OS55HZ Hyper tuning

[MartinH]

Mine is around the same as Paul's, a little leaner on the top. Be careful not to go too lean in the middle, it can result in the engine cutting.

Smacktalk RC and Bert Kammerers engine tuning guide is very good.

I watched that vid, quite good. Could of been a bit longer on tuning rather than an interview at the end . All good though.

[Planehazza]

Just found this thread, very helpful, thanks!

[rockyrotti]

Hi guys, I have just brought a second hand os55hz that has just been rebuilt both needles are 2 turns out and i have put 3 tanks through it , i was going to get some head loaders to tune it would anyone recommend headloaders or not .

[waveydavey]

No just fly it at that, 2 turns out is excessively rich but you'll soon lean it in. My recommendation would be don't lean the mid too much and follow the tuning guide above

[rockyrotti]

Thanks waveydavey , a big help as not had alot of experience with nitro .

[waveydavey]

The 55 is a superb engine, I had cutting issues to start with and a few bills because of it. I found that it was down to running the mid too lean, I'd go for a handful and as I went through mid it would cut.

[jimmyhorns]

3. Medium Speed Needle
The Medium speed needle is for fine-tuning the midrange.
The midrange is used a lot in hovering and also in 3D because in between high load manoeuvres the engine falls back to the mid-range.
• Hover a minute
• Do a full pitch climb to a great height.
• Decend with 80%-100% negative pitch while the helicopter is horizontal.
• Listen to the engine for the “Hanging RPM” effect (as described earlier)
o The engine will go to 40% throttle, (in Idle up) which is the mid-range, but with
no load on the engine.
Just like tuning the Mixture Control screw, the “Hanging RPM” rules apply here.
• Tune the Medium Speed Needle until the “Hanging RPM” effect is gone

This bit doesnt make any sense to me at all. In operation the engine is under load at mid throttle, whereas in this test there is no load on the engine, as the blades are driving themselves.

[waveydavey]

But in a full pitch descent you should be on the main needle, as you stop you will go through and on to the mid with say 50 to 60% throttle. If it hangs then it's too lean.

Myself I tune the top and then into tick tocks either elevator or aileron, you will soon see whether the mid is lean, smoke disappears it's too lean or if the engine starts to bog a bit. If it can't hold headspeed in the tick tocks but you've got loads of smoke then it's too rich. A click or two at a time is all it needs.

edit: just read it again, I think he means that instant where you transition from the high needle to the mid.

[jimmyhorns]

Thanks waveydavey, thats the bit that I didnt get;

idle up 40% throttle never happens on mine, and at 80 to 100% negative pitch it would be on the high needle.

If you are testing going from the high needle to the mid, then arnt you testing the high needle rather than the mid?...