OS 105 HZ R needles

[jeffsg61]

Originally Posted by CyprusFlyer

Well that does not initially make sense in my mind but you may be on to something. Just tuning in a new 55HZ-R yesterday and already down to 1.25 High 0.5 mid and thought oh no here we go again!
Just checked my tube and 9 cm for some reason, extended to 13 and will try again tomorrow. It could be that the piston needs to travel further pushing a longer column of air before the valve opens, then it shuts off at the end of the down stroke, less air being pushed out, now that makes sense. Just another b**** variable in the system, hopefully its not that critical after a certain point and the regulator does what it should.
Kudos for experimenting with that variable

Just make sure that when extending that line there is still enough pressure in the tank.. I usually run the motor for a few seconds on the ground, shut it down and check for pressure. I wish there was a spec for the proper pressure.

[CyprusFlyer]

Originally Posted by jeffsg61

Just make sure that when extending that line there is still enough pressure in the tank.. I usually run the motor for a few seconds on the ground, shut it down and check for pressure. I wish there was a spec for the proper pressure.

Good thinking, will look for that, will start longer at 13cm and cut 1 cm at a time if pressure is too low, be good to rig up a pressure meter and see, now theres a thought, I have some aircon stuff, maybe too high for resolution but will think that over, probably need 2/3 bar measurement.

[Steve Graham]

Don't know how long the line is on my 105. I've been running it and a 91 HZ-r before that for several years and I always have a great deal of pressure in my tank, the tank is swollen. Never had it throw a line from the pressure. I think the pressure on the inside of the line actually causes the line to grip the barbs on the fittings? I generally see my high needle between 5/8ths and 3/4s open from full closed and the mid just over 1/2 out.

[kleinum]

Hi all. I have followed this thred a bit since I bought a used 700N with a OS .91 HZ-R engine. From what I have seen so far (and I'm now starting to get in the ballpark at needle settings) is that the stock needle settings on OS engines is ONLY valid when using 30% nitro. Anything lower and you will need to run a MUCH leaner setting.

My engine did not even run with stock settings, and I had to lean the mid a lot just to make it hover before I could start tuning high end. I also need to lean the idle a bit to make it run nice without doing the obvious fault of just cranking up the trim

And it does not help at all that all OS manuals have a typo in the first part describing stock neede settings. "Two halv turn out" should have been "Two AND halv turn out". This is repeated correct at some later chapters, but who reads all pages before firing it up for breaking it in !!

I think the .91 produces great power for my flying with 15% nitro, and another benefit from running a lot leaner settings is the flight time At 1950rpm HS I run a full 10 min flight. (Mild 3D)

All of these settings have been done in conditions with 4-10 degrees outside temperature, and when the summers hits it will be needed to run even a bit leaner...

(I have now bought a second hand OS .105 with only 1 tank on idle running thru it, so I can also get back with my 15% needle setting when this is tuned during the season...)

[CyprusFlyer]

Good information, thanks, currently tuning an OS55 HZ-R, similar problems, but almost useable after I wound the mid needle in to just less than half a turn. 5 Litres through it so far and running 15% which is too low for the engine but OK for gentle run in.
I am now switching to 22.5% nitro and will retune from scratch, will be interesting to see if the settings approach the OS manual recommended. I would never thought that the settings would change by such a margin, if so OS should be publishing a table of needle position versus nitro content!
I did try the fuel tube length adjustment to the check valve, 13cm gave me a strange slow variation in engine speed, almost cyclic at about 2 secs, so definitely changing the pressure characteristics.

[CyprusFlyer]

Well back to square on, I cannot see I have two crazy engines!!
Tried the OS 55HZ-R on 22% nitro, tried to find lean and down to Main fully closed and Mid 5 clicks open from closed, still rich and temp less than 70 deg Centigrade. To say I am getting p**** off with these is an under statement.

[Rodney Kirstine]

On my 105 I found that the idle and mid-range needles really affected the high speed needle adjustments. I was finally able to get my 105 to run a bit lean. I started my tuning over, from scratch, and began with the idle mixture. It was rich, to start. Next, I did some adjusting on the mid-range needle because when I would go from normal to IU1, it was really stumbling because it was so rich. I leaned out the mid-range needle to the point where it was spooling up pretty smoothly and then I began working on the high speed. After that, it was a combination of going back and forth between the mid and high-speed needles.

[CyprusFlyer]

Originally Posted by RodneyK

On my 105 I found that the idle and mid-range needles really affected the high speed needle adjustments. I was finally able to get my 105 to run a bit lean. I started my tuning over, from scratch, and began with the idle mixture. It was rich, to start. Next, I did some adjusting on the mid-range needle because when I would go from normal to IU1, it was really stumbling because it was so rich. I leaned out the mid-range needle to the point where it was spooling up pretty smoothly and then I began working on the high speed. After that, it was a combination of going back and forth between the mid and high-speed needles.

