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RE: First 4-stroke engine. Help?
Ihave seen trouble with the Magnum 4 strokes leaking valve seats. Mine was sent back and the head was replaced under warranty and now it works fine and holds good compression.
Had to buy an OS 70 four stroke to "see the light" so to speak. |
RE: First 4-stroke engine. Help?
ORIGINAL: MinnFlyer Well, I dare say that I have broken in two OS 70s, four OS 91s, two Saito 82s, a Saito 100 and a Saito 125 all in the last two years (And just last night I found my tach which has been missing for three years :D ) The only reason I even OWN a tach is because a few years ago I was reviewing an engine and wanted to show a picture of the digital RPM readout. Here's the deal... You start the engine and bring it to full-bore. Assuming the mixture is rich, you start to lean it out. You will hear the RPM increase. At a certain point, you will find about 5 or 6 clicks where there is little or no increase and then you will hear the RPM begin to fade - this will be followed very closely by the engine running very poorly and if you don't bring the needle back, it will quit. Ok, so when you get to the point where it starts to fade (let's call it click 7), bring it back to click 1 or 2. Now, nose the airplane up. The RPM should stay the same or SLIGHTY increase. If you hear a drop in RPM, you need to richen the mixture up another click or two. This is not rocket science. Now, here is the problem with a beginner using a tach: ORIGINAL: Campy USE A TACH !!! In order to set up a 4 stroke you will need a tach. Your MAX rpms are going to be ABOUT 10,500 (depending on the prop and nitro content). I have personally had someone ask me to help him get his engine running right. The engine was toast because he was told he should get 10,000rpm and he was only getting 9800 on his tach, so he kept trying to lean the engine out to get that last 200rpm. Tachs do not take altitude, humidity, prop size, prop length, fuel brand, nitro content, or the condition of the fuel into consideration. A tach tells you numbers. Numbers don't mean anything. You might get 9800rpm today, and have a warm front move in tomorrow and you only get 9700rpm. No matter what you do, your engine will not put out 9800rpm today. I can see the tach junkies flipping out! Now, someone please explain why you can tune a 2-stroke by ear, but you MUST use a tach for a 4-stroke when the procedure is identical? |
RE: First 4-stroke engine. Help?
The Tach is a crutch? Thats a crock! The tach, like any tool, has to be used properly and its ability to provide useful information must be understood to be of value. I guess full size aircraft and race cars use them as a crutch also. The Tach, if used by a knowledgeable person, is a valuable tool. It does nothing by its self. Only the operator can interpret what it says and the value of that information. If you don't know how to use it then it's not even a crutch it's more of a rock.
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RE: First 4-stroke engine. Help?
ORIGINAL: oldvet70 The Tach is a crutch? Thats a crock! The tach, like any tool, has to be used properly and its ability to provide useful information must be understood to be of value. I guess full size aircraft and race cars use them as a crutch also. The Tach, if used by a knowledgeable person, is a valuable tool. It does nothing by its self. Only the operator can interpret what it says and the value of that information. If you don't know how to use it then it's not even a crutch it's more of a rock. Sorry i couldn't help it. LOL |
RE: First 4-stroke engine. Help?
interesting veeery interesting!
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RE: First 4-stroke engine. Help?
ORIGINAL: rgm762 thanks Brad, I'm having problem with 2 magnums, a 52 and a 70, is it also true that mgnums don't transition as good as other 4 strokes? Brad |
RE: First 4-stroke engine. Help?
1 Attachment(s)
I have used all tips mentioned above, and they all work. Main thing I have come to notice is don't expect a lot till you get a gallon or 2 thru any four strokes. I do recommend you run a 10% nitro ,castor/syn, blend with at lest 18% oil . Break in as Magnum manual recommends .
ASP/Magnum weak spot is a sloppy fitting HS needle , I used largefuel tubing on a coupleand it has do the trick nicely. |
RE: First 4-stroke engine. Help?
I don't think a tach is a crock or a crutch. And if someone chooses to use one, have a ball. I just get bent out of shape when people tell a rookie that they MUST use one.
To me, it's like telling someone who is just starting out that they MUST have a power panel and an electric starter or they'll never get their engine running. |
RE: First 4-stroke engine. Help?
HI do set the high end first pinch method is good thereto set the low endcome up a few hundred rpms from idle ( 500-1000 )-turn the low end in until the engine starts to run a bit roughback out the needle valve until the engine noticable starts to run very smooth-the low end is SETnow set your idle speed based on the wind conditionsidle speed should fly the plane on to the runway- before a days flying i always check my high end RPM on a tachto be sure i have not developed an air leak of some kind and all is as it should be-a loose headhole in the fuel line-carb base loose fuel tank leak will cause an air leakan air leak if not detected will lean you out-cause excessive heat and render you dead stik-and burn out the glo plugdead stick is alway a safety hazard-and an unpleasent situation to have to deal withso be sure to have your engine is set up before take off -any sudden increase in your RPMSor your needle valve needing a new adjustmentwhen it always ran at a certain place -is a sign air is getting into your engine-should be investigated and corrected before taking to the air again based on 25 years of handling glo engines-ENJOY REGARDS TONY " the omega man " think pink
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RE: First 4-stroke engine. Help?
