Nitro Engine Tuning 101

[Finless]

Originally Posted by Doozer

Not so hot that I can't touch it, but hot enough that I can only hold my finger on it for five to 10 seconds.

This sounds about right to me.

Originally Posted by Doozer

I'm burning through fuel pretty quick... I'm done in about 6 minutes of sport flying. I bought this engine (and heli) used from a guy I know fairly well, and he only flew it in a cold wet climate at a higher elevation. I'm in Phoenix, the exact opposite. He was getting 9 minutes out of a tank.

Air density and humidity does change your tuning. Best performance is dense air with no moisture. Seems Phoenix would have those conditions except in the summer when it's 100F or something. Out here in CA I get about 8 minutes on my Trex600 OS .50. I am sure I could eek out a bit leaner mixture but I am not a 100% performance need kind of flier like Tim.

Seems to me you could lean it out a little more. Just watch out for the lean sound and if you hear it stop right away.

As for the backplate thing, even though Tim mentions the temp gun issue when it is really cold outside. On normal days in the 70's or so, a temp gun does help give you a head temp indication. Just be careful setting the need to try and get to a head temp in really cold conditions.

Bob

[Doozer]

I was just worried because Tim said something like you should be able to keep your finger on all day long.... "if you ever have to let go, you're running too lean." I got a little worried I was doing something wrong, because sometimes I can't keep my finger on it much more than 5 seconds. Anyway...I just went out and bought a new temp gauge. Thanks for the answers guys.

[gilligansc]

My hands are so rough, I can hold onto a motor that is hot from running lean....so temp gauge s the way to go!

[HeliBenj]

From my limited experience, backplate feel is not very accurate for tuning. If it's getting hotter than it should, it would be worth checking if the crankpin doesn't rub on the backplate, ie if the crankshaft (and rear bearing) is seated all the way without play?
Also you might get more help by posting in the engine section

[jogarce]

Bob,

do you have video on how to break-in this power house im new to this and im afraid to run this engine. I have already turn the high speed needle valve. And realized that a mistake so i have no idea how to.

jogarce

[360Wings]

Finally got around to watching this vid's.

Just wanted to say thanks to Finless and Tim for taking the time to shoot video and for your expertise.. I found it very helpful..

Cheers
360

[DanCopter]

Hi Tim/Bob,
Great videos! Good info combined with a good show of flying by Tim.

Just to clarify something. YS is typically a "set mid needle first" versus OS which is "high needle first". Will the 120 have a very different carb to other YS or is it that your technique of tuning, Tim is just different than YS say to tune?

Thanks again guys.

[Finless]

Well I think YS reccomends this mostly for new people learning to tune as to not "chase needles". So yes Tim is tuning the way he likes to do it and sharing with you all. I also tune my YS .91 in this way.

Bob

[wareck51]

Hi everyone

Bob,another time you made a great video would be help lot of people (like me).

I try this on my new heli and work great

I have a little question:
On your video, TIM show a product in a small tube for sealing hexaust (Hi temp epoxy).

I can't understand the name of this product...

Thank you again for your work.

Olivier
France

[Matt Nasca]

Bob or Tim,

Do you know what the in-air temp should be for a OS 91 hr-z? I have telemetry and in sustained tic-tocks (well maybe for 5-10 seconds) I'm getting up to 218+ F and in moderately hard 3d flying between 180-195F. Ambient temps 50F.

I know on the ground I've always heard 170-180 is perfect. What is the max you'd want to go in the air though? I'd love to set the alarm higher if I could, I'm hitting my 210F alarm two to three times a flight.

My sensor location below.

[Alfred]

Your sensor location is correct as it's out of the airflow.

Is your temp oK...the only way to know is pull the muffler off and have a look at the ring and sidewall of you piston.

[no.limit]

Great videos for engine tuning, they really help a lot of people!
Thank you Bob and Tim! Great work!

Now, I have a small question: when I apply max pitch and throttle (going straight up) and then stop the helicopter (to see what is the situation with the middle needle) the engine almost quits! I have no smoke at all, because the engine is almost shutting down.