Thnaks maybe I ought to do the same on the 55, have not touched the idle because it is reliable, must say it does stutter on spooling up from idle, maybe try the same thanks.

[Rodney Kirstine]

Mine was idling pretty good, as well, but after I did the pinch test on the fuel line I found that it was actually still rich.

[CyprusFlyer]

Know what, hopefully this is a case of RTFM
Tuning chart says:
" Warm up the engine.
Observe the mixture condition while floating the model
lean mixture? IDLE mixture screw CC ......Rich mixture ? IDLE screw clockwise 5 deg blah blah...
"
Now thats a subtle instruction, especially when the idle is just fine and most peaple say "dont mess with the idle, factory setting is usually just fine".

So starts with the idle screw which is actually the mixture control valve, turning it shifts the whole mixture adjustment curve up and down now I come to think of it and will shift the curve into the ballpark area.
B**** H*** I think there might be a eureka moment coming up thanks.

[Sirolf]

Okay then... keep us posted!

[Rodney Kirstine]

Exactly. I remembered that in that video that Finless Bob and Tim Jones did, Tim mentioned the interaction between needles and that changes in the mid-range would shift the high-speed. I decided to read through some more tuning posts and that's when I noticed that item number one was to adjust the idle mixture.

I had really meant to post about this last week when I finally got mine running good but part of me was really worried that I wasn't really seeing what I thought I was since I still don't have a ton of nitro experience.

[CyprusFlyer]

I have watched them about 10 times, nothing really about these regulated engines from OS. I have a YS91 Tareq that is regulated but it was easy to tune, the fuel flow to the needles is independant of each other, I think of them as in parallel.
The OS on the other hand is in series with the high feeding the mid.
The idle on OS adjusts a brass valve that has a V channel used by the throttle barrel venturi to adjust the fuel flow according to the throttle position. Its this V channel that is shifted to calibrate to available pressure then.

[Rodney Kirstine]

So, I definitely verified that I can tune mine to the point where it is running lean. I started it up, hovered for about a minute in IU and then landed and hit throttle hold. It did not want to return to idle, at all. I feel like I'm finally starting to get a bit of a handle on this. Of course, now that I've said that, I'll grenade my motor, LOL.

[CyprusFlyer]

Ok sorry no eureka moment after a week of experimentation and a few gallons of fuel on my Synergy N5C with OS55 HZ-R 22% nitro, Hatori pipe.
Experimented with the idle screw and all I got was the annoying ring a ding nonsense on hold indicating too lean. Managed to get reasonable power but main was at half a turn and mid at quarter turn out, ridiculous!
Not only that had 2 regulators stick open on me yesterday and today with a flame out in flight, auto was ok but regulators sticking open, in one case a big puddle of fuel over the flight line.
Thats with a fuel filter inline, two in the fuel can and it also did it with a new inline filter after flushing out the pipe with clean fuel and 2 seperate regulators.
Exact same thing with my 105 HZ-R that is now in storage after fitting the YS91.
So thats it, all the -R crap is coming off, I have a OS91 HZ needle that closes fully so plugging up the crankcase cover and sticking a nipple on the Hatori for tank pressure, might enjoy flying it then!

[CyprusFlyer]

OK, OS 55HZ-R, put a clamp on the crank case pipe, removed the regulator and main needle seat, fitted the fuel inlet ring and a 91HZ needle seat, actually same part number as 55HZ, fitted the Hatori pressure nipple and adjusted the plumbing.
Took about 5 mins to find reasonable needle settings the another 15 min to get a basic tune.
Wow, different engine, loads more power, no more fuel pissing all over the place, no more spitting when opening up the fuel lines to refuel.
Just had 4 fun flights this afternoon, still a bit rich but needle settings were Main 1.3 ish and Mid just less than 1 turn out and idle back to the middle.
Will go for fine tuning when I have more open space and less wind but not going back to that regulator nonsense, never buy an OS fitted with one.

[Sirolf]

[dchekas]

Very puzzling.

My 1.05HZ-R is just under 3/4 of a turn out on the main needle, running Rotor Rage 22.5%, and it's running like a beast.

Idle is at stock setting, mid needle a little under 1 turn out.

There's 3 other OS 1.05HZ-R's in my area, all with Hatori SB-22FH, running Rotor Rage 22.5%. All our needles are in the same ball park.

Another guy here has a OS55HZ-R in his 600N DFC. We're at 1.4 turns out on his high needle, and his is starting to come into the power band. Running rotor rage 30%.

At all the events I've been to the last 3 years, and all the engines I've helped tuned, I've never seen an OS engine behave like this. Very strange to say the least. Wish you were in the states, as I'd love to take a look at it in person.

[dodgeboy]

My OS105HZR needles are about the same as yours. Im running 23% VP and it has good power. It doesnt touch my YS91srx but it does the job. The ys 91srx i have in my N7 makes the 105 seem like I have my nx4 os37 motor in my TSA 700.

[datatools]

Has anyone made progress with the 105HZ needle setting? Mine is fully closed and still running rich.