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Can YOU tune a 4 stroke by ear?

Old 07-16-2012, 04:07 PM
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bob8619
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Default RE: Can YOU tune a 4 stroke by ear?

I am still concerned about how much smoke I have coming out of the exhaust. I lean it out til its really ripping then richen it quarter turn +/- and its so smokey. How smokey would you say is too smokey?
Old 07-16-2012, 04:20 PM
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GaryHarris
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Default RE: Can YOU tune a 4 stroke by ear?

That depends on the make of the engine. Saito's are very sloppy and Magnums are much cleaner and I can't help with OS since I only had one.
Old 07-16-2012, 04:25 PM
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Default RE: Can YOU tune a 4 stroke by ear?

Alright mines a Saito, my first, so perhaps what I feel is too rich based on smoke is just normal, even at a lean setting its still puttin out quite a bit of smoke.
Old 07-16-2012, 04:33 PM
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Default RE: Can YOU tune a 4 stroke by ear?


ORIGINAL: bob8619

Alright mines a Saito, my first, so perhaps what I feel is too rich based on smoke is just normal, even at a lean setting its still puttin out quite a bit of smoke.
bob8619, there is a super forum for Saito engines, Club Saito in RCUniverse that give tremendous help for Saito engines. But from my experience and what I read in the Club Saito forum, the exhaust will always be smokey, even when not tuned rich. So, don't go by exhaust smoke to tune a Saito. I use a tach for 4-strokes, and hearing for 2-strokes.
Old 07-16-2012, 05:37 PM
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Default RE: Can YOU tune a 4 stroke by ear?


ORIGINAL: AmishWarlord

OK Now I have a question.

Does the pinch test work on four strokes like it does in two strokes?

Yep, sure does. Imade a video of it with my iphone but dont have a clue how to post it. The Magnum pinch tests much easier than the OS does.

Kelly, Great post. Other than the low end adjustments, Im pretty much there, but wont fine tune the low end until after the 5th flight, engine is just broke in. Going to follow your tips to fine tune it, and my OS, which is too lean. Right now the Magnum I got it down to 2200 RPM at idle, and it will go lower, but dont want it too low, hate to have it dead stick on final. Definate rich on the low, but it revs up, no burble, no hesitation, but slow to rev, lots of smoke. It should be a sweet motor once fully broke in.

Old 07-16-2012, 05:48 PM
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Default RE: Can YOU tune a 4 stroke by ear?

you guys that suggest tune to max then drop XXX(X) rpm rich isnt good info. each engine is different, each airframe is different, different fuels and different tank instalations will cause different readings in the air. i only use a tach for testing props thats it. i never tune an engine by the tach then go fly. you most always will be lean inflight. fot the new guys at engine could use a tach to set max but the backing off part is hard to set a set value in a forum. get help at the field.

Pinch test on most four storkes dont work either because of the time it takes for the fuel to go thru the carb and to the engine. setting saitos you should turn the neele a couple of clicks either way then wait 3-5 seconds. it takes some time for it to catch up.
Old 07-16-2012, 07:57 PM
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Default RE: Can YOU tune a 4 stroke by ear?

Sure you can use a tach to set the engine rich enough to run right in the air. It's just a matter of technique. Here's my OCD way of doing it on an engine that's broken in well enough for fine tuning to be meaningful: First, I find what the max rpm is. That's where I want the engine to be in the worst case scenario, which would be on a straight up line with maybe 1/3 a tank of fuel. I then use the tach to go back 300 rpm rich, then test that upline tune. It's too dangerous to try and tach the plane while holding it vertical, so I listen for it to give me the slightest rpm increase (300 is about the smallest change my ears can detect) and then hold it in that position for 10 seconds. I never do up lines that long, but I know that if the engine does not lean out and change its sound or quit then I'm set rich enough. If that test fails, I go to 500 rpm rich and try again. When I'm happy with that, I fill the tank up and check how many rpms I'm off of peak on the test stand, and that becomes my perfect tune for that engine in that plane with that tank setup. For the low end I can be very accurate and actually a good bit faster about setting the idle and transition mix. I get the lowest idle that the engine will run reliably and tach it over about 30 seconds. I keep leaning the needle until it holds steady (always fluctuates a bit, but I'm looking for it to stay in the same range) then I drop it down a little lower. Not surprisingly, the lower I set the idle the more sensitive the engine is to having the LSN set right. Once I'm down to the idle setting where I'm only once click between loading and slowly dying and suddenly leaning out and dying, I go back up maybe 300 rpm and check the transition. 90% of the time it's dead on. With 4 strokes it's a little different on the low end as I simply tweak the needle for the highest reliable rpm at the idle setting then work down the same way. The high end is then double checked to make sure it's still at that baseline I established earlier, and I'm done.

