factory stock 1 3/4 & 2
Ign battery is charged

AAAAAARRRGGGGGGGGGGHHHHH!!!!!!!!!!!!!!!

Is the engine new? Have you ever had it running before? Dan.

Squirt a little fuel in the carb. If it runs the fuel out and quits, it is not pumping. If it doesn't run, verify the timing is 28deg. BTDC.

Have you tried using an electric starter, as some engines when new will pop when choked but will just not start by hand until broken in.

Karol

it is pumping. After I choke it I can see fuel dripping from the carb. I had it running once. I bought it used. How do I check the timing?

Do check the timing, here's my way:
The easy no math timing.

Cut a strip of paper 1/4" x 5".

Rap the paper around the prop drive, back by the crankcase where the magnet is. Overlap the paper then cut with a #11 blade cut though both layers of the paper.

Now you have a piece of paper the exact circumference of the prop drive.

Cut it in half, take one of the halves and cut that in half again, take that and cut it in half also. Now cut it so it's in 1/3 and 2/3 pieces.

The 2/3 piece is how much before TDC the engine should fire, (30*).

Now find TDC by removing the spark plug, then sticking something in the hole, a pencil works fine. Move the crankshaft until the piston. is at the top of the cylinder, you'll find that about 5* either side of the TDC it doesn't feel like the piston is moving. Wiggle the crank back and forth until you can find the center of this piston not moving zone, that's TDC.

Now with a marker make a line across the edge of the prop drive onto the crankcase, it doesn't matter where, just that it's easy to see.

Now turn the prop drive clockwise a distance equal to the 2/3 piece of paper.

Plug the ignition into a 4.8v battery, and turn it on.

Now with the two screws loosened move the sensor off the magnet until you hear the ignition pop.

Tighten the screws for the sensor down, then confirm that the timing is still set that 2/3 piece of paper before the TDC mark.

You may have to lengthen one of the grooves in the sensor mount to get the timing correct.


1.Start the engine, set the throttle so the engine is going 3500 rpm.

2.With the engine running I turn the "L" needle in, it is always the needle that is closest to the engine, when the engine speeds up to 4000 rpm I adjust the throttle to bring it back to 3500 rpm. You keep repeating this step until your engine doesn't speed up anymore when you turn the "L" needle in.

3.Turn the "L" needle out 3/16th of a turn.

4.Open the "H" needle 2 turns out, open the throttle all the way open. Now slowly turn the "H" needle in the engine will increase in rpms. Turn the needle about 1/16 at a time, when you get no more increase in rpm the "H" is set properly.

5.Set you idle speed with your throttle trims, it's best to take the idle stop screw completely out, you should have it so the idle is correct with the trim in the middle, and the low trim kills the engine.

6.With the engine running at the idle speed that you fly at you should now be able to snap the throttle open and the engine quickly speed up. If it just dies, turn the "L" needle out 1/16th of a turn, repeat this step until is quickly speeds up. If when you snap the throttle open it stumbles then speeds up turn the "L" needle in 1/16th of a turn until it cleanly and quickly speeds up.

7.Close the hole or notch up in the choke plate, I'll post a picture of what I mean, I do it with soldiering the hole close, some use glue or a bolt.

After you modify the choke plate the way to start the engine is:
a. Close choke completely.
b. Open throttle half way.
c. Flip engine with ignition on until the engine coughs.
d. Take choke fully off.
e. Set throttle just above idle, flip until it starts, usually 3 to 5 flips.

Here is an exploded view of the carb. Make sure the diaphragms are in the right position.
http://wem.walbro.com/walbro/product...m=WT%2D745%2D1

Use this to check the timing.
http://www.youtube.com/watch?v=GBXFpxWg7vY
Dan.

Open the throttle to about 1/8 or 1/4 open. It may be set to shut down with the throttle closed, especially if the idle stop screw is removed as it should be. My Echo will not run no matter what with closed throttle, but roars to life with about a 1/4 open or so. Just a thought.

Not just spark time on this one,check rotary disc.

Prebres,

To me, it sounds like your engine has flooded. Pull the plug, spin the engine over a few times to clear out any excess fuel
I would suggest a few steps to isolate where the problem comes from.

