OS55HZ Hyper tuning

[Spanner]

OK, N5 is built and ready to go

I've got the needles at factory settings, idle central, mid and high both 2 turns out.

I've started her just to check she runs, and she is running VERY rich as I expected.

Where do I go from here? I've had nitros before but none that cost so much!
I guess just lean the mid range out by a few clicks at a time and gradually lean the high speed in over 5 or 6 tanks, then tune for power/reliability?

[callum]

For the first 5 or 6 tanks you will want to run the engine quite rich to break the Engine In, Not stonking over the top rich else that will do the breaking in process no good. After the first 5 to 6 tanks then I would start tweaking the needles a bit

[Spanner]

Would you start leaning the midrange needle first? or a combination of both mid and high?

[callum]

Would you start leaning the midrange needle first? or a combination of both mid and high?

This is where a more experianced person with 3 Needle carbs would come in handy..

They all bounce off each other, You would really need to put the engine under some load,

For example.. Entering the mid range of the Engine it's really boggy, Yet when you enter the high range is perfect.. Then I would lean the mid range a bit..

I had a great 3 Needle Carb guide some months a go, Shall see if I can dig it out..

Take a look at this though.

RC Heli Magazine :: Learn How To :: 2-Stroke Tuning

[Spanner]

Cheers Callum

[callum]

Anytime

I would try and get the idle set good, As that might make things easier with the mid range needle.

Shall try and dig out that guide

[callum]

Found it

Here's the link to the PDF: http://www.jupiter-venlo.nl/Algemeen...0EN%20v3.1.pdf

Pasted here:


3 needle engine
The difference with a 2 needle engine is
the extra needle to fine-tune the
midrange.

Tuning order:
1. Mixture Control Screw
2. High Speed/Main Needle
3. Medium Speed Needle


1. Mixture Control Screw
This screw primarily controls the idle setting on the engine.
Idle settings must be set first. There are two way to do this:
1. Pinch test
2. Hanging RPM

Pinch Test
The pinch test is the First method to tune your Idle Setting:
1. Hover the helicopter for 30 (somewhat) seconds
2. Land it and drop the RPM to idle
3. Pinch the fuel line closed just before the carburetor (where the fuel line is connected to
the engine) and start counting the seconds
4. The engine should rev up and die because of lack of fuel.
5. If this is between 3 and 5 seconds its all right
a. Sooner? Too lean
Turn the Mixture control screw richer for 10 degrees counter-clockwise
b. Longer then 5 seconds? Too rich
Turn the Mixture control screw leaner for 10 degrees clockwise
6. Return to step 1 until you got it right

Hanging RPM
If an engine is running lean then the RPM will “hang” (RPM stays high for a sec) is the throttle is
lowered to idle.
1. Hover the helicopter for 30 (somewhat) seconds
2. Land it and drop the throttle to idle
3. The RPM should drop immediately
4. If the RPM do not drop immediately but kinda “hangs” in a higher RPM before dropping
a. Too lean
Turn the Mixture control screw richer for 10 degrees counter-clockwise
b. Return to step 1
5. Does the RPM drop but the engine is smoking heavily and is sluggish?
a. Too rich
b. Turn the Mixture control screw leaner for 10 degrees clockwise
c. Return to step 1
6. When you got it right, turn it rich for 10 degrees and you are done.



2. High Speed/Main Needle
During full load (100% throttle) only the High Speed Needle is effective.

Step 1
Hover the helicopter and check if the RPM stays stable and the smoke is “normal”.
• Is the RPM increasing after a while? Then its too lean.
o Land the helicopter and turn the Main Needle 3 clicks counter-clockwise (richer)
• Is the engine loosing power after a while? Then its too lean.
o Land the helicopter and turn the Main Needle 3 clicks counter-clockwise (richer)
• It the engine sluggish and not getting up to speed? Too rich.
o Land the helicopter and turn the Main Needle 3 clicks clockwise (leaner)

Step 2
Fly the helicopter full speed horizontally.
• If the engine is loosing power it is too lean.
o Land the helicopter and turn the Main Needle 3 clicks counter-clockwise (richer)
• If the engine is running too rich then it is sluggish and will not come up to speed.
o Land the helicopter and turn the Main Needle 3 clicks clockwise (leaner)
• In doubt?
Play around with the Main Needle until you get the optimal performance.
o Another way to fine-tune this is to do a fast forward flight and do a hard climb into a stall-turn.
Listen to the engine bog down. Play with the Main Needle to get your optimal performance on this manoeuvre.


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


Overall check
• Touch the back plate of the engine for temperature check..
o 30 Size: You should be able to touch the back plate for 5 seconds without burning your finger.
o 50 size: for about 10 seconds
o 90 size: Warm, but not hot, You would be able to keep your finger on for ever.
• Too Hot?
o Then it is too lean
Turn the Mid-range Needle more rich. (10
degrees counter-clockwise)
• Very cold?
o Too rich
Likely to be VERY smokey and sluggish
Turn the Mid-range Needle more lean. (10 degrees clockwise)
• It could come from other Needles.

[Mslater]

My OS50 - seems to run fine - but on the pinch test it doesn't speed up and die it just dies after about 3 seconds.

Does this indicate a problem or are 50's just like that ?

[oneandonlyian]

hey guys watch these videos they show you a lot on tuning a 3 needle carb and also big up the new ys120. Easier to watch instructions than to read em if you ask me.

http://video.helifreak.com/?subpath=...ngp2basics.wmv

http://video.helifreak.com/?subpath=...3benchtalk.wmv

http://video.helifreak.com/?subpath=...gp4protune.wmv

Hope these can help you they really helped me.

Oh and sorry if posting these break any rules.

[sacko]

Break the engine in as said.

You dont normally need to play with the idle screw.

High needle first (larger one) - Start to do some big air loops or tic tocs etc. Start to lean the engine, you can use the backplate method, infra red gun or listen to the engine..

Mid needle next (smaller one) - Do a full pitch climb out, when at the top of the climb, listen to the engine transition from high to mid. Lean the engine accordingly.

Both my needles are around 1.5turns out, and thats running a bit rich but perfect for me.

[waveydavey]

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.

[sacko]

Thats the video I watched too

[Eckchaz]

Thats a great post Callum.. I'm going to break in my 91 today and I was going with the same tuning as the 55.. until I read the 10sec rules different for a 91!

I've got mine the nearly the same as Dave and Paul.. i'm finished on Mid/High on 1 1/3 (idle left alone) but thats only because I felt my 55 was optimum on just less than 1 1/4 so just that little richer. As Dave mentioned to me, when I first started and already mentioned, you need to get some heat into the engine, so make sure you get some power climbs through it!

[Mslater]

Break the engine in as said.

You dont normally need to play with the idle screw.

So your Idle is at factory setting ?

[Spanner]

I got it tweaked as well as I can, both needles maybe 3 or 4 clicks rich of 1.5 turns. Idle needle is still at factory setting.