Getting lost with OS105HZR Tuning (first N heli)

[Crumpet]

Bit of a long explanation but thought it was necessary...

So I bought a used 700N with a ran in OS105HZR
I have a lot of nitro plane and car (I race 8th scale) nitro but nothing Heli so mid needles are all new.
I searched the forums and started with the rich side of what I could see people using, 1.5 high end, 1 mid

After a few flights I did all the things I'd seen in tuning guides.
Full pitch climb outs and full throttle loops and the engine sounded good and after a few I landed and the backplate was cool so I repeated, leaning the high needle until it was okay to touch for 7+ seconds no problem (My understanding is these manouvers the high needle)
However, at the end of the climb out I went quickly straight to 0pitch and there was very little smoke.
I then did about 30/40 seconds of tic tocs, checked the backplate and it was really hot. Like, 1second and a burnt finger.
My understanding is tic tocs is mid needle stuff, so I went out quarter of a turn out on the mid as it was so hot.
Repeated the tic tocs and it was still hot but 4 seconds touchable.
I went out ANOTHER quarter turn and after the tic tocs it was 7ish seconds touchable

So the question is, I am now at 1 turn high 1.5 turns mid. Compared to what Ive read the mid needle is a long way out.
I know each engine is slightly different and tuning from temps is rough but am I going in the wrong direction?

Thanks a lot for whoever is brave enough to read all this lol

Martyn

edit: its on 20% opti SLV

[PHewson]

Personally, I prefer more smoke, I run 25% Optifuel.
My 105 on my 700N DFC was setup by Dave Fisher and smokes nicely, more cleaning but have not had an engine blow.
600N and 700N smoke nicely too, again no problems.
In the New Year i do not mind counting the clicks on my mid and high needles if that helps.

[Tim Procter]

My 105HZ-R runs great with plenty of power.

High = 2 full turns out
Mid = 2 full turns out

These engines run great running rich without risking getting hot and burning it up.

[Crumpet]

Sorry I forgot to say I use the 20% opti SLV stuff!

[coolice]

Hey buddy.

Typically OS engines, or any engine running high nitro content fuel, prefer a richer needle setting. The bigger bang produces more heat as we know, so the addition fuel flowing through the engine helps cooling.

With tuning, I always say it's not easy advising via proxy almost, as there is nothing better than hearing and seeing the engine in flight to determine its tune state. But, we can help guide you easily.

The usual logic is to leave the mid range needle closed until the idle and high needle is set, so I'd suggest closing it off for now.
Set the idle to achieve a reliable idle, but still on the richer side for now, as we can always lean it out a bit, but can't take back a lean run.
Then set the main needle about 1.75 - 2 full turns out and go fly.
Hover for now for a few minutes and land to feel the back plate, it should be cool and you can keep your finger on it.
You may find the engine sounding a little laboured almost now, as it is possibly a bit too rich. But better this way than too lean to start with.

If the back plate is cool, now I would start bringing the high needle back a bit to lean the engine out and start doing a few climb outs.
I'd suggest doing these backwards at 45 degrees into wind, so if the engine does stop you can just auto in safely on a 45 degree approach.
Land and check the temps again.

While I'm doing this, I'll also be looking at the smoke trail, which can be a good indication of tune also and you're looking for a nice steady flow with no gaps.
Having said this some fuels smoke more than others, so bear that in mind to.

While doing this I am usually in normal mode, so I can quickly put the engine to idle and enter an auto to observe the smoke and engines behaviour with fast throttle changes. A lean idle needle will show with the engine hanging on the pipe and not dropping to idle. Conversely an engine hesitant to throttle back up in the flare points to a too rich idle setting.

Keep in kind that with the high end needle going leaner you may find the idle will need a slight tweak to compensate, so keep an eye on that to.

With the idle and high needles set, now you'll find the mid range will be lean in most cases, as while hovering the engine may be popping/rattling and so now you open the mid range to compensate at this point in the carbs fuelling.
Open to one turn and try hovering again, you should hear it's got better.

At all times I keep a check in the back plate temperature, as like you've said, you should be able to keep your finger on it for a long time.

