Yub, yub, cmdr!

I read in Model Airplane News that for the os .46 FX you needed to 4-stroke it, turn it off, then two stroke it. (of course I don't own one)

So you can make your 2-stroke a 4-stroke? or vice versa?

Kenny R

You can run a 2stroke engine so rich that it fires every other stoke or "4 strokin".

A 2stroke is a 2 stroke and a 4stroke is a 4 stroke. The dont swap back and forth.

nilo

Well, I guess there is some missunderstanding here.
2 stroke engines are fisicaly different than 4 stroke ones, so there are no way to turn one into another.
Well, if you change the timming of a 4 stroke engine(valves), it could even behavior as a 2 stroke, but completely unstable and unusefull.
For 2 stroke engines, there is a fuel ignition everytime the piston reach the max compression. The exausting and fuel admission usually are done by windows on the cilynder. This process waste fuel.
On 4 stroke instead, the whole cycle is done in 4 steps. Fist the piston compress and ignites the fuel, 2 the piston is pushed back by the explosion, 3 the piston goes again like step 1 but now exausting, 4 the piston retuns sucking fuel, then reapeats the step 1. This process uses valves to control the exaust and fuel admition sync and are more efficient.



Nilo

Dewey2

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ALSO DON'T RUN 4 STROKE FUEL IN A 2 STROKE DANG YOU ENGINE EXPURT AT THE FIELD IT WON'T HURT IT YEA TELL MY POOR OLD ENGINE THAT

Dewey2

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ALSO THE WINDOWS ARE CALLED PORTS IT ANT COOL TO WALK IN THE SHOP WITH ENGINE IN HAND AND ASK FOR A WINDOW JOB

nilo

I guess there are some keyboads missing keys being sold today.[:@]

Dewey2

My Feedback: (24)

DON'T HAVE TIME. WITH MY MEANINGFULL LIFE NOW.[:@]


PEACE OR WAR

I VOTE WAR YAW

NOPE NOPE NOPE . ALL KEYS ARE HERE IT BETTER BE I PAID 249.99 FOR MY COOL MEANINGFULL KEY BOARD. BECAUSE I DON'T HAVE TO USE A HAMMER TO TYPE WHAT I WANT TO SAY.

AND[:@][:@] TO YOU TO .

MikeL

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It's not wise to make an ABC/ABN type engine run that rich. If the engine doesn't come up to its designed operating temperature it puts quite a bit of stress on it. For a ringed engine that's a fine method, but it'll kill an ABC/ABN type like the 46fx.

spokman

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Why does OS recomend you run it like that then?

MikeL

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That's a pretty good question, as in the manual they also state that the break-in "allows the working parts to mate together under load at operating temperature." The instructions they use in the 46fx manual are generally how you'd break in a ringed engine, while in their 46fx-h manual (which is a ringed engine) the procedure they describe is what you'd generally do for an ABC/ABN type engine. Interesting, isn't it?

DBCherry

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I've wondered if OS is just trying to shorten the life span of their engines so you'll buy another one sooner.

I mean, I have three old 40 FP's that have a LOT of run time on them, and they're stronger than ever. I guess if our engines last 15 or more years, they won't see enough sales.

Seriously guys, the worst thing you cn do for an ABC/ABN engine is to run it slobbering rich.

Prophanger,
You say you don't have to pound on your keyboard with a hammer, then WHY DO YOU HAVE TO YELL ALL THE TIME!?
Dennis-

zetor

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Why will that cause a short life for an engine?

MikeL

My Feedback: (3)

A rich 4-stroke won't allow the engine to get up to its designed operating temperature. That's critical in an ABC/ABN type of engine where compression is derived from the different metals in the cylinder reaching the proper temperature. There's a slight taper in the cylinder, which explains the "pinch" you feel when you turn the engine over by hand. Notice that the pinch is much less when the engine is hot? That's because it's closer to its designed operating temp. If it's run too cool (as it would be in a rich 4-stroke) that pinch will cause a lot of wear and tear. When breaking in an ABC/ABN type engine you want to make sure it reaches that temperature quickly and holds it for a while. I'll usually run through a tank slightly rich on the test stand, and then go fly it. They're very simple to break in.

