Tired Old Man

My Feedback: (1)

Perhaps someone will turn this into a "sticky".

Seems that there is not a day that goes by without someone posting how they are having problems running their recently acquired new or used gas engine. A fair number of those posts also note the engine carb needles are still undisturbed from the "factory settings".

There is no such thing as a Factory Setting!!! Once people finally understand that every engine, regardless of fuel type used, has to be tuned by the user to obtain optimum performance, a large number of engine problem posts will go away. Any setting a carb has when it is first obtained had one of two reasons. The first is that they were enough to get the engine to do a test run at the factory. The only reason for that test was to determine that the engine would indeed start and run after the manufacturing process. It was not performed to check the performance level of the engine or to set it up for the end user. The second reason carb needles might be set in a given position is because that's just where they happened to end up when the person assembling the carb inserted the needles.

Factory Settings mean nothing and should never, ever, be relied upon to fly a model. Ever! You must tune each and every engine to obtain the best and most reliable performance. Changing propellers and oil ratios also generally require that an engine be re-tuned. As an engine completes it's break in process, which spans many gallons of fuel, the engine will require further tuning. Quite often a new engine will be tuned several times during the break in process as conditions inside the engine change from "wearing in". After the break in is complete the engine can be optimally tuned and will likely not require further tuning until the user changes another factor that influences an engine.

If setting up an engine with cannisters or tuned pipes, the typical tuning process is quite a bit more involved and can be very time consuming and expensive. The user will not be limited to simply adjusting the carb needles. Header pipe lengths and prop sizes will also have to be experimented with in conjunction with carb adjustments.

In closing: Tune your engine and you will eliminate many of your problems. And ours that frequently repeat this message.

Pat

Gremlin Castle

My Feedback: (14)

It will just as likely turn into a *****ley subject rather than a sticky. A fair number of people have huge misconceptions about what constitutes a factory.
Almost all low volume product is hand assembled usually in lots. The automated continuous flow production lines are not to be found in products that only sell s few thousand per year.

The Brison engines as an example were put together by the owner, his father,and sometimes a high school kid working part time. Their entire facility was not much larger than my living and dining room area combined.

What does this have to do with Carb adjusting? They bought the various model carburetors in lots of 20 or less and purchased the next lot when next needed. As such their carbs came from many production runs and each was set to make the engine run on the test bench. Depending on the particular tolerance stackup the needles in the carbs might be anywhere from 1/2 turn or less up to past 2 turns open to get the correct settings. So just like flying, you move things enough to get the job done without worrying about a "factory" setting.
The only time settings should become a issue is when a major change has to be made to something that has worked well previously.
You are correct about the tuned engine eliminating many problems. However, there are many that expect the engine to be a plug and play device just like their radios.

ec121

My Feedback: (2)

Boggles the mind that modelers would buy an engine and expect it to be perfect from the factory. They trust the little Chinese fellow to know their altitude and humidity while he is assembling their engine. "Run at the factory" means that they got it to pop over a couple of times to see if the piston would move.
We have a fellow in our club who says he has never had to balance a plane. Just assembles them and flies. He is either really lucky or assembling a terribly nose heavy plane.

gboulton

My Feedback: (15)

I hope so!! Well said, as always, Pat!

<br type="_moz" />

JOHNS3D

My Feedback: (5)

Pat is correct, i remember him saying that most carb. should be a 1 1/2 for start point and then begin to tune the engine.

av8tor1977

My Feedback: (6)

A much needed post...

AV8TOR

Super08

My Feedback: (2)

Another thing that gets me is many people never check to see what the needles are set at when they buy it. They assume they are set at the recommended "factory settings" and leave it there and try to fly with it. Of all the engines I have only one or two were actually at this so called setting. Some were so lean that it may cause damage trying to run it where as others were open to the point the spring had no pressure on it. One of the first things I do when I receive an engine is to screw in both needles and set them. The other is to check the timing.....

Truckracer

My Feedback: (19)

I don't own an engine that I know how many turns out any needle is set at. Could care less for the most part unless they are outside of what I would call normal adjustment range. I set them where the engine runs best and usually don't have to mess with them much from there on. A bit richer when cold out, a bit leaner when the weather is hot out .... good to go. People sometimes ask what my needles are set at and I just have to shrug my shoulders as I don't know. Just have to tell them to set at 1 1/2 to 2 turns to start and adjust from there. What could be simpler.