In tic tics I think you'll find the high and idle is important here, high for the initial pitch pump up, but then low as you back off and the governor closes the carb as the demand in the rotor disk is removed.
But still you are transitioning through the mid range also, so all needles have a bearing overall.

But in closing, start with the idle and high needle first get then right and then work on the mid range to smooth out the hovering point.

Ian Contessa

[hedge]

Sounds to me like you’ve done everything spot on. Cars are way harder to tune (way way harder) so try not to over complicate it. OS heli engines are very wide on the tuning window and the 105hz is powerful so no need to push it. Engines are engines and the same rules apply to them all. Heat can kill - you’ve got that sorted. Noise, tough one to instantly know but racing cars you’ll know what lean and rich sound like, easiest thing to do is richen the 105 so you get your ear in on a four stroke, then lean as youve done and you’ll find the sweet tuned sound. A 105 is a very deep sound compared to 0.12/0.15/0.21/0.25s so a lean sound on a 105 may well sound rich to you at first. Smoke, as Ian says this differs from fuel to fuel but I personally findthe Opti stufff very smoky so lack of smoke should be a worry :-). Another sense check is flight time, on a normal non dfc 700n if your just flying around at about 1800 hs with no continuous smack - then you should be around 7-9 mins massively less or more start to investigate. Lastly and again this only comes with a bit of experience is the pulling power, a 105 is powerful but not as powerful as a 700 electric with mid to high end gear. That said it’s still very powerful so if your struggling to do a move or your bogging in tic tocs (and your sure it’s not your technique) then richen - always richen first, then lean if your sure it’s needed.

but hey sound s like you’ve nailed it don’t worry about needles.

[waveydavey]

What Hedge and Ian said

[Crumpet]

Hiya guys,

So today I finally got to fly and basically did what Mr Coolice suggested step by step.

I ended up somewhere much more in line with what everyone else has.

Instead of 1 high, 1.5 mid I got 1.25high 1 mid.

Its actually running cooler and much more errrr 'snappy' on fast direction changes like tic tocs.

It was 4deg outside today and no matter what I did I could get over 7 secs on the backplate.

Thanks very much for the help!

[coolice]

Hiya guys,

So today I finally got to fly and basically did what Mr Coolice suggested step by step.

I ended up somewhere much more in line with what everyone else has.

Instead of 1 high, 1.5 mid I got 1.25high 1 mid.

Its actually running cooler and much more errrr 'snappy' on fast direction changes like tic tocs.

It was 4deg outside today and no matter what I did I could get over 7 secs on the backplate.

Thanks very much for the help!

Great news and well done.
You're most welcome and happy flying

Ian Contessa

[Crumpet]

Sorry for the mini resurrection here but today was 8degrees warmer and the 105hzr was running rich and cold. With the cars Id only ever change the high end needle from day to day, but if theres a mid, should this get some attention aswell?

Thanks!

[coolice]

Sorry for the mini resurrection here but today was 8degrees warmer and the 105hzr was running rich and cold. With the cars Id only ever change the high end needle from day to day, but if theres a mid, should this get some attention aswell?

Thanks!

Hey Buddy.

Depends on where you are in the carbs range of travel really, but the mid range needle usually doesn't need changing much if at all once set, so stick with the high needle for now.
You may find leaning out the high needle means you need to richen the mid range to account for the lose in fuel at the hover point. But I can only see you going 2 or 3 clicks on the high needle, so there won't be much change.

Ian Contessa

[Rachel]

from one of the best in the business, hope this helps ! https://www.youtube.com/watch?v=VzNxpbQEV_

[Crumpet]

from one of the best in the business, hope this helps ! https://www.youtube.com/watch?v=VzNxpbQEV_

Hi Rachel, the link didnt work. Would be good to watch it!

Thanks

[bigpops]

An 's' was missing from the end of the link Rachel posted.

Here's the video

[waveydavey]

If you do a full throttle climb out, let it clear it's throat and get onto the top needle, if you stop abruptly do you get a big cloud of smoke? If you do and you're more or less happy with the top end then lean the mid a click at a time until you see no real difference in the transition between top, to mid. I'm sure Dave covers it in his video but tune the top needle first and then back to the mid and vice versa, once in the zone for the fuel and pipe combination they need very little messing with and a click here or there on the top is often all that's needed. When was the last time the bearings were done?