Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Bonjour Tom,
He is the instructions manual, It does not help a lot. Besides this, I did not touch anything about compressionbecause I have no knowledge on this type of engines and no appropriate control tools... To you opinion, the miing is poor, I will try to open a little bit mor the mixing needle.

Bonjour Ade,
Good idea ! I had already added a drop of oil in the gas but will add a little bit more,because, as noticed by Tom, there is not too much smoke.

Besides this, please note that this engine is a 1,6 cm3 and not a 2,6 cm3, Jin has to progress in arithmetic calculation 

Bonjour,
This video confirms that, even if the compression is very weak, although it improves a little with the rise in temperature of the engine, everything is in the VERY precise adjustment of the carburetion. I touched the small secondary screw on the side of the carburetor to close the throttle a little. It is a millimeter or less.

Bonjour Raphael,
Quick question, the carb looks like it is based on an RC model engine carb, these usually have two mixture adjusting screws.  The one you are moving is the main jet, this usually controls 2/3 to wide open throttle and then there is a second screw (the idle adjust) which is usually situated in the centre of the throttle arm.  If you see an adjuster there then i think maybe the low throttle is too rich and to compensate for this you screw in the main jet, so now the main jet meters the fuel at low throttle, BUT when you open the throttle the engine dies because the main jet is not supplying enough fuel.
May i suggest, if you see a low speed adjustment screw, open the throttle wide open, crank the engine and at the same time open the main jet until the engine fires/runs  (the high speed adjustment should be done first) once you get the engine to run at full throttle then gradually close the throttle and adjust the low speed needle until you get the best low speed running.
I hope this helps, i'm only guessing based on experience with RC aeroplane engines.
Best wishes
Ade

Bonjour Raphael,

Not quite,
1. First we set the main jet, this is the silver one by the fuel inlet pipe (ignore the other jet for a minute).  Open the throttle fully and adjust this jet until the engine runs at full throttle. 
2. Then reduce the throttle until the engine starts to run badly, this is the time to gradually adjust the slow speed needle (the gold one in the centre of the throttle arm) until the engine runs nicely.
3. Repeat step 2 until you can get right down to a fast idle speed.

I have a feeling this engine will overspeed at full throttle with no load,  if this is true then keep adjusting period very short, we only want to find a baseline setting for now.

For this type of carb in an RC engine the main jet setting is critical to provide full power and keep the engine rich enough not to overheat, but with this little engine we only need a basic setting of the main jet for now so the slow speed needle can do its job.

I hope this helps
Ade

So glad to see that this was just a minor adjustment issue ..... once all the adjustments were properly identified and understood.

Congratulations Raphael, and well done Ade!!!!

Hi Raphael, It is great to see your little engine running so well!


Well done and good on you Ade for helping Raphael get it dialed in.