OS 50 Hyper - Tuning Problem

[Rotor Ruiner]

Hi all,
I was hoping some of you could shed some light on this for me. This is my first nitro heli, Kyosho Caliber 5, Stock Blades and OS 50 Hyper, Stock Kyosho muffler.
I can't seem to get the engine to tune properly, it runs well, but always seems to be running rich. I broke the engine in with the factory idle needle setting and 3 turns out on the main needle while keeping it well under 200 degrees. Just idling and low hovering for 6 tanks of fuel. Then set the main needle to 2 turns out for 3 more tanks hovering and mild flight. Last flight it was only 1 1/4 turns out still seemed to bog the engine when full throttle was applied from a hover. Inverted hover is nice but the climb out is really slow.
Pitch is set -10 to +10 dead on for idle up and -4 to +10 for normal mode. Everything is smooth and perfectly balanced, I checked everything in the driveline three times now.
Any help anyone can offer will be appreciated, I don't want to burn my new engine up.

[Motions]

Engine tuning is about the hardest thing to tweak on a forum. Too many variables (ambient temp, humidity, altitude, fuel, muffler). The best thing you can do is to check the engine temp right after landing. For a Hyper, around 220°F is an ideal operating temp. If you can hold your finger on the backplate for more than 3 seconds, it's about right. If you you can hold it on there for over 10 seconds, it's probably too rich.

If in doubt, run it on the rich side. 1¼ turns should be about right or maybe even on the lean side so I'm not sure why it would be bogging, especially at 10°. Can you explain how much "bogging" your talking about? How much RPM are you losing?

[Rotor Ruiner]

The machine under full throttle from a hover, sometimes seems to lose all power for a second (almost sounds like it quit) then screams up and the bird takes off with a load of smoke. I realise that this sounds like it is still rich but I am scared of burning up a new engine by running it too lean. Also should a nitro heli have as much climbing speed inverted as it does normally? My Trex with a aon brushless has about 80% of it's normal power during an inverted climb.
Thanks for the prompt reply, the hottest I had the engine is around 205 degrees.

FYI, I am an engine machinist, we build 700+hp turbo motorcycle drag racing engines for a top competitor. I know how hard it is to help tune an engine without seeing and hearing it. But that said, nitro 2 strokes are new to me. Thanks again for your help.

[Motions]

How is the low end running? How many seconds do you get on the pinch test?
It sounds like it's bogging pretty bad but if you at hover and punch it, it may be the low end that's rich also.

You should have the same climb out rate inverted as you do upright. It's really hard to judge on a Trex because the links and pitch are almost never perfect and usually have some level of play in them. It's also hard to get the pitch accurate because of this and the size of the model.

[Cncguy]

I agree with Motions that the problem may be the idle circuit. Its possible that the high speed may be too lean. You should probably screw the high speed needle out a 1/4 turn before leaning in the low speed to be on the safe side.
I think that the OS instructions says that the mid range is adjusted by a combination of the high and low speed needles.

I am also an engine machinist for Fuel Injected Sprint Cars
We need a chassis dyno, 02 sensor and a data logger so we can tune these Heli engines more easily. LOL

[Rotor Ruiner]

I never did a pinch test. That is where you pinch the fuel line to see how long it runs for right? I leaned it out 2 clicks more and climb from hover has improved. But now when I start it, it won't idle without me giving it a little throttle. When it will idle without more throttle it usually stalls out before I can carry it out onto the field, approximately 30 seconds or so. Ok I only have about 1 inch of fuel line between the filter and the carb and 1 inch on the other side of the filter to the tank. Where should I pinch it, and how long should it run for? I have heard anything from 3 seconds to 7 seconds. If the low end is really rich, I assume it will cut out almost immediately. One last thing, if I do go too lean will the engine start "popping" and "crackling" under heavy throttle, like a motorcross engine will? Thanks all.

[tdswan]

The how-to section in the home page of this site has a good tuning technique. I used it to finally get my Hyper happy. If it's quitting when you go set it down, you're too rich on the low needle, though.

An answer to your other question: Yes, it will pop a little if it's WAYYY too lean.

[Rotor Ruiner]

Just read the article about tuning the carb. I'm going out while I still have some decent daylight to give it go and see what happens.

[Rotor Ruiner]

First off, I live a 5 minute walk to a flying field which is really handy. I help out the guys that run it and I can come and go as I please. Well I followed the article that RC Heli put out that somehow I missed while reading it. Let me tell you, those guys know their stuff. After tuning for about 10 minutes, I load tested the batteries and filled it up with cool power 15%. This thing is a ROCKET ! I had no idea that a 50 could move so fast. The only other 50 I've seen at the field is a Raptor that the owner would rather shine up than fly. When it does fly it is low and slow. Both needles must be dialed in now, the sound was awesome and inverted climb outs unbelieveable. Like I said it's a rocket. You guys have probably seen a well tuned 50 but this was a first for me.

Thanks to all that pitched in some advice and especially the guys at RC Heli, you've just earned yourselves a new subscriber! The sun is going down now, I'll bet a burn a full gallon tomorrow.

[tdswan]

I, like you tried many other methods to tune my bird up. The RC Heli way was by far the easiest method I ran across. Just watch the temp on the backplate from time to time, weather changes will change your mixture needs!
Great to hear things are going well. Good luck!

[Felony44]

i had the same exact problem with my hyper right before it would come off the ground for a hover it would bobble real bad then smooth out. I havent played around with it that much but now i will go back and use RCs tips for tuning and see if that makes a difference for me to.