Ringed engines aren't nearly as common today. They use a compression ring, which isn't as sensitive to heat but needs to be properly seated prior to being leaned out and run hard. With a ringed engine you'd use a rich 4-stroke at a relatively low throttle. That puts less stress on the ring and plenty of lubrication.

zetor

My Feedback: (2)

Thank you that was a good explanation and makes sense.

rcjunkie50

another newbie here..

I just saw this thread and I do have a question for the experts here. I am new to flying and have not started the engine yet (Alpha Trainer), but have been doing cars and trucks for years. I have rebuilt the RC10 GT and have a new OS 15 in it. The break in for this engine is considerbly different than the manual for the Evolution 46. Why the difference?

Thanks..
DennisP

Dewey2

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because he can't lisen to nothing right the first time. i only yell when i have to. i most of the time yell anyway i'm a kid so loud music, airplane ,quads, and bikes keep my ears pretty much num all the time .

DBCherry

My Feedback: (4)

rcjunkie,
Well I really couldn't say, but it would help if you told us what the recommended break-in procedure IS for the OS 15. I'd only be guessing on break-in for the Evolution too. We "experts" really don't know everything.

Seriously, I've never run a car engine in my life. I'm sure there's someone on this board who HAS, and has also broken in an Evo 46, and could therefore answer your question.

MikeL,
Thanks for the answer. Not sure I could have said it as succinctly.
Dennis-

Yub, yub, cmdr!

Oh well.

I thought I could make my engine a FourStroke!!!

rcjunkie50

DBCherry,
The truck engine recommends several tanks rich, moderating the throttle before wide open. The evo recommends wide open then cool down repeat.
I think that the truck uses a wider power range than the airplane, on and off throttle vs half throttle and idle.

Any thoughts..........

DennisP

Jim Thomerson

Many who fly CL stunt like what is called a 4-2-4 engine run on a 2-cycle engine. The Fox stunt 35 being a primo example of an engine which will do same. Basically the engine is set rich and does in fact fire on every other stroke, i.e. 4-cycles. Power is about 75% because of enriched charge when the engine does fire. When the engine is loaded in maneuvers the increased load makes the engine shift to a 2-cycle with an increase in power when needed. There is a lot of fiddling with compression, timing, venturi size, etc. etc. to achieve exactly the pattern of run the flyer desires. Personally, I either run in a rich 2-stroke all the time or run a diesel.

Jim

combatpigg

My Feedback: (3)

A break in tip I learned from the pylon racing crowd is to put on a prop that is 2 sizes below reccomended for the engine [8-6 on a .46] and run it at a high rpm with the richest 2 cycle setting. Let the engine completely cool between each run of about 2 minutes. Break in fuel should have additional caster oil if you are using fuel with an unknown oil content. Do the break in runs with the muffler off also. When you are running the engine, pinch the fuel line briefly to make sure that you aren't running too lean, there should be more RPM with a quick pinch. As the engine breaks in, the needle position will need to be richened, because the fuel demand goes up when the compression seal is established. Once the engine is broke in , a high speed needle setting should be done with a near empty tank and the nose pointed up, this simulates a worst case scenario in the air. There should always be a fuel line pinch test done, with a few extra RPM on tap. The hot shot tuners use temp probes which are becoming more affordable.It's easy to "cook" an engine that you think is broke in if you don't pay attention to the sound it makes in the air. Your sport engines don't tend to be set up as tight as a world class hi perf engine, so you can run them richer with out stressing the conrod when cold. EXTRA CASTER is the most important thing to remember for longevity. RC JUNKIE!! Break in is an inexact science and it is not as critical nowadays on most sport engines. My breakin procedure for OS is to bolt it on the plane as quickly as possible and to start having fun as soon as possible, just pay attention to a lack of vapor trail out the exhaust, and sagging sounds at WOT. Remember ,EXTRA CASTER OIL!