It's been a rather lengthy process for me breaking in, and tuning my Zenoah G230RC. Many issues have come to the surface during the whole process. I'd like to thank James a.k.a. "Sparx" on Helifreak for the very good advice. You can't always get to a field and ask for help, and I've found that most of the heli guys in my area don't understand gasoline engines as they pertain to helicopters. You'll also find that the internet is full of advice on breaking in and tuning this engine. I've come to the conclusion that there is no "One" way to do it. Just keep in mind that these engines can take some abuse. They're built for it. Think about how much abuse your weed eater takes. Think about a 12 year old kid getting a goped for Christmas. Do you think he/she takes the time to break the engine in before trying to go the speed of sound.... nope.... doubt it. So there's no need for the white gloves when trying to break in and tune these engines. I mean, don't go putting sand in the gas tank, but they're tough and can take a little abuse.
So first lets talk about breaking in. There are so many theories on this it will make your head spin. The theory has changed many times, and is still somewhat a topic of debate. However, I don't think any of those theories are really wrong, or better, but more like personal preferences.
RatiosEvery heli has a gearing ratio. Generally this is done by taking the number of Teeth in the main gear, and dividing it by the number of teeth on the pinion. For this heli, I am using a 115T Main Gear ("T"= Teeth) and a 17T Pinion. This gives me a gear ratio of 6.76. All Motors and Engines have a "Power Band." This "Power Band" can be found between max torque and max power.
The power band for the Zenoah G230RC engines is between 10K RPM's and 12.5K RPM's using the stock air filter, and stock can muffler. With a tuned pipe it's 10K to 13K RPM's but produces more Horse Power. After 13K RPMs your power starts to drop off slowly and at 14K there are no more power gains on this engine in it's stock form. So in other words, your engine will run at it's maximum efficiency between 10K and 12.5K., and start slurpin' the fuel after 13K.
So a good optical tachometer and my son, I measure my head speed then multiply it by the gear ratio to get my RPM's. I can then set my throttle curves accordingly.
Example: Head Speed=1850 Gear Ratio is 6.76. Multiply those together and you get 12,506 RPM's. This is at the high end of the power band. Ideally I'd like a gear ratio that brings me into the middle of the high end and low end but there are trade offs to this type of set up. With my current gear ratio, I'll have less head speed at higher RPMs, or I'll have more punch a.k.a. on demand power. Best example I can give would be like down-shifting your car to pass another on a two lane road. When you need power quick.
With a lower gear ratio, I'll gain more head speed @ lower RPM's. This gives you a crisper head, but less punch when you need it. Example:
A 20T pinion and a 115T main gear have a gear ratio of 5.75. A head speed of 2200 gives you 12650 RPM's. It takes more collective to give you the same amount of on demand power that you get from a higher gear ratio. The upside is that you'll use less fuel at a higher head speed, and your engine will stay cooler as well. The best example I can give would be like Driving your car up a 45 degree incline in 5th gear. Eventually the engines gonna bog, but your really moving on level ground.
Needle SettingsI set bot the High and Low needles to 1 3/8 turns open from fully closed. This will not be your final setting, but it is a starting point. This is a rich setting and at first you'll probably get some gurgle and more smoke than you expected. This is not the factory setting. The factory is in Japan, and the needle settings are set for their climate and altitude. Yours is probably different. So close the needles all the way down (not too tight), then open them back up to 1 3/8. There is no dial spring like a nitro carb, and no dial to use as a guide, so your "spitballin'" a bit.
Fuel and OilI used Lawnboy Ashless at a ratio of 5 Oz. to a gallon of 87 octane gasoline. A few of the engine manufacturers are now recommending a full synthetic oil right away. When I started breaking this engine in, I was reading the FAQ's on helifreak. They are a bit outdated. If I would have asked first, I probably would gone with a synthetic right off the bat. There are those people that still believe you should break in with a non synthetic, and I'm proof that this way will work.
