Today was the day I broke in my ST 90, China made. I was a little skeptical at first but what a jewel.
Broke it in on one gallon of Omega 0% nitro, 17% 70/30 syn/caster oil blend fuel. Added 114 ml of castor to bring it to 20% and a 13x6 prop.
14oz Tank.
Run rich, 3 turns out, on first tank.
2nd and 3rd tank, 2 1/2 to 2 1/4 turns out.
4th and 5th tank, 2 1/4 to 2 turns out.
6th and 7th tank, 2 turns with the pinch test.
8th tank, 2 turn and finding optimal setting with tach.
9th tank, set the idle.
Now I must say this engine got stronger and stronger. Has great transition from idle to full power and the mid is fine.
You could definitely tell it was breaking in great with the different rpms it would run through.
Keep in mind this is with the throttle set at full open.
It never leaned out totally and ran flawlessly.

You wasted a whole gallon of fuel on break in? Why? I spend a couple tank fulls "properly" adjusting my engines and then fly it. Everything else is a waste of fuel and flight time. A person can run 5 gallons through and engine but if its not properly dialed in, whats the point of it. All that waste of time and fuel is not going to make it run any better.

Maybe it was worth it to be confident that the engine was broken in properly and running reliably....

Maybe it's been a long winter and it was fun to just get outdoors and run an engine....

Good flying,
desmobob

nice breakin report mickeeand. different people use different breakin procedures, as cyclic describes. but the g90 is a very good engine regardless of the breakin.

ed

Have the same engine, NIB, for a p47 Thunderbolt. Hope it runs reliably ... Lots of work going into this baby

Regards,

Misterpanda

Have the same on a UCD 46, punched the baffel in the muffler and put an OS carb on it. I run an ACP 14x4 wideblade on 15% nitro 20% Castor/ Syn. I must say it works well and power is not an issue. A nice engine that works well, a good value.

A gallon of fuel is much cheaper than a 90 size model. I've got 3 gallons through my 2300 and still won't put it on the plane I bought for it. Gotta be confident in the powerplant! They do run better the more they are run. Especially for the first three gallons.

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Were he running an ABC engine, I would agree with you, but he is not. He is running a ringed engine.

This is one area where helicopter experience will shoot you in the foot. Airplane engines do not run grossly rich in normal operation as helicopter engines do because of lots of nitro at a screaming rpm.

He did it just right as far as I'm concerned. Now he doesn't have to worry about how the engine will turn out. Of course, the engine isn't fully broken-in as yet, but it is close enough to fly-in the rest of the way.

True I probably could have just run a tank or two but what fun would that be?
Everyone does their break in a little different. I think its worth the extra time and money to really break in an engine well.
So the fuel was 8.99and the time was a few hours but it is worth it. I am a patient person.
I've never had a model engine not run properly because of this type of break in.
ST require a lengthy break in, its ringed. ABC's not so much.
Anyway it was fun to watch all that smoke billow from it.
Its still not totally broke in but at least I know its reliable before I fly with it.

Mike

There is nothing wrong with it, I just feel its a bit much. I don't just slap it and go but i run a 2-3 tanks dialing it in which also helps in break in and then just fly it. The length of time you spend breaking it in does not mean the engine wil run well , if its not tuned right.

How many people do we see here spend weeks and months breaking in their engines too make sure everything is right. If they don't know how to tune an engine, whats the point?

mickeeand,

Great to hear you like yours, I have one to go on a Goldberg Extra 300 (the old biy kit). I also will run mine up on the stand, when the weather warms up. The fit and finish is impressive, hey it was only $114 when I got it from tower, a lotta engine for the buck.
If this thread keeps going I'd like to hear how it performs when you get to fly it.

Good luck,

Pete

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Actually, we see lots of people here complaining about this or that junk engine and about how they are going to dump it for an expensive OS. These folks do not understand that a ringed engine takes a while to come in and that it is not just plug-n-play, UNLESS it is an OS ringed engine. However, I do not see many old OS ringed engines around that are still running on the original ring, as I do with Super Tigre, Enya and a few others that use rings made of harder material.

Many ringed engines, when they are not broken-in, will overheat and quit. If you do a survey of all of the posts here that complain about this exact thing, the picture becomes a lot clearer as to what is going on. Insufficient break-in time/procedure and too much nitro in the fuel are the two biggest mistakes that newbies make. One can buy an OS with a soft ring and get away from this syndrome, but then their engine's ring will not last as long as those that take a longer break-in. You can't have it both ways.

Well, I am not a newbie to the hobby. When I first started in the hobby my teacher taught me how to tune, break in and run various types of engines. I definitely dont just buy and engine and put it in a plane and run it.

mike

Cyclic Hardover: I think I should pass my title over to you! hahahahahaha!!!

I'm sure I don't know what you are talking about. I've never heard of this being done. An engine that has problems just might require a little more ground running before being mounted on a model. Without the pressure to "get it in the air", there is ample opportunity to get it tuned properly. If it gets broken in during the learning phase, that's just a bonus.