Does this mean I am too lean or what?

[Finless]

Oliver the stuff Tim uses is:
PC-Farenheit Epoxy, which can be found at Home Depot or Ace hardware stores.
http://www.acehardware.com/product/i...ductId=2923266


Radduke, Manufacturer recommends no more than 220 F. Most tune to run about 200-210. HOWEVER with that said and just like Tim said. On really cold days this can be a false tune. Meaning you maybe too lean and not getting to say 190F. Dont try to tune to the 200F as it will make you too lean.

No Limit. If you not seeing smoke your too lean.

Bob

[Matt Nasca]

Originally Posted by Finless

Oliver the stuff Tim uses is:
PC-Farenheit Epoxy, which can be found at Home Depot or Ace hardware stores.
http://www.acehardware.com/product/i...ductId=2923266


Radduke, Manufacturer recommends no more than 220 F. Most tune to run about 200-210. HOWEVER with that said and just like Tim said. On really cold days this can be a false tune. Meaning you maybe too lean and not getting to say 190F. Dont try to tune to the 200F as it will make you too lean.

No Limit. If you not seeing smoke your too lean.

Bob

Bob,

Thanks for the response. Is that 200-210 while flying or after landing and temping?

Matt

[Finless]

Well most people before telemetry landed and while the engine was idling used a temp gun. Or they temped it immediately after shutting off. When the engine shuts of the temps will climb as cooling has stopped and the muffler etc holds a lot of heat.

I suppose with telemetry you could see some high and low spikes. Seems to make sense to see that live. But I simply cannot say what it should look like live as I have never done it.

Bob

[Matt Nasca]

Originally Posted by Finless

Well most people before telemetry landed and while the engine was idling used a temp gun. Or they temped it immediately after shutting off. When the engine shuts of the temps will climb as cooling has stopped and the muffler etc holds a lot of heat.

I suppose with telemetry you could see some high and low spikes. Seems to make sense to see that live. But I simply cannot say what it should look like live as I have never done it.

Bob

That's what I've always seen and they guys I fly with are usually 180-200 after landing. I see with telemetry, the temps are 30-40 deg cooler from a tic-toc to landing in a matter of 15 seconds.

The cool thing with the telemetry is that flying around aggressively it'll be between 160-180F then when you start hard 3d it'll climb to 190-200 and pretty much stay there until you do tic-tocs or low airflow, hard loading moves, then a simple punch out or rainbow will cool it from 225 down to 190 real quick. Then at landing the telemetry reads 170-180. at 50F ambient.

I'm 1 3/4 on high and 3/4 on mid with 30% RR and 91 hz-r and it runs strong there and I know it's not lean, but I can get the temps up to 225+ real easy! I didn't see how high it would go but based on how quick it gets there, I'll bet it would go a lot higher.

I was almost happier before when I had less information and it temped at 180 on the ground! lol

You should do a video with telemetry!

Matt

[Finless]

I dunno... too me what you are getting sounds OK.

Bob

[Matt Nasca]

Originally Posted by Finless

I dunno... too me what you are getting sounds OK.

Bob

Cool, thanks Bob. I just wanted a far more educated head on it; I feel better about the temps now.

Hopefully soon, we'll be able to see what some of the pros get for readings.

Also, thanks Bob, for all you do!

Matt

[Beaver Rat]

So how exactly would this method of tuning translate to a double needle configuration (YS 50 ST)?

[Finless]

I cant speak for the YS 50 as I never had one. On the OS 50 the idle needle (screw) and the high needle do effect the mid range as they work together. Some say do not adjust the idle needle. I find you can only if needed (idle sucks bad and quits all the time) but do NOT turn it much. No more than say 1/8 of a turn max. But do not mess with the idle needle right away. You just use the high and tune the engine just like Tim show but since there is no mid range needle you just have to adjust high and try to get a balance. Then and only then tweak the idle needle if you have to. If you do you will probably have to go back and adjust the high again to get the mid range running right.

Bob