No, I'm not an MD, but if you can tune a 2-stroke by ear, but not a 4-stroke, maybe you need to get your hearing checked by one?

Well Minn, I have a YS 1.20NC that will kick your mule if you try to tune it by ear. You just can't hear a change?? Not only can't you hear the change but the high end needle can be twisted a lot before you hear the drop. Why is this?? I don't have a clue. It's the only engine I have that is like that. Same thing with the low end but the old NCs used the pressure screw to adjust the low end, no low end needle on this one. All my other four strokes are easy to get the tune by ear or at least close. I still use my tach a lot when setting up a new engine and testing props. BACK to the question. About the only reason for using a four stroke is the noise and they have a smoother power band through all the RPM range and swing a bigger prop because of the torque. To maintain mine I just check the valves once a year and adjust if needed. All but one of my four strokes is a pumper of one type or another. With a pumper you can get away with installing your fuel tank any place you want in the plane. There are a lot of other little reasons for a four stroke but for the most part it's the cool factor.

I'll ask next time I'm in.

You guys make me laugh. How many of us love 4-strokes because they don't make the same sounds that two-strokes do? Quite a few of us, I'd imagine. Part of that is that the pitch changes aren't nearly as perceptible. Again, if you say you can hear the difference, that's really great for you. I'm proud of you. You deserve a gold star. Most of us, however, can't do that. For whatever reason you have difficulty accepting that. I'm not sure why.

If you can pick out exactly when a 4-stroke is peaked, that's great. If your ears will tell you when it's richened 300-500rpm, that's great, too. My ears don't work that way, so I use a simple, inexpensive tool.

Well, here's what I can tell you... I fly all over the country and I have never seen anyone tune an engine using a tach. So I would have to believe that MOST people do not use one.

Sure, there may be a few people here and there that do, but I've just never seen it done.

Really? So I suppose all of the discussion about it here over the years is just... imaginary. I need my ears checked, you need your eyes checked... aren't we a pair?

I think it would be a good topic in the engines forum - see how many people use a tach compared to their ears.

I'll be gland when the snow is gone and you guys can do some flying and improve your atitude a bit. I think cabin fever is setting in real bad

most of the guys who tune there 2strokes at our club use the pinch test to tune not by ear, this same debate was pummeled to death a couple of months ago and its now resurfaced again, with the same arguements against a tach.no real reason not to use one just "you don't need that kid" and some chest pounding about how they can do it without a particular tool, a bit goofy really[sm=spinnyeyes.gif].

I use a tach on my 4st engines which are the majority of the type I happen to have, all the guys at our field who have used 4st engines recomended using it and its a handy tool it really eleminates the guess work out of tuning your engines, something I do every flying session( adjust the high speed needle) by peaking the RPM and backing it off a few hundred so when the prop unloads it doesn't overheat the engine.

I pile that sort of advice into the same junk bin as the,"you don't need that engine manual just do it my way and you will be fine son" mentality,I call it poor .

for a beginner just starting out get a tach. use it familiarize your self with the tuning and running procedures, learn the engine inside and out and if you don't need it later pass it on to the next guy/girl who is just starting to learn the process of tuning there engines.

4strokes are not cheap, and a extra 15$ is worth it to me, and the planes I happen to fly with them, there not cheap as well .

valve adjustment kits don't come with OS engines now, there 12$mine sits in the corner 11 1/2 months a year, I get more use from the tach for sure.

I have checked the valves on my newer OS 91's and they have all held there adjustments even after break in runs, just like GB stated once a year is about all they need just to be sure.

4st burn less fuel and are cleaner,alot less slime and the small amount of oil is burned more thoroughly than on a 2st, I like that as well

matter of fact I am going over the fleet now, doing my pre season clean up, valve checks, and EZ fueler maint. checks for flying season since we just got a new field
the only ones that needed to be adjusted were a couple of the engines I got off ebay after adjusting they ran great,(my gain).

I always use a tack on my 4-strokes.

Once I hit a certain rpm I take my transmitter and shift from low to high rates.

Spot on Campgems - let's now all move onto something more productive.

The attitudes being expressed in this thread are hardly conducive to fostering goodwill & encouraging beginners to stay involved in this wonderful hobby / sport / past time [8D]

I think the learning curve for the four strokes is a little bit different than the two strokes. I tended to go too lean on the top end when learning the four stroke. When I let that sink into my thick noggin, tuning became a breeze. The four stokes are fun. Good luck!

I like them all if they say ys . There is only one kind of good model engine the one that runs. I LOVE ENGINES WITH PROBLEMS . It dont matter if there four strokes or two and gas .I like buying them when no one know how to run them. A os four stroke is good choice and yes you need a tach for tuning. I WORST THING TO DO IS FLOAT A VAVLE DUE TO IMPROPER TUNING! And to small of a prop! a os 120 will swing a 15-8 ,15-10 ,16-8. They are a fine running engine.

I can't believe there are so many people out there whose hearing is that bad

You could, of course, just accept that there are many of us who can't do what you say you can do, Mike. What is really so hard about that? I'm truly at a loss for your inability or unwillingness to understand that. Which of the two is it?

These threads get pretty stupid sometimes, with people taking their arguments to the extremes simply because they can't hear what others are saying. My ears can't detect small changes in the speed of a four-stroke. They can with a two-stroke. Can you hear me when I say that? Can you listen to me, rather than attempting to tell me that I'm wrong about my own senses? There's no need to take this argument to the point of absurdity. Pride shouldn't get in the way of hearing what another is saying.

What bothers me is not that some people can't hear the difference. Ok, I'll accept the fact that some people need a tachometer to tune their 4-strokes.

