Dear Sirs:

The engine was running fine on the ground

I made a new balsa box 50 x 25 x15 mm, 2.5mm thickness without holes and put it inside de fuselage some centimeters behind the firewall. I also moved the vent tube output to a closer position to the tank. Now it is 5 -6 cm far from the tank.

Then, I started the engine. 7.000 rpm with Mezjik 23x10. I tried to get some more rpm so I close 10 min the H needle, but this made the engine too lean, and max rpm couldn't be reached again. Stop and re-open 10 min. Start again and ... still lean. Open 10 min... and still lean. And so. Everything seemed to be messed then. The high speed was open about 2 and 1/2 and L also a couple of turns.

I thought something must be dirty, so I dismounted the carb and cleaned it carefully, but I didn' feel brave enough to disassembly too much. On one side, there is a small thing moved by a spring. This part was alrady completely clean so I didn't anything there. In the opposite side, where there is a small hole with a filter in, there was a bit of dirty, not very much, not solid things, only something like small bubbles or foam. I cleaned it carefully with normal fliying mix and reassembly. I also took apart both needles, being very careful don't exchange them. Cleaned both, reinstalled and moved as per book position: H 1h 10min. L 1h 45min.

Started the engine. H was far lean.
Disconnected the reference pressure tube from the balsa box, but remain the tube inside the fuselage.
Open and open. Now it works on the ground nice, but the H is open 2 and 1/2 turns, and L is about 2 turns. With this setting working fine, I connected the reference pressure line to the balsa box and L and H became lean again.

Now it is disconnected and working on the ground, but with all this tangle I hadn't time to check it on the air. I'm confused about how this carbs work. I really don't understand them. I'll check the model in the air next weekend.

Thank you for your help
Regards,
Javier