My way, you will get some carbon build up on the head of the piston. This is normal but kind of scary when you first see it. First thing I thought was F*ck, I'm breaking it in lean. Then I went here:
aboutkarting.com/piston/ My piston looked very similar to the first one. Which was perfect for the type of oil I was using. Sparx will be the first to tell ya, as he did me, that I was worrying too much. I agree. There's no need to check the piston at all during break in if you set the needles correctly. As a matter of fact, by checking the piston somewhat frequently, I ruined the paper gasket on the exhaust manifold. This caused a bigger problem later.
So if I had it to do over again, I'd start with a full synthetic at 5 Oz to a gallon of Coleman Fuel (more on the fuel later). However, you can do it the way I did it and be just fine too. If you listen to the engine, you'll hear the ring set in. This might take a bit longer with a full synthetic, but I don't think that's such a bad thing.
I've babied it for two gallons, but I from what I've read, and been advised, I'm pretty sure that's not necessary. These engines sip fuel. Babying them for two gallons will take a long time. Especially if you don't have a bunch of time to spend breaking it in. You can expect between 1.5 mins and 2 mins per oz of fuel if you break in easy. That's quite a bit of time if you do the math. Bill Meador (Billme on most forums) suggests that these engines just keep getting better over time... over the span of many gallons (up to 7,8,9 gallons even). However, he also recommends breaking in with an ashless oil for the first gallon then switching over to Blue Marble or a 100% synthetic. We'll talk more about that below.
Fuel TypesThis is a personal preference. Gas is very cheap. You can fly for hours on $2 worth of gas. These engines are gasoline engines and should run gas. However, there is a major downside to using this type of fuel... smell. It doesn't matter how careful you are, you're going to smell it. If you keep your heli where you keep your gardening tools, I'd use gas, but I like to bring my heli inside.
Coleman fuel is about twice as expensive as gas, but has an attribute that makes the extra cost worth it. It has a faint smell that dissipates in just a few seconds of exposure. I can have my heli fired up in the driveway and immediately bring it inside and not smell a thing. Another benefit to Coleman Fuel is stability. It can sit in a gas can for a few years. You can't do that with gas from the pump. Coleman will bring the per flight cost up, but it's still nowhere close to nitro or electric.
Some say Coleman keeps the engine cooler due to it's octane rating. I believe this is true. Some people say you need less oil in the mix. I think not. I'm still @ a 25:1 ratio, using Royal Purple Two Cycle Synthetic. My engine doesn't gurgle and runs very smooth. You'll see posts of people running @ 40:1. Eh... the extra ounce and half of oil is worth it if you ask me. I wouldn't risk a ratio like that... the oil just isn't that expensive, replacing your engine will be. I think the lowest I'll ever go with any oil is 32:1
The BEST oilI don't believe anyone really knows the answer to this. People try different oils with great success, and you'll have those that swear your oil is sh!t. I've heard and read it all. I honestly think you could run Lawnboy Ashless full time and be o.k. You'd need to clean your engine parts more often, but that's not always a bad thing. It's just a little time consuming.
The current trend is to run Full Synthetic Pennzoil Two Cycle Marine. You can use a synthetic Blend as well, though most SB oils are heavy on the "blend" and light on the "Synthetic." You'll still see some carbon build up with this oil, but it's perfectly fine to run in your engine. I know Kloner uses Klotz (Benoil) and his plugs look perfect
My advice, for what it's worth, find an oil you like and stick with it. Fly it and have fun.
TuningIf you try to tune inside the first couple of tanks while breaking in... stop. Set the needles @ 1 3/8 out and leave them there. You can adjust the needles so your engine isn't missing, but don't go too far. The important thing to remember is that this is not nitro. There will be little to no smoke leaving the exhaust, so you can't tune off smoke. The only thing you can use is your ear. If it's missing and sputtering it's rich. If you see the tail kicking, that means the engine is missing... it's rich. If you hear the engine get "raspy" and it takes a while to settle into an idle it's lean.