What bothers me is when someone tells someone else who may be a little gun-shy about buying their first 4-stroke that they MUST buy a $30 piece of equipment to go with it or they won't be able to tune it - even though everyone I know does not need one.

Now you are the first one to say that we are not all alike, yet you jump on me when I tell these same people that they do NOT need to spend that extra money, nor do they need to learn a new technique to tune their engine. But you stick to your guns defending your position.

How about this:

Tune your 4-stroke the same way you would tune a 2-stroke. If you find you can't hear the difference in RPM (which some people can't) you may want to consider getting a tachometer to help you out.

Amen brother Mike. I have several 4 strokes from 52's to 180's and I don't use a tach. Yet they all run good.

I think that's a much more reasonable position to take than what you had been saying. It's incomplete, but it is much more reasonable.

That advice you just gave should really include some caveats. Four-strokes are different from two-strokes. Giving people the impression that they aren't is a mistake. If a person leans a two-stroke too much, it becomes pretty obvious from the sound of the engine slowing. If a person leans a four-stroke too much, it becomes pretty obvious from the prop flying off... I made that particular mistake this fall myself, and I'm certainly experienced enough to know better. It's irresponsible not to make people aware of certain possibilities before they're in a situation where the possibility can come about.

Some four-strokes have very specific break-in instructions. My TT54 was pretty explicit about not exceeding 5,000rpm for the first few minutes of its life. Get close to it, but don't exceed it. Now, just between you and me, I'm not able to count blades passing by one side of the engine at 10,000 per minute. That's just one of the limitations I have have. Others may be in a similar situation, if not blessed with that particular ability. It's easy to say "close enough is ok," but some people just don't like that. There are more than a few Type As in our hobby.

I don't think of a tach as being much different than a starter. Nobody needs a starter. Yet most of us recommend them, don't we? We don't get up in arms about someone recommending them, either. Somehow this is different, for some reason.

Perhaps it's safety? Starters make the hobby safer. That's a good reason for using one. Well, it may not be a bad reason for using a tach, too. Ever worn hearing protection while starting an engine? I don't, but that's because I'm stupid. Having seen my father begin to lose his hearing, I'll see if I can remember to change that this season. Can you hear a pitch change of a four-stroke going from 9,700rpm down to 9,500rpm while wearing hearing protection? I don't know. How much does that dull the senses, and how far lean will you be by the time you notice? I can't say, but someone who can hear the difference and happens to have a tach might be able to tell us. I'd be interested in knowing.

It's one thing to encourage people to try a four-stroke, and another to perhaps lead them down a garden path. We're all adults here. Give people all of the information, and let them make informed choices for themselves. Words such as "nobody", "everyone", and "anyone" don't really encourage reasonable positions. And since when does a tach have to cost $30? Mine cost $20, and I'm sure they're still available for that. Let's not inflate numbers when we don't have to.

Most people here who are considering a four-stroke aren't completely new to the hobby. Most have probably seen and heard one, which might be why they're interested. If they pay attention at the field, they'll know whether they can hear a four-stroke peak by ear. Let them come to that themselves, rather than taking an extreme position simply because you see other people taking an extreme position. All people need is information.

i could spend countless hours rebuilding, but i choose to listen to the people at central hobbies .and they say a tach is real handy. but when you buy 200.00 motor it dont matter but my motors cost 350.00-750.00. i tend to listen to what they have to say. and i never bought a tach it is built in my radio but not all have this.

My $30 figure was from research. I found one tach for $20, one for $25, two for $28, and one for $46 Which gives an average of $29.40

Ok, I inflated it 60 cents, but don't forget about tax and/or shipping.

My point is, there are a lot of people out there who are afraid of buying their first 4-stroke because of all of the horror stories they hear about them being finiky, or difficult to tune or constantly in need of valve adjustments. If they knew how little difference there was between the two, they wouldn't hesitate to get one and they would be enjoying a whole new aspect to the sport.

Will it require learning a few things? Maybe, but nothing they can't learn in a few minutes. Certainly nothing worth not buying the engine over.

PS, before a 4-stroke throws a prop from being too lean, the RPM will drop substantially. If you can't hear that, buy a tach

I get it . But you won't need a tach anyway after the RPMs drop substantially!

NorfolkSouthern

Like Mike says, I see too much talk about how much harder a four stroke is to tune and maintain then a two stroke,BS!! Nothing yanks my chain more then seeing people that have heard or seen someone with a YS having a problem then posting how hard a YS engine is compared to other four strokes. BS, that's just stupid!! That one little extra screw is almost never touched. I only open my engines once a year to check the valves, not adjust them. Tachs, I went for a lot of years with running four strokes without ever having one. Then I tried some cheap tachs because I work and tune so many four strokes and wanted to get things set dead on. I couldn't find a good cheap tach so I spent the money and now have the high end unit. I use it but not that often on my own engines. I did when they were new or just got rebuilt but I know my own engines very well and don't need my Tach all that often. I use it when I'm working on someone elses engine though. I'm only flying one plane these days with a two stroke engine, I really like this two stroke but I really really like all of my four strokes. Anyone thinking of buying a four stroke for the first time, go for it!! There is nothing very different or hard about them. If you want the power give a YS some thought. A four stroke in a GEE BEE??? Cool!!! If it was mine it would be a YS though!! I also use a TNC tach. Way Cool!!!![8D]

Easy Brothers,


The OP just asked a question, in
which he has an answer for.

Get the 4 S


Bob

Go ahead and get the four stroke and enjoy. Just pretend it is a two stroke at first and you will get used to it in no time.

The OS 120 four stroke is a conservative runner and you will just love it.

One guy told me to tune my engines with my "ear", but after losing one I found it much safer and easier if I use my fingers!

Expect your 4-stroke to have the letters O.S. on it.