OS 105 HZ R needles

[Lazybfarm]

Does anybody know if the mid and main needles on the OS 105 HZ R are the same , or different? I'm having trouble startin mine and upon checking the needles I find that they are the same, is this right?

[tcappert]

They are both the same...needle assembly O.S. part #29085910
http://downloads.hobbico.com/evpl/osm/ev18750.pdf

[dchekas]

More details.

Is this a new engine? Was it running well previously? What are the needles set at?

What makes you think the needles are the source of your starting issues?

[Lazybfarm]

No fuel getting to the carb, I have good pressure in the line going in to the reg. This is a brand new motor, never started. Maybe some trash in the reg. I was just trying to diagnose the trouble and realised that both needles are the same , didnt know if that was right. Thanks for the reply guys.

[borgo]

so Lazybfarm

what was it? because i've the same thing, when i blow into the regulator its looks like its closed at all. but i no there must be vacuum in the system to pull the sheet in the regulator down and then there is going fuel into the carb.

but i found a thread here on hf that the high needle isn't well from the factory,he do not closed at al??!!!

that means the motor is too rich, i writh this because i have a hard time too start my engine and had a few hydro-locks too.....maybe you found the problem?

[CyprusFlyer]

Mine starts easy but have the problem running rich even with main needle fully closed.
Beware there is a miss translation on stock needle settings in the manual, should read:

Main 2 half turns = 1 Turn
Mid 1 half turn = half a turn.

Mine stopped the hydro locking nonsense when I found this and started easily with a Sullivan on 3S battery!

See my thread on checking the regulator, its easy and easy to strip and clean too, just don't let the tiny parts escape on the floor!
Also I just gave the diaphram a wipe with tissue but used acetone to degrease and clean the metal parts.
After a flight mine holds tank pressure for at least 30 mins, good sign that regulator is OK, other wise if it doesnt shut off then flooding will occur.

Just waiting for a 91 HZ needle valve holder to try and lean the damn thing out.

[Gscott]

I'm curious what length of fuel tubing people are using between the back plate and one way valve. It's possible that there is too much pressure which may force excess fuel through the regulator. It may have been with a YS but I seem to recall a shorter distance equated to higher pressure so it may be worth experimenting with a longer piece of tubing between the crank case and one way.

[borgo]

Mmmmm yes maybe is that the solution.i have the check valve 2cm from the crankcase

Maybe i have remove him a little bit, and yes i've read your tread for checking the regulator.thx for that.

Anyone no how i can check that my high needle is ok?

[rctintin]

Interesting read as I have a brand new un-run 105HZ-R in my new Synergy N7. The weather is shocking here in the UK with high winds and constant rain, so no time soon to maiden her.

Re the one way valve, it says to put the check mark towards the tank, but if you blow down it, its sealed that way!! Which way should it be?

Cheers,

[dchekas]

With the OS regulated engines, the pressure is generated by the down stroke of the piston.

When the piston travels back up, it will pull a vacuum on the backplate.

The check valve is there to allow the pressure through from the down stroke of the piston to your fuel tank, but prevent the pressure from being sucked back into the engine by the upstroke on the engine.

So, if you pretend your mouth is the engine, if you blow through the tubing to the valve it should open. If you inhale or suck the tubing, it should seal.

[CyprusFlyer]

Originally Posted by rctintin

Interesting read as I have a brand new un-run 105HZ-R in my new Synergy N7. The weather is shocking here in the UK with high winds and constant rain, so no time soon to maiden her.

Re the one way valve, it says to put the check mark towards the tank, but if you blow down it, its sealed that way!! Which way should it be?

Cheers,

Rob that is correct, you should be able to open the valve by blowing hard down the pipe, I tested mine with a syringe to pressure test the tank as Chris suggested too.
Another thought about extreme rich running is the length of pipe from crankcase to check valve, 10cm in the manual. I cannot for the life of me reason that a shorter pips would increase the tank pressure as its the same volume of air that gets pushed through!
Going to check mine but different needle valve holders on the way, get this working one way or another!
Just a thought, if you really want to test, just close off the tank fillers etc and run the starter for a few secs, there is plenty of oil from factory to lubricate the engine, the air should hiss out when the filler is released.

[borgo]

mmm alricht....i'm waiting for a new startershaft now. i had a hydrolock and now the startershaft is a little banana

so when the parts are here im getting everthing on place again and set the checkvalve a little bit futher to the tank.....i think i will try 6-7 cm from the crankcase....and than i will test the high needle for correct working.......keep this tread alive.....

[CyprusFlyer]

I am waiting now for a new clutch liner for my N7, brain fart destroyed it!
Checked my one way and the tube was 9cm so cut the recommended 10cm length, not holding my breath that this will make the slightest difference!
To be honest I will not be happy until I fit the 91 HZ needle assy and see that it actually goes to fuel cutoff when closed so a week or so until I am in a position to test again.

[dchekas]

I've forwarded this to the man himself, Steve Helms.

The main needle doesn't fully close against the needle seat by design in the regulated engines.

It is necessary for the main needle to be partially open at all times for the diaphragm to operate properly above 1/2 throttle.

If your engine is running very rich at 3/4 open, there's something else going on, and using the 91HZ needle seat is simply masking another issue.

[CyprusFlyer]

OK, seems that changing the needle valve seat is effectively changing the design parameters, however it doesn't answer why there are a number of us poor guys experiencing problems with an expensive brand new engine, I don't mind tinkering in fact enjoy it as long as a good result is in sight.

