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HelicopterMain Discussion › OS 105 HZ R Bogging Down when Pressurized
03-07-2016 08:28 AM  19 months agoPost 1
mrblonde0083

rrNovice

Redlands, CA.

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I have an Align TREX 700N DFC heli with an OS 105 HZR engine. I'm still breaking in the engine and I have all the pins at factory settings. I'm also currently running Cool Power 15% fuel. I've run into a couple problems that I would like input on.

I have noticed that my head speed, even at fully open throttle, was only around 1800 rpm. I'm certain that this engine is capable of more power and perhaps its just because it's not fully tuned yet. Also, when spooling up, just below mid stick, the engine starts to bog down and sometimes dies. Now again, this might be because the needles still need to be tuned. However, today I forgot to close the in-line valve that pressurizes the tank from the engine. I noticed that without pressurization, the engine ran a lot smoother, didn't bog down at all throughout the entire throttle range, and had ALOT more power and head speed.

I understand the benefits of a pressurized system and given that I already have the engine, I would like to get it to work properly.

So here are my questions:
1. I've noticed on the forums that a lot of people are running the needles very lean. Is this so they can get the head speed up due to the pressurization? Are there any suggestions on how to correct this problem or is it just a matter of tuning?

2. Is anyone else having the same problem with pressurizing the tank? Is this normal?

3. How do I address the issue of it bogging down just below mid stick when spooling up?

4. This is a little off-topic, but I'm considering changing over to Cool Power 30% fuel and in the manual, it states that I need to install the other two shims for easier tuning. Is this really necessary or can I get by with the .2 shim that is in there now? I've read on the forums that a lot of people are having problems tuning without installing the other shims so I probably will install them once I switch over. I just want to get some input to know whether it is required or not.

Any helpful suggestions would be appreciated.

Thanks in advance.

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03-07-2016 11:02 AM  19 months agoPost 2
Ladymagic

rrKey Veteran

South Korea

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There are several issues that could be at play here. I would start simple first. I would start by checking that your glow plug is not fouled. Also, check your heat sink is tightened down properly.

For the pressurization, please verify that your one-way check valve is not installed backwards.

I am running an .91HZ-R and I also used to run an .91SZ-R with the same problem. If your engine running fine at idle, but gurgles when transitioning to mid and high please check that your mid range needle valve is in fact set to default. You are likely too rich on your mid range. Dial it in a few notches progressively until your engine will transition smoothly from low to mid to high and back down again. You might have to disable your gov for proper tuning.

Good luck.

Mellisa

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03-07-2016 01:01 PM  19 months agoPost 3
Dr.Ben

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Richmond, VA, USA

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Tell me where you have the needles set. It sounds like the needles are just set too rich, even for a new engine. Please do switch to a low viscosity oil fuel because that carb system is challenged dealing with a thick(er) oil package as is found in CP15. To be clear, the nitro content is fine; thin oil is preferred.

Ben Minor

Team Synergy Team Futaba Team Kontronik USA
Progressive RC

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03-07-2016 02:42 PM  19 months agoPost 4
don s

rrElite Veteran

Chesapeake, VA

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Barring any other issues, I've found that my stock 1.05 HZ-R is happiest running 30% rotor rage. Better performance, easier tuning.

E820, Raptor G4N, X50F/E, E620, Forza 450, and some planks.

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03-07-2016 03:33 PM  19 months agoPost 5
Flyin for Jesus

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Dana Point, Ca. 92629

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Sounds like you're way too rich. Since less fuel pressure means less fuel to the carb and it runs better, time to lean it out a bit.

Can't comment on fuels and oil viscosity.

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03-07-2016 09:26 PM  19 months agoPost 6
mrblonde0083

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Redlands, CA.

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Thank you everyone for the input. The needles are currently set at factory defaults, which the book says is on the richer side. However, I've noticed that many people posting on the forums are running the needles VERY lean, which may be due to the pressurized system.

Factory defaults for the high is 2.5 turns open from close, and mid is 1 turn open from closed. Oh, and I did check (several times) to make sure the one-way valve is installed in the correct orientation.

I still have a question about the additional shims for the engine. I still have 2 gallons of the Cool Power 15% fuel that I want to run through the engine to finish breaking it in. I know I will have to retune once I start using the 30% fuel. If I take the engine out, and install the other 2 shims as recommended by the manual for use with 30% fuel, will I still be able to run the 15% fuel in the meantime until I get the 30%?

Thanks,
Larry

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03-07-2016 10:38 PM  19 months agoPost 7
JayL

rrVeteran

Leesburg GA

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I tried to run 15% CP when i first got my 105 and did not like it at all so went to 20% and have not had a minutes trouble. on another note you really cant go with what other folks needles are set at as each engine may be a little different just set the needles until your happy with the results.