Some will ask "Why go to the trouble?" My response would be that it doesn't actually take long to do assuming I start with an engine that's close to being right to begin with. It certainly takes less time than chasing a proper idle and waiting to see if the engine is going to load up instead of instantly seeing what it does. And it definitely takes less time and money than rebuilding an engine that was damaged in a lean run. Of course some will say to just run it "a little rich" and be done with it. I found in my testing that my version of what sounded "a little rich" was about 1000 rpm off peak. That's about one engine size, so my .46 was actually flying like a bushing .40. So I take the time to get my engines tuned perfectly so that I get the power out of them that I've paid for without going too far and damaging them.
Old 07-16-2012, 08:32 PM
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Default RE: Can YOU tune a 4 stroke by ear?

easy, its not a pylon race, tune it so its reliable and happy. I have a tach, cant remember the last time Ive used it though, its not needed.
Old 07-16-2012, 08:48 PM
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Default RE: Can YOU tune a 4 stroke by ear?


ORIGINAL: GaryHarris

I can tune a fish! [&:]
BS, everyone knows you can tune a Guitar but you can't Tunafish!!!!!!!!!!
I remember the LP but not the artist.
Old 07-16-2012, 08:59 PM
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ORIGINAL: koastrc

One of our members test his tach by pointing at a light bulb, light on. He says the tach reads the RPM of the generator at the power house and the power house RPM is constant. Perhaps that is true. What is true, this guy always seems to be correct in other areas. I have never owned one, but have used his.
What Jester said and it must be fluorescent, not just a light bulb. In camera shops they used to have a glass at the counter with a fluorescent light in it, that was used to test the light meter in a camera, the generator at the power house is a bit off but I like it!! Just because a tach reads the light correctly doesn't mean the tach will work correctly. Some of them can't see the prop under any light, I have a couple old ones that won't work no mater what you do but read the light perfectly.
The TNC will work from several feet back from the prop, it's one of the selling features and it is affected by light but so far it still reads the rpm no mater what or where. It's just more then most people require at $100.00 a pop.
Old 07-16-2012, 11:54 PM
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Default RE: Can YOU tune a 4 stroke by ear?

If your comfortable tuning by ear then by all means. If your not sure then get a tach that works. No need to spend big money. I use the Hobbico tach and they all work well at my field. On the other hand we have a few glo-bees and they all jump around.

One thing not mentioned is tune your saito with only 1/4 tank of fuel. I like to tune with the amount of fuel in my tank that I am landing with. That way you can get that extra 100 rpm's that some of us want. I richen my 2c by 200 rpm's and my saitos by 100 rpm's. By tuning with 1/4 tank you know that it will only get richer by adding fuel instead of guessing on how much you THINK it will lean when flying and compensating for it. I don't like guessing.

http://www3.towerhobbies.com/cgi-bin...&I=LXPT32&P=ML
Old 07-17-2012, 12:55 AM
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Default RE: Can YOU tune a 4 stroke by ear?

Gray Beard, that was one of REO Speedwagon's early albums
Old 07-17-2012, 08:14 AM
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Default RE: Can YOU tune a 4 stroke by ear?


ORIGINAL: bob8619

I am still concerned about how much smoke I have coming out of the exhaust. I lean it out til its really ripping then richen it quarter turn +/- and its so smokey. How smokey would you say is too smokey?
You tune the engine, not the smoke. Saitos do tend to run fat and will smoke more then an OS, not a big deal. If you worry about the smoke trail then change over to a full synthetic fuel. That will get rid of the smoke trail quite a bit.
I still fly with some guys that will tell me my engine is running lean because it has very little smoke trail. I was just testing a new fuel when Power Master was out of production. It only had 16% synthetic oil. The fellows decided I had the engine tuned properly the next flight because it was smoking again, I never touched the needles, I did add two ounces of Klotz oil blend in the fuel can. This was a YS engine and they tend to not have a big smoke trail when tuned correctly, the Klotz blend has 20% Castor oil in it, Castor oil smokes. Just tune the engine and forget the smoke trail, some engines and some fuels just tend to smoke more then others.
Old 07-17-2012, 09:42 AM
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Default RE: Can YOU tune a 4 stroke by ear?