So spent a few hours today looking further, dropped the engine out, removed the carb and had the manual open on my PC, in almost operating theatre type cleanliness, carefully stripped the carb, all is 100% correct. It is pretty complex with a number of variable fuel inlets/holes/channels, I could observe that the main inlet opens up proportionally with the barrel as expected. So looking for rich, not really blockages or that would be lean and it idles nicely but runs rich with the main needle FULLY CLOSED, (we know that the needle does not fully cut off though).

Therefore there is one logical explanation left (in my opinion), the regulator is a simple demand valve, similar to what is on scuba tanks, ie the diaphragm opens a tiny valve when the pressure on one side is less than ambient pressure on the other. My thinking that it was a digital on/off device is probably wrong. So to run extremely rich, I suspect that the regulator is opening up too much as the fuel is under quite a bit of pressure, it would only need a tiny particle in that valve to mess up the pressure regulation.

So stripped my regulator, nothing conclusive but cleaned thoroughly, nothing sticking and happy that it is functioning with the suck test I described in another thread. Will test again later next week when my clutch lining arrives.

[borgo]

mmm thx for post dchekas...........ok thats allricht my parts are arived today and the bird is ready to run.....ive looking in the regulator as well and found nothing thats let the regulator open for a pretty rich motor.....so far i dont no what is wrong with my motor because of the hydro's..................now im testing it and will post later the results...............


thanks CyprusFlyer for thinking with me........

[borgo]

so guys a little update about my problem....i can say that i have make a mistake about the the vbar software because i run a vbar gov....so i have setting the wrong throttle curves in it,in combi with wrong throttle servo values and that explain the hydro's......and i have a gasket take out from it.because i fly with 20% and i had 2 gasket in there,the 0,1 and the 0,2 so that was to much i think...... yessss i can say that my motor i running very well now.....way to rich because there's comming planty of nitro out of my muffler but thats just a needle thing......so i hope that you guys can find the issue?

[CyprusFlyer]

Ah the VBar setup, also make sure your VBar throttle curve in the governor tab is set to a V curve, just click on the preset, backup if sensor goes and also sets how aggressive governor is.
Put a new clutch liner in my N7 now so may be flying soon. I have the 91HZ main needle, that one does close completely but prefer not to use it yet.
Hopefully rich running was the regulator, logically can only be that now, hopefully the clean and re-assembly of the regulator will sort this engine out.
Best of luck

Alun

[Steve Graham]

I think there is some potentially useful information coming out of this thread. I've been running the OS regulated engines, first a 91 and now a 105 for a couple years. It really doesn't help that OS, who makes a good engine, does such a crap job with the manual and then chooses Hobico for distribution, good luck getting intelligent support from them. Members helping each other out is what the forum is all about. Here's my take on a couple of these issues.

Check valve: I had a bunch of check valves fail and was blaming them. I finally discovered that certain after run oils like Evolution will destroy the diaphragm. It may fail either open or shut when it does. Since going to a non synthetic after run oil I've not had any further issues with check valve failures. The check valve must be installed in the correct orientation. Air should flow through it from the direction of the engine to the tank but not the other way. Check valves are easy to test as previously mentioned. Check them in both directions. I know the book lists a length from the back plate to the tank. No explanation why in the manual. I do think that the length could slightly effect the head pressure in the tank in the following way. When the pressure pulse enters the silicone tubing it expands slightly before the check valve reaches its pop off pressure. With more tube in front of the check valve the volume of air required to fill and expand the tube to the point of pop off would be greater. This would have the effect, IMO, of reducing the volume of air pumped through the valve. Would this have a noticeable effect on the head pressure in the tank? Personally I doubt it unless you had a very long length of tubing before the valve. A normally functioning OS DRS engine will put a LOT of air pressure in the tank which I've seen hold for several hours after shutdown when I forgot to vent it. I do think it's a good idea to vent it fairly soon at the end of the flight.

Needles: Inexcusable for OS to allow the errors in their manual to exist as long as they have without official correction. I'm at 5300 feet MSL so I should be running a little leaner than those at sea level. If it's true that the main needle isn't fully closed when turned all the way in that explains a few of the strange things people have experienced. I've always found my sweet spot tune at a little over half turn out on the low needle and somewhere between 3/4 and one turn out on the high.

Flooding: I personally find that I have a higher than average chance of flooding on the first start of the day if I don't do the following when I'm done flying. Vent the tank, disconnect the fuel line from the engine and start it. Let it run dry. Attempt to start it several times after it quits. It will normally run and sputter a few times. Once it's run dry, open the throttle all the way and crank it for a few seconds. This clears all fuel from the system and ensures you start from a known, lean, condition next time you fly. Clearing the engine in this way is far easier than clearing a flooded engine prior to the first start of the day.

I also recommend storing the heli with the tank full and capped. It helps keep the rubber fuel bung pliable so it doesn't leak.

[dchekas]

Cyprus,

You are correct regarding the regulator. It is not simply an on/off device, it adjusts itself according to the amount of suction generated against the diaphragm. The more vacuum, the more the diaphragm will press the lever, and the more fuel it will allow into the engine.

If there is debris, or the valve seal becomes damaged, the regulator can leak. Similarly, some fuels might gum up the regulator components. All this leads to the regulator allowing more fuel into the engine than desired, causing the engine to run very rich.

I would try and swap regulators with a friend and see if that resolves your issue if this latest cleaning didn't fix it.