You'll literally hear your engine get happy. I'm sorry that there's no real way to describe that, but if you're not sure, it's probably not happy. You'll want to tune from rich to lean by closing your needles 1/16 of a turn at a time. Small moves go a long way, big moves will get you in trouble. You want to "walk it in" to a tune. Many things will happen when you start to get it tuned. Mainly, you'll see that it takes less throttle to produce the same head speed. When you start to lean the engine up you produce more power. You'll see that you're not consuming as much fuel, because when you lean your engine your adding air and reducing fuel. Your throttle curves will change during tuning. If they fluctuate too drastically, one tank you need 20% to hover the next you need 25%, that means your engine is still breaking in. Open the needles up a bit and ride it out another tank or so.
The key is to listen to the note of the engine. I live in the desert, and it's very hot and dry now. The rule for tuning is, if it's hot, you want to lean the engine. If it's cold you want to run it a bit rich. You can temp your engine if you want, I did, but if you do things the right way, it wont be necessary. Every engine is different, but when I temp, I temp from the head. The head has several cooling fins on it, and I hunted around on those fins until I found the spot that ran the hottest. I used that spot for temps from now on. Anyone that tells you there is a specific spot to temp from is wrong. You have to find it. An important thing to note is that not all thermal measuring devices measure the same way. Most of your infrared temp guns have a "field of view" that is 1:1. That means if you measure from a distance of 2cm's, the thermometer will measure an area of 2 cm's. Shoot from a meter away and it will measure a 1 meter area. The guns then average the temperature of all things in that field of view. Thermal sensors from telemetry style devices measure exactly what they sit on. So what's the problem? An Infrared gun averages, so if in your 2cm area it measures the head wall @ 300 degrees, but also one of the cooling fins on the head @ 200 degrees, you have and average temp of 250 degrees. A telemetry sensor will read higher. It's not uncommon for the temp from these sensors to read temps of 360 degrees.
I'm using a 17T pinion. Again that 's a gear ratio of 6.76. I like to fly this heli with a head speed between 1850 and 1900, so I have to run this engine close to 13K. Because I'm using the stock can muffler, max power is @ 12.5K rpms, max torque is 10K rpms. So running at 1900 will put me over that. 1900*6.76= 12.8K. Ideally, I would like to be running 11.5K rpms, but at this head speed I have oscillation and bobbing issues. However if you run the engine more toward the high end of the power band, you have less of a chance to bog below max torque. This is why I feel knowing your throttle curves is very important.
I think temping is a good diagnosis tool, but if you have your engine tuned by ear, and as long as you stay within the power band, your temps should be ok. Even though I've explained temping in some detail, I wouldn't put a much emphasis on temperature until you start leaning out the needles and running outside the power band.
Another way to check your tune is to check the plug. Like nitro glow plugs, we're looking for a milk chocolate or cocoa brown color. A black plug means your running rich, if you continue to run this way, you'll foul the plug (points finger at self). I did it twice breaking in this engine. You don't want to run pig rich. Some people suggest that this is o.k. but it's not. By running rich, your engine will miss and vibrate.
Vibrations are a part of flying helis, but excessive vibrations are the root issue of many crashes. Vibrations tend to back out screws with questionable amounts of thread lock, cause the head to shake, and cause problems with gyro sensitivity. "When in doubt turn the needles out" for sure, but don't leave them that way. If you're going lean with needle settings of H 1 3/8 and L 1 1/4 I would think you have an air leak somewhere. Watch the stock carb insulator manifold. It warps easy. I think you're better off switching to a billet manifold. Also, watch the paper gasket on the exhaust. Air leaks on either the intake or exhaust side of the piston will cause your engine to run lean... even at rich needle settings. Get some PC Fahrenheit Epoxy Putty and replace the paper gasket with that. You'll be glad you did.
