bojangle

I break in all my engines per the manufacturer's suggestions. I figure they know best, and I want to preserve the warranty. In the old days, a well broken in engine was worth more than a new one, it was a time consuming task. Guys used to pay me to break in their engines. But times have changed, metals and manufacturing have improved, and I quote the instructions for my OS FS-70 4 stroke:

"O.S. engines are made with the finest modern precision machinery .......only a very short and simple running in procedure is required and can be carried out with the engine installed in the model". (But I still do a short break-in/test on a stand, I won't chance my planes to a finicky or defective engine )

As for the fuel, another quote from the instructions:

"Standard commercial fuel.....fuels containing castor-oil and/or synthetic lubricants are acceptable....5-15% nitromethane......16-20 % lubricant. " (no mention of special fuel)

Lately, several articles have appeared in various magazines regarding proper break-in and fuels. I wish I had never read them, according to them, I've been doing it all wrong. But even the experts don't agree. One expert says you don't want any castor in a 4 stroke, as it will cool the engine two much. Another says you need more castor for lubrication. Another says you need a special mix. Even the fuel manufacturers don't agree on this.

I agree with the concept of "heat cycling", (get it briefly hot then let it cool). This is contrary to the old school of simply running it rich till it breaks in. If the engine never gets hot, it will never break in. I use Omega 10%, castor and synthetic mix, in my 4 strokes. Please don't suggest other brands, I've been using the Omega for 10 years with great success. (If it ain't broke, don't fix it). I vary the break in procedure for Non-ABC, ABC, ringed, etc., and I break in 4 strokes similar to any ringed engine. I use the supplied type F , and Fox Miracle plug for replacement.

"Expert" statements: Castor makes the engine run cooler (exhaust stream will be hotter since castor carries the heat away). Not good for a 4 stroke, good for a 2 stroke. Synthetic lets the engine run hotter (exhaust stream will be cooler as heat is retained in the engine). Ok for a 4 stroke, not so good for a 2 stroke). So I figure a mix in a well broken in engine is a good compromise.

Comments, anyone? I would even like to hear from the fuel manufacturers. Omega doesn't list the mix in their "4 cycle fuel". Why? What's the big secret? Is it more expensive because they have added more castor, or because they have taken it out. It's sorta like, chili without beans costs more than with beans? Why should I be using or not using special 4 stroke fuel? I've been going along fat, dumb and happy for many years with no problems, but always willing to learn.

BO "Dummies have more fun, cause we don't analyze nothin"

DBCherry

My Feedback: (4)

Bo,
I run standard "2 stroke" fuel in all my engines and haven't had any problems. (10% nitro, 18% oil, some castor some synthetic.)

To paraphrase your signature line, have fun, don't analyze!
Dennis-

Tall Paul

I always add 3 oz of castor to each gallon of fuel I buy, and use the fuel in both 2 and 4 strokes. I'm not into ear-screeching rpm, I just like motors to last awhile.

rmh

When four strokes first hit the us -- the magazines had all kinds of erroneous talk about needed lubes - one article even intimated that oil may not be necessary-
some thought that beacuse it fired every other time -- it needed----half the oil .
some was ever worse info.
History has shown that you can't fool mother nature .
If the combustion pressure is higher -you get --ta da --more heat. strange how that works -
if you set the needles correctly - you can compensate for slightly incorrect oil/ alky/ nitro mix.
If you make the engine run loaded with a prop load that does not permit easy unloading - you again get more --- heat.
When it was all said and done (and I am done with these little buggers ) the mix is pretty much the same as any other high performance glow setup
enough nitro to make the needle adj smoothe and enough oil to satify a higher temp and enough castor oil to hold down rust - .
best all around mix we used was 20% oil blend (included some castor) and 20% pure nitro -and good grade (low water ) alky.
We ran some on only Klotz and alky and they ran fairly well .
early four strokers were way overcompressed .
Our competition blend for the OS 91 - was Magnum #5 on a 13x11 APC prop --turned 10000rpm
and the engined ran fine for a long time -when I finally sold it ,it was still in very good shape .
I also rebuilt many YS engines over the years - and these also liked this 20/20 mix.

bojangle

I can't begin to tell you how relieved I feel after reading your comments, 3 straight answers from guys with actual experience and success. Thanks DB, Paul and Dick, you guys are super.

Forgot to mention, I fly at about 6,000 feet. I haven't experienced any large detriment in power as compared to my previous sea level flying. But then, I'm just a sport flier, so not concerned with high performance either.

BO "Dummies have more fun, we don't analyze nothin" I have lots of signature lines, but this one seems to fit me at the moment. I don't really want to know a lot about 4 strokes, just enjoy them.

MinnFlyer

My Feedback: (4)

Sometimes I think Dennis and I have the same DNA.

I'll put a big ditto to everything he said.

DBCherry

My Feedback: (4)

Mike,
Sometimes I wonder if my Dad (or Mom?) made excursions that we didn't know about. It's a little eerie at times, how much alike we seem to think.
Dennis-

bojangle

I've heard that "Great Minds Think Alike".....hmmm, another signature line.
Maybe you two have been sniffing from the same Nitro jug??

Last night I was flying in about 20 mph wind, got a whiff of the exhaust fumes....ahh,
eau de nitro. I tried some Omega 15% in my FS-48, seemed to idle better, and transition to WOT was good, it's well broken in now. The 70 still needs some bench time I think. I have a 10 year old (still in box) Gemini FT-160, reserved for a built (not yet covered) Sig 1/4 Scale Cub. I am not looking forward to breaking that one in. I've had some offers on the plane and engine, haven't decided to sell, or even what price to ask. I'm too old for complicated planes.

BOB (reveals his secret identity) My two favorite forums are "Kit Building" and "Questions".
I used to read "Park Flyers", but almost lost my sanity lol. I figure when a Slow Stick starts looking good, maybe it's time to retire.

DBCherry

My Feedback: (4)

Not necessarily the case Bo.

I have a couple of the little electric park flyers. A GWS Cub and a GWS Tiger Moth, as well as a Simple 400. While I only fly them about once a year, they too have their place.

I had the little Cub at one of our club fields last spring and flew it in 8 to 10 mph wind that was steady right down the runway. The plane took off and flew the entire flight without moving forward or back more than about 3 feet. When I landed, I had to chase the thing down the runway as it tumbled away. Truly a riot, and the guys were laughing so hard there were tears in their eyes.

Sorry for taking your thread so far off track!
Dennis-

MinnFlyer

My Feedback: (4)

Bo, that 160 Gemini and the Sig 1/4 scale cub is a GREAT combo! (Clip the wing!!!)

bojangle

I was just kidding. We all have electrics here, including a couple Slow Sticks. I am amazed at the punishment the SS will take, and it is a riot when the wind gets fierce. Actually, I fly my electric several times a week. My front yard is a huge alfalfa field, I hand launch right out my garage door. Nice to get in a quick flight just before dark.

Well, I already have the Cub at full length (104") I have mixed feelings about finishing the plane. I built another one about 20 years ago, liked it but sold it when we bought the ranch. The 160 does look awesome in the nose. Guess I should start bench running it soon.

BOB

MinnFlyer

My Feedback: (4)

It's not too late. A razor saw and a little epoxy and you're good to go