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03-07-2016 10:41 PM  19 months agoPost 8
mrblonde0083

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Redlands, CA.

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Thanks, JayL. Did you install the other shims on the engine when you switched to 20% CP?

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03-07-2016 11:46 PM  19 months agoPost 9
Glenn Goodlett

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California

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I run both of my 1.05's on 30% Rotor Rage with only the single stock head gasket. Have been running it this way for years. It is harder to tune but makes the best power in my opinion.

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03-08-2016 01:25 PM  19 months agoPost 10
dkshema

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Cedar Rapids, IA

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Don't over analyze. Is this your first-ever nitro engine?

Break it in, gradually lean out the high speed needle. From a hover, apply full throttle and climb vertically as long as you can and listen to the motor.

You want to get to the point where the motor continues to pull well, without beginning to sag. If you get to that point, you have gone too lean. Open the high speed needle a few clicks so you are just slightly rich.

Adjust the low speed cam to achieve a smooth transition from idle to full speed. If, after sitting at idle for 15-30 seconds, the engine spits and sputters as you suddenly go to full throttle, the idle is too rich. If the engine hesitates, or just plain stops, the idle is too lean.

After you get a decent setting for idle and full speed, go back to the full throttle punch out. Climb vertically for a few seconds, then go to zero collective while watching the exhaust. A large amount of smoke says the mid-range needle is too rich. No smoke says it is too lean.

Forget about other people's settings. They don't live where you do and they are running different fuel and maybe muffler.

Fuel with a lower nitro content requires that the needles be a few clicks leaner than a higher nitro content fuel. If you get the needles right for the fuel you currently use, you will need to readjust and open the needles as you go to 30% fuel.

When setting needles, always err on the rich-side.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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03-08-2016 03:22 PM  19 months agoPost 11
mrblonde0083

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Redlands, CA.

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Is this your first-ever nitro engine?
Thanks, Dave, for your input. This isn't my first nitro engine (I have several nitro planes), but it is my first heli nitro engine and the first with a regulator and pressurized system.

To be clear, I'm not trying to duplicate other people's needle settings. I know I need to set the needles for my own heli and that it will be different than others. I just noticed that a lot of people seem to be running their needles very lean and I was curious if this was due to the system being pressurized. I've never dealt with a pressurized system before and I thought it was odd that the engine ran better when not pressurized. One person posted that the pressurized system is forcing fuel into the carb and may be running it very rich as a result. That makes sense to me and explains why others would be running the needles so lean.

Since this is my first nitro heli engine, I'm learning a lot about the mid-range needles which is new to me. Everyone seems to be saying to lean out the needles to fix the problems I'm having when the system is pressurized. I'll work on that this weekend when I take her out and see if that solves the problems.

Thanks everyone for the input.

Larry

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03-08-2016 07:35 PM  19 months agoPost 12
flyfish

rrApprentice

New Jersey

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this may help?

Watch at YouTube

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03-09-2016 02:52 AM  19 months agoPost 13
dkshema

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Cedar Rapids, IA

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If you ever used muffler pressure on your planks, taking the pressure fitting on the muffler, and connecting it to the vent line on your tank, you HAVE been using a pressurized system.

YS was a pioneer in the application of a demand regulator to a model aircraft engine. For awhile, James O'neal at OMI industries would adapt certain OS carburetors to use what was a commercially available demand regulator to make certain OS 91's run reliably. OS was a bit late to the game, playing with the Perry micro oscillating pump, an OS design pump, and eventually landing on their own design carb using an OS design demand regulator (which, curiously, inside looks like the Cline).

So, back to your muffler pressure setup. This is a pressurized system, however the pressure in the tank is not consistent; it varies with engine RPM. It has several drawbacks, however. One, whatever is in your engine's exhaust finds its way back inside the tank. Unburnt fuel, lube, and gases which can lead to corrosion of the guts of your engine, and which cause the fuel pickup line inside the tank to rot, split, and fall off at the most inopportune times. The level of fuel in the tank affects how well this pressure system works, so you don't get consistent motor runs from full tank down to empty. A downside to a non-pressurized system and the system using tank pressure is that if the level of fuel in the tank is higher than the carb spraybar, fuel will readily siphon out of the tank, through the carb, and if the piston is in the right position, into your crankcase and cylinder, leading to a hydraulic lock when you try to start it. If the muffler comes loose/falls off, you get a hole in the vent line, or the back end of the muffler falls off, you instantly go lean and die.