Roger that. Smoke doesnt bother me just wanted to be sure it wasnt because it was too rich.
Old 07-17-2012, 02:55 PM
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ORIGINAL: bob8619

Roger that. Smoke doesnt bother me just wanted to be sure it wasnt because it was too rich.
It could be???????? An engine will tell you if it is too lean or too fat when you try to fly the plane. You can have an engine running what seems perfectly on the ground then lean out in the air or start bogging down from being too rich. Each engine is a world unto it's own.
Old 07-17-2012, 04:10 PM
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Default RE: Can YOU tune a 4 stroke by ear?

You can tune a piano, but you can't tune a fish. REO.
Old 07-17-2012, 07:52 PM
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Default RE: Can YOU tune a 4 stroke by ear?

Yep, a junkie told me that.
Old 07-17-2012, 09:26 PM
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Default RE: Can YOU tune a 4 stroke by ear?

ORIGINAL: Gray Beard

Yep, a junkie told me that.

On vinyl just for you old timer. I couldn't find it on 8 track.


It's time for me to fly. [&:]

http://www.youtube.com/watch?v=keQcg-r2YI8
Old 07-18-2012, 09:24 AM
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Default RE: Can YOU tune a 4 stroke by ear?


ORIGINAL: GaryHarris

ORIGINAL: Gray Beard

Yep, a junkie told me that.

On vinyl just for you old timer. I couldn't find it on 8 track.


It's time for me to fly. [&:]

http://www.youtube.com/watch?v=keQcg-r2YI8
You laugh but before I moved here to Vegas I had one huge sound system in my shop. My shop was our old Mobil home and 1000 sq. ft. it was a quad system with four matching book shelve speakers. Why they called them book shelve I will never know? I needed a dolly to move them around! Truth!! I had a super turn table too with adjustable tracking, really nice!!! I used to go into Merced to a thrift store and spend hours going through there record file, For $1.00 a piece it was a deal.
I gave the system away when I moved here, I have no place I could set it up that is big enough.
I have gone to the CES show a number of times and when you go in to listen to the 50K a piece speakers you are listening to Vinyl through an Analog sound system. It was discovered a long time ago Vinyl and Analog has a much better sound quality. In my house today I have surround sound, good but it is just lacking something?
Old 07-18-2012, 11:01 AM
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Default RE: Can YOU tune a 4 stroke by ear?


ORIGINAL: bob8619

Roger that. Smoke doesnt bother me just wanted to be sure it wasnt because it was too rich.
Saitos can run just fine with the needles set ridiculously rich. Test the engine as already noted, and if it is still too smokey, try a different fuel.

You may not be able to do anything about that though... My Saito's don't seem very smokey, but I've seen other people with VERY smokey Saitos... I wonder if it is due to a valve problem?

Old 07-18-2012, 11:15 AM
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Default RE: Can YOU tune a 4 stroke by ear?

My fuel was purchased in 2008, not sure if that plays into the smokeyness
Old 07-18-2012, 11:31 AM
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Default RE: Can YOU tune a 4 stroke by ear?


ORIGINAL: bob8619

My fuel was purchased in 2008, not sure if that plays into the smokeyness
As long as it was unopened and out of the sun, it shouldn't really matter...

Old 07-18-2012, 12:17 PM
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It had been opened but the caps been on, and in my flight box, in the dark.
Old 07-18-2012, 12:21 PM
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Default RE: Can YOU tune a 4 stroke by ear?


ORIGINAL: Gray Beard


ORIGINAL: GaryHarris

ORIGINAL: Gray Beard

Yep, a junkie told me that.

On vinyl just for you old timer. I couldn't find it on 8 track.


It's time for me to fly. [&:]

http://www.youtube.com/watch?v=keQcg-r2YI8
You laugh but before I moved here to Vegas I had one huge sound system in my shop. My shop was our old Mobil home and 1000 sq. ft. it was a quad system with four matching book shelve speakers. Why they called them book shelve I will never know? I needed a dolly to move them around! Truth!! I had a super turn table too with adjustable tracking, really nice!!! I used to go into Merced to a thrift store and spend hours going through there record file, For $1.00 a piece it was a deal.
I gave the system away when I moved here, I have no place I could set it up that is big enough.
I have gone to the CES show a number of times and when you go in to listen to the 50K a piece speakers you are listening to Vinyl through an Analog sound system. It was discovered a long time ago Vinyl and Analog has a much better sound quality. In my house today I have surround sound, good but it is just lacking something?
You can't beat analog brother. I just bought a new guitar amp and it has 9 vacuum tubes and no transistors. Old school/vintage is the new norm.

Bob, as opjose said, you should be fine.

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