1. Pull the spark plug, make sure the gap is roughly the thickness of an Xacto #11 blade, then put the high voltage cap onto the plug (outside the engine.). Plug a 4-cell NiCd battery directly into the ignition (no switches etc) and flip the engine a few times. If you get a healthy spark, you know you're OK there.
Now to test fuel draw
2. Put the plug back into the engine and press the high voltage cap firmly onto the plug. Make sure the spring goes right over the hex area of the plug.
3. Set both needles to 1 3/4 turns out.
4. Choke on, 1/4 throttle, ignition on and flip a few times till the engine kicks. Keep an eye on the fuel line to see when the carburettor starts pumping. You will know when you have fuel in the carb because you will be able to smell it
5. Choke off, throttle a few clicks above idle and flip again.
If this doesn't do the trick, check the carb membranes

+1 on sounds flooded.
clean plug
needles 1 1/2 out (if low needle is out lots more it will flood and not start)!!!!
throttle couple clicks up, ckoke on flip till coughs
choke off,throttle same,flip,
let us know

The description of the starting procedure in the first post says why it's not running. The engine is being flooded every time an attempt to start is made. WOT and choke on for ten flips before arming the ignition?

Try throttle trim open 1/2, throttle closed, ignition and choke on, then start flipping till it pops.

I agree with T.O.M. Most gas engines should pop with the ignition armed, choke on, throttle between 1/4 and 1/2 in 3-5 flips.

When the engine is flooded, another way to clear it is to arm the ignition, put the throttle to full, and then flip it. The engine won't generate enough pulse on the carb to further flood the engine, but the extra air will help the excess fuel burn. Make sure the plane is well restrained.


Brad

Tired Old Man........you got it. Starts now. Thanks everyone.

Glad it worked. Better yet, the solution was simple.

ADDEDTIP>>>

After flying or just running your engine....shut the reciever in airplane too off position when you have the engine at a smooth idle speed. Then the next start-up, the engine (withrec &radio off)will start very good at thatRPM setting. In other words the right amount of throttle has a lot to do with good starts. Capt,n

That depends highly on the servo used.

Tom....you are correct....you want the throttle at the exact idle position on re-start. You need a servo that stays right were it was on reciever shut-off. Tom is on the Ball....Take Care Tom. Capt,n

Yep, the throttle spring will move my HS-7985MG when the power is turned off leaving the throttle butterfly completely closed. Oh well never had any trouble with starting anyway.

Ahhh, the advantage of a digital. Once the power is turned off there's no further hold from the servo so it follows the weight or resistance of what it's connected to. OTH, once the servo is powered up again it will go pretty much exactly to the position commanded by the TX/RX. If that position happens to be in the same place as when the servo was powered down, the servo goes there with 100% of it's rated strength.

However, an analog servo is sort of unsure of itself most of the time, has a lower resolution which makes finding the last position and center considerably more difficult, and has about a 7 degree variable built into the gear train at the control arm. It achieves rated torque only after traveling though about 60% of its rotational distance. It will try real hard but it has soooo many performance deficiencies built into it and those are hard to overcome.

Man, not to be rude, but how tough is it? Crack the throttle, and start the engine!

AV8TOR

well after running for a day. It now will not even pop. I am thinking the ignition is faulty.

Well, if you are pretty sure it is neither flooded nor too lean to start, then the ignition could be suspect. If you are using a 4.8 volt battery pack, try a 6 volt pack. I have had marginal ignition systems work when trying that trick. I have had ignitions that would show a spark when checked, but not want to start the engine until using 6 volts. Bill from CH told me about the 6 volt trick....

If that Turnigy came with the "blue box" ignition, they are known for failures.

AV8TOR

I had an RCexl that came with a DLE that worked good when new and then slowly got harder and harder to start and sometimes would just die at idle for no reason. (Just like you switched the ignition off.) I tried the 6 volt thing and it never acted up again. Wore the engine out on it.

It is the blue box ignition so I ordered an RCexcel ignition. I also got a carb rebuild kit, just to be safe. Just hope the ignition gets here before I leave for the DOGS!