This is where I disagree-sort of. Ed is dead on the ring engine getting better as it gets some run time. I don't believe for a second that and engine that is having problems needs more run time. Why? the problems will still be their when you get done. If an engine is having problems, I feel is a "skill thing". They can't tune the engine any better than a redneck can tune a fork? I have no idea what that means, it just sounded good.

I have them all OS, ST, Jett, MVVS, and others. All run great. My main sport engine of choice is Super Tiger. Why spend $250 on a 91fx when I can get equal or better performance and reliability for $120. If I want High performance, I go with a Jett. None of these engines are any better than the other if you can't dial them in right.

Breaking these in on 5 gallons of fuel (to me) is a waste of time and money. Then we see here , the all too common scenario of my engine is doing this or that, the answer? Get a Pump. Oh sure like thats going to solve your problems. So now he has a pump on an engine and he still can tune it properly.. Lets add a glow driver, some $50 glow plug and the right prop this time. Some i4c electronics and onboard computer.

Maybe that computer will finally tell this clown what his problem is.

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I do agree that tuning skills are paramount to obtaining proper performance and that some of the problems newbies experience are directly attributable to improper tuning techniques.

Yes, an experienced engine man can fly-in an engine much earlier than one that is just learning the tricks of the trade. But I enjoy bench running engines and really keeping an eye on the engine while it is breaking-in, so I am biased in that direction.

Just what is your point in making such a remark? You speak as if all engines are great engines, and if they don't run right, it's because the nut turning the needles is a moron. It's just not the case. Some engines, for whatever reason, are a pain in the but to get running properly. And there are some that will never run right. You must have bought all the good ones. I've had a few that were nightmares. I've had others that were simply amazing. It's not always the user. [sm=devious.gif]

All the guy did was post a report on breaking in his engine. He must have enjoyed doing it, and he must have been happy with the way it turned out.

Why do you keep implying that he --and everyone else but you, it seems-- is incapable of tuning an engine?

Good flying,
desmobob

It was getting late at the time. I definitely agree that all engines are not great. The 91fx comes to mind. Although I have several other sizes of the OS line up, it is my personal opinon this engine is crap.[X(]

On the lighter side, had it not been for the 91fx, I never would have fallen in love with the 1.08.
Go two of those puppies. So, from the bad, comes good.

Took my Shoestring out the other day for the first flight of the season. G90 did real well.

Maybe i just took it the way it was implied, that with such a long break in, that the engine will now run perfectly and thats a false assumption. And I am very good at tuning an engine, not because of a massive ego, but that I pay attention. After taking bits from the manuals and advice from others, I tossed the useless stuff and went with what makes sense and it works.

Breaking in an engine on 1 gallon or 5 is not going to make it run any better or worse if you can't tune it right. With simple back up checks, you can have a perfect running engine.

9 out of 10 times, I see people tune their engine and then pick it up and point it in the air, That nice but does not tell you much other than if the engine does not quit at that moment, it probably won't in flight but that still doesn't mean its running at its best.

Mickeeand,
It is your fuel and your engine, break it in any way you want. If you are happy with the way it is running and had a good time breaking it in on the bench, then, good for you.
Enjoy the ST90 as it is an excellent engine and will give you good service for a very long time.

Regards,
doubledee

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In the vast majority of instances, it is the user. I have seen very few truly bad engines over the years. I've seen a few that needed special handling, but it wasn't anything that an experienced engine user couldn't handle.

By the same token, everyone has to begin learning at some point, so each and every one of us has had a period when we were not good at diagnosing or tuning glow engines. There is nothing wrong with being a beginner. We all do it, but some folk's egoes are so big that instead of admitting that they are stumped with a problem, they insist that their engine is junk. Many of these folks think that if they throw money at the problem that the problem will go away. Most of the time this just isn't the way that it works.

One of the biggest problems that newbies have is unrealistic expectations of an engine. Newbies get together with other newbies and they swap stories and expectations. Soon there is peer pressure developing to have an engine that does this or that, whether any engine is capable of doing this or that is never considered.

A glow engine will never run with the predictability and steadiness of an electric motor. At this point in time, no electric powered model can compete with the power-to-weight ratio of a good glow engine. Maybe someday, but not quite yet. I see some folks with previous electric experience becoming incensed when their glow engine quits. Folks, that is just part of running a glow engine. No glow engine will remain running if the glow plug element is spit out of the exhaust port. Is it the engine's fault if the glow plug fails?

I am not saying that you hold the views I have mentioned, but a lot of folks do, and it is costing them some enjoyment of the hobby. They do not know any better. It is up to the rest of us to educate them.

What a nice, fun breakin. Are you saying you went to full throttle right from the get-go? For some reason I would not have thought of that for a ringed engine, but running real rich the way you did maybe it makes sense.

Which APC W (wide) prop is best for the G90? I picked up a 15x4 for mine, but see that Gizmo is ising a 14x4W. Perhpaps the 15 is too much?

thanks,

Ernie

The `15x4 also works well, just had some 14's around, the 15 spools up a little slower.