Peter Chinn, Clarence Lee, Dave Gierke, etc. are a bunch of goofballs and don't know anything about model airplane engines, how to tune, run, and maintain them. When they recommend the use of a tach among other tools, don't listen to them as they don't know what they are talking about.
Campy, you read the OP's original post, analyzed his experience with 4C RC glow engines, and strongly recommended the use of a tach (you didn't say he must use one). I would bet the farm that if the OP had written in to MAN or directly to him, Clarence Lee would have given the same advice. The OP has heard feedback from many here and it is his decision as to how he proceeds. Lars PS: I find it hard to believe that the OP has to pay $140 for a tach. He could order one direct from Tower that would cost around $20. Shipping to Norway costs around $12, so the way I see it he could have a tool for his flightline that would run him $$35 - $40. |
RE: First 4-stroke engine. Help?
Tony, the spacebar and punctuation are your friends. It's ok to use them! (good advice though)
I have had one four stroke and tuned it without a tach, but I had some confusion in the process and wasted some time. Mine had a broad peak (which is typical, I'm told) that sounded the same throughout its range to me. It didn't peak and then drop immediately like a 2 stroke does. A tach would have told me exactly where the peak was, making tuning easier. It sounds like a more experienced tuner can do it by ear, but the tool is helpful to make those exact adjustments. |
RE: First 4-stroke engine. Help?
Morten,
You probably have gotten more advice than you wanted or needed. It just depends on what kind of pilot you want to be. There are the old school guys that get a new engine, through away the box and instructions, screw on a prop, bolt it to a plane, tune it up by ear and go fly. There are guys that break the engine in on a test stand, perfectly balance a prop, count how many tank fulls that have been ran through the engine, tune it up with a tach, and can give you every detail and number you could think of. Both are right and both have a great time flying their planes. So, the best advice is to be the kind of pilot you want to be. Again, you have gotten all kinds of great advice from many perspectives. If you want to be the technical guy, old school guy or somewhere in between, just be the one that works for you and have fun! Brad |
RE: First 4-stroke engine. Help?
ORIGINAL: scflyboy Morten, You probably have gotten more advice than you wanted or needed. It just depends on what kind of pilot you want to be. There are the old school guys that get a new engine, through away the box and instructions, screw on a prop, bolt it to a plane, tune it up by ear and go fly. There are guys that break the engine in on a test stand, perfectly balance a prop, count how many tank fulls that have been ran through the engine, tune it up with a tach, and can give you every detail and number you could think of. Both are right and both have a great time flying their planes. So, the best advice is to be the kind of pilot you want to be. Again, you have gotten all kinds of great advice from many perspectives. If you want to be the technical guy or old school guy, just be the one that works for you and enjoy this great hobby! Brad |
RE: First 4-stroke engine. Help?
ORIGINAL: hiTmanhiT Hello! Just got my first four stroke engine. A ASP .91. I am going to use it in my U-can-do 46. I have never set up a four-stroke before, only two-strokes. So I was wondering if someone could help me out a little bit here, since the manual didn't help me out much(Chinese quality!). Do you have any guides or something? Or maybe you could explain a little bit for me? Thank you very much, Morten http://www.hobbycity.com/hobbycity/s...ASP-FS91AR.jpg this was a significant weight loss and the plane flew better than ever. negative side of all this is the goo, I have had enough, no more glow , from now on its gas or lipo. break it in slow and use your tach to set needle and it should run like a champ. |
RE: First 4-stroke engine. Help?
ORIGINAL: scflyboy So, the best advice is to be the kind of pilot you want to be. ~ If you want to be the technical guy, old school guy or somewhere in between, just be the one that works for you and have fun! Brad |
RE: First 4-stroke engine. Help?
I always adjust the low end so that I get a smooth transition from idle to full throttle.....huh.........as far as glow plugs go. i use OS type F in everything. Seems to be the best all around plug in my experience. Pricey, yes, but worth it.
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RE: First 4-stroke engine. Help?
ORIGINAL: airboss/oc negative side of all this is the goo, I have had enough, no more glow , from now on its gas or lipo. |
RE: First 4-stroke engine. Help?
ORIGINAL: ChuckW ORIGINAL: airboss/oc negative side of all this is the goo, I have had enough, no more glow , from now on its gas or lipo. THere is a quite noticable difference in the amount of spray back from the carb. That engine is cowled, and there is almost no oil in the cowl after the stack was added. Some Saitos came with stacks and some didn't, but I'm sure you can get a stack to fit your carb, I know I just put one on a Saito 91 I rebuilt that didn't have a stack. The O.S/Magnum cabs are easy to add a stack to, and on another thread, there were some nice ones made from soft copper tubing. It is worth looking into. Don |
RE: First 4-stroke engine. Help?
