Good afternoon.

I have now converted a Saito 82 4st glow and a Os 62 4st glow to Gas.
First, please note that it is absolutely, completely and enthusiastically worth it !

Now, my set was made with Brutus (Bert) parts and help.
God did I learn a lot about engines !

I went through all the mistakes and mishapps possible, but now it is a delight.

I would like to share here with you folks my learning curve. If you do it exactly as I say, you will have an immediate success and you will know WHY.

Converting to gas from glow is changing a carburation setting from extremely voracious to extremely sparse: 125 cc glo will last some 15 min, 125 of gas will last more than one whole hour !
Cost of gas is peanuts, cost of glo fuel is platinum. No more killing your bearings with gas.
This sparsity comes as a now very thin flow of gas you will use, which has to be mixed very precisely with the exact amount of air. That is done by inserting in the gas line a tiny solenoid valve which will regulate it very very precisely. It is powered via a tiny processor fed by special 'valve' curve from the Tx, see that down under.
Glo will take it +/- 6 clicks, gas will take it +/- 1 click.

That means you have to use a very good gas feeding line! I will give you the exact list of components, please stick to it !! it will save you hours !

You will need:
* a special tank made for gas, 125 cc is perfect.
* a tiny tank which will catch any crap coming from the pressurisation line. 50cc is plenty, I use a pill box, 20cc big. Check for proper airtightness.
* Those yellow special piping for gas. I found mine on Amazon for a few euros the 3ms. Take both 2.5mm and 3 mm sizes.
* Bert's solenoid set, which is a gas regulator with a tiny computer device (totally ready to use, no need to program it yourself) in it. Take his, I made mine but it died after a few hours. His is flawless and tiny. Cost is peanuts too.
* the usual ignition set, please also take the timing device which will allow precise installation, and the rpm meter.
* a special FELT tank clunk. I have tried the others, they let you down. The felt one is the best and only. You can find it in your usual garden equipment store.

You will be fiercely hunting for any bubbles in your feeding line: Using this yellow piping makes it easier since it sticks to whatever it is connected to.
Do not waste your time with any type of other piping stuff !
-Piping diameter: Bert supplies his set with 3 mm outlets. Use the 2.5 mm one you bought, I had air leaks (bubbles) with 3 mm.
-Use some standard silicon piping for the pressure tap, The yellow would melt.
-Do not even dream of using this silicon piping for the gas line: it will not only dissolve (!) but also let a ghastly goo to pollute your carb !
-Isolate your carb from the engine heat with a piece of plywood or carboard shield.
-Loctite your screws to the engine, if not they may get undone because of the vibration pattern, which is harsher. The engine does not vibrate more than with glo but those vibes are harsher.
-I cleaned my carb with hot water and soap in a ultrasonic bath because I had to get rid of the goo there was everywhere.
-Have short gas lines without big bends. Remember we are dealing with minute flows now !

Now, the start.

Please understand you will have to let your engine run for at least 6 hours (this is about 1 liter of 8% mix oil in gas), in order to get rid of any remains of glow combustion and proper breaking in. It will start to run well after those 6 hrs. Not before.
You will need an electric starter in the beginning.
The idea is to start the engine and adjust the throttle as well as you can. Remember, one click is a lot.
On your radio set, you will have to program a throttle curve and delay (delay is from full to 0 in 5 seconds), because it must be gentle. I will let you further down see which one I use with success.
Bert's supplied set is a tiny thing you connect to a special channel on your TX, to which you feed a 'valve' curve. This is to reduce in 9 steps the gas flow to exactly what is needed for every step of engine speed.
So, 2 curves in all: a 'Thr' curve on Channel 1, a 'valve' curve on Channel x connected to the valve set.
The pressure tap is crucial, it is the one which will push the gas and air to the carb. The flow is so minute that without it it won't work.
When those are connected you can check it works by hearing a soft clicking which is the noise of the valve working according to the valve curve.

What adjustments will you use: with glo, you start with some 2.5 turns of main needle, here start with 0.5 turn.
Do prime your carb well enough to eliminate bubbles and apply the starter while gently moving the Thr stick.
At one point it will start ok because your Thr position corresponds to a needle adjustment which corresponds to the proper valve curve point.. Let it heat up there for at least one minute. It will be quite poor but will run. Target a start at 50% Thr stick.
Then try to rise the thr. Your engine will disagree, then you add +/- 1 click. You will see if the engine dies or accelerates. It starts very easily (better cold), so redo it if needed. Let it run like that for some 15 mn then go on rising your Thr stick, everytime +/- 1 click.
When you are more or less at full Thr, let it run like that for some ... hours, to break it in. Total consumption: about 1 liter. Gas is mixed with 8% synth oil.
When it is done, you will notice that:
* the engine compression is now excellent
* the adjustments are frank and easier every time.

It is now time to start gently and slowly lowering the Thr and adjust each valve curve point on your TX for the best engine speed and response: for ex if your Thr is down to 50%, adjust the 50% valve curve point. These adjustments are done +/- 5 % maximum, let the engine adapt. Don't forget your are letting a tiny flow of gas in !

Idle adjustment is easy but ONLY at the end of the whole process: do not try to get it at the beginning, it will change and not stay steady being much too fast in the beginning, before everything sits in properly. My Saito idles at 1850 rpm +/-.

What happens to the Lo needle of your carb ? nothing, it is replaced by that wonderful little solenoid valve. Forget about the Lo needle.
You will never have to re adjust your valve curve once it is done. You may just wont to fine tune it at some point.
Please note that accelerations are medium easy because it breaks a pressure balance in the carb and needs a few moments to adapt (thus the Thr delay). They get better with time and breaking in. When they are fine, your engine is optimal.

My 9 points curves:
THR:-100; -85; -67; -50; -30; -5; +24; +56; +100
Valve: -62; -63; -61; -55; -42; -22; +2; +28; +59 THOSE VALUES YOU WILL HAVE TO ADJUST for your own engine ! they are only a starting point.

I now would like to thank Bert (aka Brutus) without him I would never have succeeded. He is probably one of the best engine engineers you can find and he spent so much time explaining me all sorts of things until my final success that I consider him as the King ! Thanks also to Raleighcopter, who is the valve's controller set designer: tiny, reliable, absolutely excellent. Makes life so easier and you won't have to question it.

Have a good time !
Billy