compute42

My Feedback: (15)

Hey everyone, thanks for all the great posts on here, really helped me get my plane right the first time!
I fired up my engine this afternoon, I got a used one off of ebay and wanted to make sure it was running right before it came time to fly it... Anyhow, it's a YS45, and wow I was really impressed on how hard this engine pulled on the airframe of my LT-40. Took a bunch of flips the first start, but after that it starts 2-3 flips now.
My question is this... I went to the YS site, and it said a normal needle valve setting is 2-2 1/2 turns for the YS45. I had mine originally set at 2 1/2 turns but it kept dieing when I gave it some throttle past idle, Finally its around 1 to 1 1/2 turns where it seems to run the best, and there's still a little bit of blue smoke coming out still...
What I'd like to know, is how do I know I'm not running it too lean? by ear? what do I look for? do I want some sputtering at idle (cause it was purring like a kitten without any hickups and roared nice with some gas). Should I invest in a tach? is there some way to tell by ear or things I should look for ? I'm guessing that I'll open the throttle wide and lean it out to where it's at peak (by ear), and then richen it a bit?
I really got a good deal on this YS45 and I have a feeling its gonna be quite a good powerfull engine, and don't wanna blow it up just yet. Tach's arn't too expensive so if thats the way to go I have no problems buying a cheap tach....

Rain rain go away! gonna rain another week here in NY!!!! I wanna actually fly this thing.

Thanks!
~Andrew Dawson

DBCherry

My Feedback: (4)

Hey, this is great! Someone that's been paying attention to advice! [X(] [8D]

They've been tuning engines since before tachs were around, so yes, someone devised a couple of real clever ways to determine the best needle setting.

Here's my favorite:
Start your engine again, and since it sounds like it's set close to right, give it full throttle and raise the nose of the plane to at least 45 degrees. You should hear the rpm's increase. If they don't increase, or the engine sags or quits, then you're already too lean.

If you Do hear an increase in rpm's, you can lean it a bit more and try again. When you reach the point where the rise in rpm's is small, then back off about a 1/4 turn. That setting will ensure that the engine is lean enough to run well, but rich enough to handle the way it leans out a bit in the air as it unloads, and leans a bit more as the tank gets low.

The second method is to get to full throttle and "pinch" the fuel line just before it enters the carb. You should get similar results to the method above. I prefer the above because I've found it a bit more accurate.

If the engine was stumbling at the transition between idle and quick full throttle, then the low end (if two needle carb) would be a bit rich. If it just died, the low end would be a bit lean. (Same is true of the air bleed carbs, except reich and lean adjustments are backwards because you're adjusting air instead of fuel. )

Welcome to RCU and Good Luck with that maiden flight.
Dennis-

RCaillouet3

Simple answer, yes buy a tach!!!! This is one of the best tools EVERY RC pilot should have!!!

I am not to familiar with the YS engines, sorry. But if it is a normal 2 stroke, judging by ear can be done to some extent, but there is ALWAYS the risk of setting it to lean. 4 stroke engines on the other hand can be almost impossible to judge by ear.

2 stroke setting by ear is to run the engine to full throttle. SLOWLY lean out the high speed needle until you can no longer get the engine to run faster. Then RICHEN the engine until it starts to run with a quite rough setting. Then lean it back out just to the point where the engine regains a little higher pitch and the running gets smooth. Then pitch the airplane to a 45 degree nose high attitude and if the engine gains a lot of rpm by sound, richen the needle one click at a time until the rpm stays close to the level attitude. you may only need about 1-3 clicks of richening, but remember that you could be gettintg to close to running it to rich again with the more you go. Also, the engine should gain a slight amount of rpm when pitched up due to engine leaning out slightly; you are just merely trying to keep it from running to lean.

The problem with this is that you have NO idea how close to peak this setting is without a tach!

THE SAFEST WAY TO SET AN ENGINES HIGH SPEED NEEDLE IS TO USE A TACHOMETER!!! With a tach, you can get precise measurments on what your engine is doing! Without a tach, it is just a guessing game.

I always have a tach with me when instructing, and advise all of my students that purchasing one should be done as well. When I am at the field, my tach is avialable to anyone wanting to use it! With today's airplane costs, I would rather let someone borrow and use my tach to set their engine properly, than to have them do something that may ruin their engine and take them out of the hobby!

DBChery has given you some good advise as well!! I just like my engines to run more rich than to risk a too lean run.