The Saitos I had always spit like crazy out the crankcase vent line. The OS .91 and the Alpha series don't vent the crankcase in the same way so they aren't near as oily. There seems to be a lot less out the exhaust too. That could just be perception though. The 1.10 alpha carb doesn't appear to be the same as the .91 surpass-2 but I could be wrong about that. I haven't examined it too closely or looked at the part numbers.
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RE: First 4-stroke engine. Help?
I try to vent the case outside the cowl. Iusually use a piece of brass tube on the end to get the spray down into the air flow a bit better. Doesn't fix everything, but helps a lot.
I'm not sure about the 91vs 112A carb body. They are both 60 series carbs, but the bodys do have a different PNs. My guess is that they are basicly the same, Maybe a little larger throat on 110a to allow for the extra 0.20cuin desplacement. The barrels were changed between the 52 and 56a, but the carb body was the same PN. There doesn't seem to be the same changes on the 110A engine, so I'm not sure if that stack would fit the 91 carb. Don |
RE: First 4-stroke engine. Help?
Since there are plenty of help in tuning the engine and it doesn't matter whether it's a 4 stroke or 2 stroke basically the same method applies. One thing I did not see mentioned though and think it's very important. When breaking in new engines do not vary their speed by using the throttle vary by altering needle setting from time to time. this permits engine to operate at varying speeds but with varying amounts of fuel and lubricant. Once several tanks have been run through it, 5-6 then put it in the air for further break in but use a fairly rich setting. Engines run quite differently in flight than on the bench. Actually there's no substitute for experience and this you will get in time. I think I finally got it now after 55 years of doing this Ha.
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RE: First 4-stroke engine. Help?
i bolt my engines on my plane and have at it, no breakin on the bench. what i do is keep the low end very rich and the high end rich, but lean enough where it will clear out.
then i fly it just above the point where the engine doesnt load up for a min or so, then lower the throttle and let it cool off/load up, then i advance to the point where it clears out and alternate till its time to land. i do that for a few tanks with a small prop for 2 strokes, and the regular prop for 4 strokes. so far i havnt had any problem doing that, and its more fun than watching a engine spin on a bench (which is still fun :D) the key is to understand the engine before it goes in the air. for example a th .46 is a very tight engine from the getgo, during the first few tanks the engine will not run under half throttle. i didnt know that when i first put it up but i realized it rather quick because i listen to the engine, you can tell it was dieing, so just up the throttle. i have the magnum .91 (same as asp), i think it will be way to heavy on that plane, the plane will not float around very well. if you can put the battery in the tail of the plane and the motor on the very back of the mount. and forget about useing a spinner, it will make it even more nose heavy. |
RE: First 4-stroke engine. Help?
Morten,
I have a Magnum 71 and I'd recomend that if this is in fact a ring'd engine you should try to run it on a test bench (or in my case a plank of wood with an an engine mount cut into it :eek:) first for about 30 minutes then transfer it into your plane. The only reason I recomend using a stand for break in is thet if the engine malfunctions there is only a small chance of it getting away from you and injuring some one (or you) in the process. Also if you can buy a tach, It will re pay itself in the long run. Hope I helped -Chris Larsen Member of The Livermore Flying Electrons |
RE: First 4-stroke engine. Help?
O.K., you guys seem to know how to get engines running well. I have two saito 82's. The first I have been running for two years on 30% heli fuel with a 14x4w prop; 3d stuff. Just bought a pattern plane, extra 300sp and a used saito 82. Could not get the second engine running right; kept getting detonation on acceleration and spinning off the prop no matter how rich I ran it. Finally sent it back to Horizion to have it checked out. Had bearings replaced and and some carb parts and glow plug replaced. Spun the prop off with 30% nitro on the first run. Have been running 15% ever since with no problems. I would like to run 30% due to the increased power. Is there a trick tuning with 30%? I can only find heli fuel with 30% nitro, I was told this just has more oil than 30% fuel for 4 stroke. Never been a problem before, any thoughts on this one? Once again, a Saito 82 running a APC 14X6 prop. Will turn 9300 or so at sea level with 15%. Thanks again for your thoughts.
Mark |
RE: First 4-stroke engine. Help?
I cannot comment on O.S engines as I don't use them, but anything with a castiron ring and a steel cylinder, I run several tanks thru on the engine stand. Such as ASP/ Magnums. Saito's I mount to the plane and run a tank thru then fly them rich for a gallon or so . They have a chrome cylinder and take for ever to break-in, so I generally break them in flying them.
A tach, does have it's place , I use one if there is a lot of other engines running around me and I can not quite hear what I'm doing . Especially if someone is running a 2 stroke , the higher rpm's really throw me off while trying to tune a 4 stroke. |
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