As far as I'm concerned, factory settings are just where the last guy at the factory left them before he boxed up the engine to ship it. Meaningless otherwise.

pe reivers

Not to be negative about factory settings. If the factory sets the needles, as most do, the engine will start and run for sure if the dry carb is primed and limbered up first. The sureness of running means that both needles are too rich! A gas engine is much more forgiving of rich settings, than of lean settings.
Today I had an interesting case with following symptoms:
The engine ran fine at full throttle, started extremely well, but in flight ran burbly at all setings 3/4 throttle and lower. It shook quite a bit at idle.
So I leaned out the idle until throttle response became poor. (about 3/4 turn) Then programmed in 0.5 seconds slow on throttle stick to make response OK again for stick horsing.
Engine was running well now, except for 3/4 throttle, which still had unacceptable 4-stroking (burbles, misses) in flight.
This was cured by leaning out the high needle little by little, and test flights. The carb had a static tube reference pressure, so that was one thing less to worry about. The H-needle needed 1/2 turn to almost eliminate the 3/4 burble, so against the wish of the now happy pilot, I leaned an extra 1/4 turn on the H-needle.
On cool down, the engine was re-started. It now needed choke to do so, where before it would start first flip. Throttle response was good enough, slightly lacking when still cold. Once warmed up, the engine ran smooth at all settings above 1/3rd throttle. Below that, no two stroke engine runs without misses. The pilot then flew many low power low passes without missing a beat. He clearly enjoyed the new feeling and reliable power that his plane had.
The engine could run as low as 790 rpm  with a heavy prop and spinner for as long as 5 minutes. Subsequent horsing the throttle forward produced full rpm without a single hickup.

Tired Old Man

My Feedback: (1)

Now you did it. You posted a value for an idle rpm. From here on out you get to be the one to answer all the questions about what rpm idles should be set at

As for a factory setting the needles of a carb for a good start up, I only know of one that does that most of the time. Perhaps MVVS does as well but I will never be one to depend on an engine running out of the box without verifying the carb needle positions. Those that do must like flipping propellers for extended periods of time.

Super08

My Feedback: (2)

That was the point I was making....When I said I set the needles, it is not to "factory", it is to 1.5 or so and tune from there.

Ralph White

T.O.M.

Thank you for this thread.

Perhaps the reason some modelers think that the gas engines come with the needles factory set is because they think that the model gas engines are modified weed-eater engines. The last weed-eater I purchased had needles that could only be adjusted with a special tool which means the needles are supposeably set correctly when purchased. I could see how some would think that perhaps the model engine is pre-set also. Of course the first really hot or cool day the weed-eater engine does not run correctly.

When I was first told that the needles on the model gas engines were pre-set I was very skeptical. I should have know better.

Again, thank you for all the help you and others provide on these forums.

Ralph White
Neoga, IL

Ralph White

T.O.M.

Thank you for this thread.

Perhaps the reason some modelers think that the gas engines come with the needles factory set is because they think that the model gas engines are modified weed-eater engines. The last weed-eater I purchased had needles that could only be adjusted with a special tool which means the needles are supposeably set correctly when purchased. I could see how some would think that perhaps the model engine is pre-set also. Of course the first really hot or cool day the weed-eater engine does not run correctly.

When I was first told that the needles on the model gas engines were pre-set I was very skeptical. I should have know better.

Again, thank you for all the help you and others provide on these forums.

Ralph White
Neoga, IL

tkg

My Feedback: (1)

I get a lot of engines for "make runs". I'm at 6000 ft ASL. When a simple carbed engine is run at a higher altitude it goes richer as elevation increases. So any body want to guess how many of the engines I get with, what the owner swears are correct, "factory Settings" that are too LEAN???

Truckracer

My Feedback: (19)

Agree completely with you 08!

The real problem here is that many posters don't read down the page for thread titles before they post a question. Most times, the answer they are looking for about their engine is already answered within the first few pages of threads. They are just too lazy or perhaps too uninformed to read down the page a ways or to do a simple search to see if the answer is there.

Case in point .... even before it happens. Mark my words here ... within the next few days, there will be a post about a crappy running engine that is still "proudly" running at the factory settings. And this thread will be just a few down the page. Am I wrong?!

willig10

Guys, I went to the field the other day and a guy was sitting there with a brand new airplane and I asked how's it run? He said it was not running very well. I asked him what was going on and he informed me that it was idling poorly. The first thing I asked him was did you re-adjust the needles. His response to me was the needles were set at the factory. I informed him that the needles needed to be set for our elevatiion and atmospheric pressure. I said have you tried to lean out the low end to get a steady idle and smooth transiton to High end. He said he had "past" problems doingthat with other enginesand did not want to adjust the needle.

It is my experience that most people are just plain afraid to adjust a carb. I told the guy I would be more than happy to help him adjust the carb for him and he declined. I waited and his buddy showed up and he wouldnt let him adjust on his engine either.