The demand regulator in your OS, in YS, and the Cline regulator uses a pressurized fuel system. However, it doesn't "force" fuel into the carb any more than a tank pressurized by muffler pressure does, or for that matter, any more than a non-pressurized system.

All three of these fuel delivery systems are naturally aspirated, there is no fuel injection going on.

-----

In the non-pressurized system, the up-stroke of the piston in the crankcase creates a lower pressure inside the crankcase than that found outside the crankcase. The pressure differential causes air to enter through the carburetor venturi, which as it is a venturi, has a portion whose cross section is smaller than that of the inlet. As the air passes through this necked-down area, it speeds up, causing the local pressure in the necked-down portion to be lower than that in the tank. Atmospheric pressure acting on the tank (another pressure differential) causes fuel to enter the spraybar, where it gets ingested into the intake port of the engine.

In the system using muffler pressure, the pressure inside the tank is above that of ambient, but variable. The stuff going on inside the venturi and spraybar remains unchanged. The low pressure area in the venturi causes fuel to enter the spraybar and the crankcase.

-----

In the "pressurized" system of the OS, YS, and Cline world, a one-way check valve is added to the system, usually through a nipple mounted on the backplate. On the up-stroke of the piston, that same lower pressure area in the crankcase underneath the piston does nothing to pressurize the tank, but does draw fuel into the crankcase through the venturi and spraybar. The one-way check valve is closed.

On the down stroke of the piston, as the intake port is closed off and the exhaust port is open, the higher pressure inside the lower end of the crankcase causes the one-way check valve to open. As the check valve output side is connected to the fuel tank vent line, the higher pressure eventually builds up inside the tank and reaches a fairly constant value, much higher than ambient.

The outlet of the tank is connected to the inlet of a demand regulator. The demand regulator has a small needle valve inside, a spring, and a diaphragm. One side of the diaphragm is vented to ambient, the other side is on the venturi, low pressure side of the carb. The spring is designed to adjust the point (pressure differential between high-pressure inlet and the low pressure area of the carb) at which the small needle valve inside the regulator opens to allow fuel to flow.

As the fuel tank is under a relatively high and constant pressure, the inlet side of the regulator always sees fuel under a constant pressure. As the low pressure side on the venturi side of the carb demands another shot of fuel from the regulator, it gets it, and it's delivered at a relatively constant pressure. The diaphragm is mechanically connected to the small needle valve in the regulator, opening and closing it as needed (on demand) to allow fuel into the carb.

This allows consistent engine runs from full to empty tank, and no matter what orientation the tank has with respect to the spraybar. Needle setting becomes more reliable and less critical, and not near as dependent upon ambient conditions from day to day.

It eliminates the recycling of burnt exhaust products, allowing the engine innards and tank innards to last much longer, like a Tootsie Roll. If the regulator is working correctly, the fuel will not siphon out of the tank while the heli is just sitting idle on the ground.

What can fail? The check-valve, the diaphragm in the regulator, the needle in the regulator can leak, and you can still get holes in the line between the check valve and tank. Or you can forget to close the system. The result is lean running, erratic running, or no running of the engine. Of course, if you forget to vent the built-up pressure in the tank before opening the fill valve, you get a Nitro shower.

-----

Your rich engine ran better without the pressure as it naturally was running somewhat leaner. You may have gotten lucky as the motor was initially too rich.

The openings ("jets" ) in the carb needle seats may be larger in the demand regulator system than in the conventional system, allowing what seems to be a much leaner setting on the carb than you're used to.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

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03-09-2016 06:34 AM  19 months agoPost 14
mrblonde0083

rrNovice

Redlands, CA.

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Thank you, Dave, for the very detailed explanation. I'm always learning in this hobby. What you said makes a lot of sense. When I take her out this weekend to fly, I'll work on leaning out the needles and see if it fixes my problems. I'll post a reply to tell you what happens.

Thank you all so much for your help with this.

Larry

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03-09-2016 01:13 PM  19 months agoPost 15
dbcaster

rrApprentice

Petaluma, Ca

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You should also make sure that you have the correct main needle seat. Some of the 105's came with a larger needle seat. Pull the seat off and remove the needle. If a 1.5mm allen fits through the seat it is the wrong one. The engine will run excessively rich and be very difficult to tune. You will need to get a smaller seat from OS.

Some arguments are sound and nothing more

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03-09-2016 06:26 PM  19 months agoPost 16
don s

rrElite Veteran

Chesapeake, VA

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make sure that you have the correct main needle seat
I wouldn't say "correct", but different. I've used both, and went back to the "larger" of the two...

E820, Raptor G4N, X50F/E, E620, Forza 450, and some planks.

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