Just my thoughts,

Reg

CheezeyPoof

I guess I'll be the bubble buster. IN my opinion and I have been around alot of YS engines but I won't own one. There is no dispute on the power they put out but every YS I have seen first hand are just plain finicky and a pain. That pump and diaphram can be a nightmare. They either run great or not but that just my opinion.

compute42

My Feedback: (15)

I must have gotten one of the good YS's then ... cause it runs really well (so far on the ground we'll see in the air) I just had to presurize the system by blowing air into the fuel tank with my fuel bulb, and droping some fuel in the carb, and it sputters right to life 2-3 flips. I think i'll buy a tachometer, Lucked out so far and don't need a electric starter for this engine.... I supose I could get a tach I have a 11x5 prop on it, I know I could prop it higher, but it's just an LT-40 and probly overpowered as it is... This engine looks like its about 5-10 years old, and at least externally hasn't been cared for that well, but it starts so easily, and if runs this well all the time I'll be very happy. (have just one tank through it so far)

compute42

My Feedback: (15)

One other quick question I'm using wildcat %10 nitro fuel.... thats the highest nitro my LHS had besides 30% heli fuel (I definatly don't need the power) Anyhow I told the guy at my LHS that I had a YS45 and was wondering about the 20/20 fuel I have been hearing about, he said the 2-stroke YS should be fine on this combo, and the 20/20 really only applies to their 4-strokes.... Anyhow, should I be getting a higer nitro? like 15% or the 20/20 YS stuff?

photoniq

I use the same technique on my 2 stroke os 46 as one of the other guys recommended.

To set the low end I quickly throttle up. If the engine dies the low end is too lean so richen it up. If the engine seems to be 'catching' or hesitating before getting to high revs then it is too rich so you can lean it out a little. The revs should go up quickly and smoothly.

I know I am running too lean when I go full throttle, lift my nose so that it is pointing straight up and the engine dies. I richen the high end needle until this behaviour stops happening and I maintain steady revs

Ok take everything I wrote with a pinch of salt because I am a relative beginner! Hope it helps,

P.

MinnFlyer

My Feedback: (4)

I prefer 15% in my 4-strokes. My fuel of choice is Cool Power. My YS 91AC loves it. So do ALL of my engines. I know I can run less nitro in my 2 strokes, but I like the fact that I can run one fuel in everything.

Montague

I run 15% Omega in all my engines, 2- and 4-stroke, for the same reason Minn said, it's just easier that way. (while I've heard that caster in 4-strokes can gum things up, I've never had that problem, so I keep doing it).

As for a tach, I have one, but rarely use it to set my engine mixture, espeically not on 2-strokes, and usually even not on the 4-strokes. I do either a pinch test or a lift test and listen for RPM changes. Even on the 4-strokes, you can hear the rpm change. It's not as obvious, but it's there. Part of the reason I don't use it is that unless you get a really good tach, the readings can vary a little, and some tachs don't settle down to a "rock solid" number very quickly. So you spend a lot of time waiting for the tach to settle on a number between each adjustment. I find it faster and easier to just use my ears. (of course, if you are the type that has a hard time waiting for the engine to react to a needle change (since it's not instant, esp on remote needles), the tach might help you remember to make your changes slowly and let things catch up to your changes. YMMV).

Also, most 4-strokes have very definate ways of telling you when they are too lean. Usually you get a knocking/pinging sound first, then you get the prop leaving the airplane . (no, I don't set my 4strokes by listening for the knocking and backing up from there, but I know that if I hear any kind of knocking to throttle back and fix it. Espeically when you have an engine that is going lean in the air.)

(mostly I use the tach to determine how well my engine is running, which engine is running stronger, and evaluate props, plugs, etc. Since I fly combat competitions, it's a useful tool. Espeically since one class of combat has an RPM limit in the rules)

phread59

I use my ears on all my engines. 2 and 4 stroke alike. I have no problems. I use all of the above mentioned methods. I do have a tach. I don't even know if it works. Never turned it on.

YS engines have a lot of power. Way more than you need on a Lt-40. But they are very good engines. Should last a long time. I run 10% nito in all my engines. I also use a synthetic/castor blend. i would never use fuel that did not have castor in it. It is a safty feature against lean runs that I cannot do without. Besides I LLOOOOVE the smell of properly cumbusted castor oil. Befor anyone says it yes I am a lot warped. Good luck with your YS and enjoy it.

Mark Shuman

dreadnaut

My Feedback: (5)

I have seen a lot of guys have problems with Y.S. I have not. I've had two so far.

The problem I see guys having is with setting the pressure regulator. The older Y.S. do not have two needle carbs. The low speed mixture is set with the pressure regulator. Y.S. says the this regulator is set at the factory and needs no adjustment. I found this to be true on my first Y.S., a .61 two stroke. I did have to adjust the regulator on my .91 4S.

The problems I have seen other guys have come from giving that regulator screw a full turn on their first try. It is very sensitive and if you turn it more that +/- 10 degrees, you have gone to far.

wrongwaywayne

I use a tach. I use the pinch the fuel line technique for both the high end and low end adjustments. It should rise 300 or so rpm when you gently pinch the line and then it will die (let go before it quits). You now have a properly adjusted engine hopefully for the rest of the day. This technique only works on the air bleed type carbs. The two screws work in opposit directions to one another.