So in summary I guess you can lead a horse to water but you can't make him drink.

I would pose a guess that some of the previous posts are correct, that we will see more of the same questions being asked over and over again. I am guilty as well of not doing my research but am getting better (I hope) of not bothering you guys unless I simply cannot find the questions and answers I am looking for.

I have to thank JediJody, Antique and tired old man for helping me out and numerous others ( sorry I forgot your names) for helping me out on my timing issue earlier.

Bottom line to New guys to gas engines is this:

Always always always Adjust your needles. Always always always check your timing.

Preflight your engine before each flight. A little hairline opening in your fuel lines will make the engine behave differently. loose carbs and cylinder heads have an affect as well. Do your due dilligence and your engine will pay you back.

These are not the 2 stroke engines that are maintenance free. You will have to work and tweak on these engine continuosly. It is just the way it is.

Dont be afraid to tweak, tune and learn the in's and out's of your engine.

Oh well I am a newb as well but know a little bit about tuning. ( I'm a gear head).

Let me get off the soap box.

Glenn

</p>

driesbabe

I would like to know one thing tough.

WHY ARE PEOPLE SCARED TO TURN NEEDLES ON A GAS ENGINE????

what are they scared of? I have run hundreds of gas engines in the past years, none of witch have ever bitten me.
When I get to the field these same people are tuning there glow engines until the needle has done more revolutions than the engine.

I don't get it

willig10

That is the big question. It might boil down to a mindset that they dont tune their weedeaters. So they in turn think they dont need to tune their engines. I wish I knew.

Glenn

pe reivers

Yes, MVVS sets the needles, albeit quite rich, and even advises not to change them during running in. They had too many cases where engines were returned with messed up needle settings that ran perfectly well on the turn of a screw driver.
Every club should at least have an engine guru that knows how to set needles. Even then, some are extremely hardheaded and won't allow their minds to be intruded by newfangled ideas.

aussiesteve

Now you did it again
Some local "Gurus" are not necessarily knowledgeable. They are just listened to.

A couple of weeks ago, at an IMAC comp here, a very accomplished flier was "assisting" one of my "Factory pilots" to tune his new engine.

Unfortunatley I was not there so I heard about this after the event. What I was told (by more than one person who was there on the day) was this:

My factory flier has a reasonably new engine in his plane - it is a JC engine (Area 102). It has about a gallon or so through it. The engine was burbling at the mid range so the "Accomplished flyer (aka local guru)" "Assisted" with the "tuning". I was told that the more they messed with the needles, the worse the problem got But instead of going back to the beginning (Yes - the factory flyer DOES know the original settings to start from), they continued to make the problem worse. The "accomplished" flyer then proceeded to bag MY engine brand based on what he had been "achieving" with a completely different brand of engine on that day !!!

Now this accomplished flyer is a "local Guru" in most peoples eyes here (including mine when it comes to precision flying) because he is most definitely proven to be a good flyer. However Based on his performance that day? - he is DEFINITLEY NOT an "engine guru".

But people were still listening to his very misguided opinions.

Sometimes, the local Guru is not what he is made out to be. Very often they are just a good flyer but not necessarily knowledeable on all things to do with the planes.
If adjustments continue to make the problem worse, then they are usually headed in the wrong direction.

pe reivers

Yes I did it again, and probably will do it again in the near future Steve, and of course you are right. My experience is along these lines as well. But still, these guyse have earned themselves some reputation and respect. They are the guys that need to be educated. Knowing this, it reflects the problems that lesser guys have tuning gas engines, and the delicate balance between prop, muffler and needles. Even Tony Clark, considered by many as the super-guru per se, not to use THE three letter word, advises to have the needles set by him and forget them. We know, that a running engine changes it's fuel requirements as they run in. They change requirements as well if you fit a different prop or muffler. Weather or altitude changes. Yet he has many followers, and I had a hard time in the club I fly in to convince the pilots and allow me to fine tune engines that came from him.
I hope the good man reads this.

greengoose

To HECK with gas this gas that, needles this, needles that, factory this, factory that, Guys this is why they make electric weed trimmers and electric airplanes. All you electric guys watch out for those shorts as things can get pretty hot and dangerous...

spaceworm

Electric airplane tuning tip:

Smoke is energy! When all the smoke escapes out of your electric motor, batteries, servos, ESC, etc, then all the energy is used up and the device stops working.

Old Tesla proverb

pe reivers

How long could you run a 12kW motor? (250A @ 48V) Gas engines are here to stay.

Bonified Wingnut

Pat, I agree with you 100% and this goes for the 2 strokes I use at home such as line trimmers and chainsaws. Now that they have taken the slot out of the carb needles it is really a pain.-BW