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2 Stroke V. 4 Stroke

Old 08-16-2011, 07:23 AM
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Admiral052
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Default 2 Stroke V. 4 Stroke

I am looking for information on the major (and minor) differences between the two beside how they operate and how they sound. I know nothing about the 4 strokes.
I like the sound of the 4 stroke and I am wondering what kinds maintence is needed, precautions, starting, storing, things like that.
I currently have experience with the 2 stroke but I would like to use a 4 stroke on my next Glow plane and I am looking for info

Thanks RCU group
Old 08-16-2011, 07:38 AM
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RVator
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Default RE: 2 Stroke V. 4 Stroke

Four strokes are not hard to use. I use OS, Saito and YS. They seem to run the same glow plugs forever and I will adjust the valves about twice a year. I just like the way they run so much better than 2 strokes. The only downside for beginers is they can experience greater crash damage. Bent pushrod tubes,valve covers etc. You can usually dig a 2 stroke out of the dirt clean it up and mount it in a new plane. I even put a 56 saito on my son's Sig Kadet. It really flys it nice.
Old 08-16-2011, 07:47 AM
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Default RE: 2 Stroke V. 4 Stroke

Despite what you may hear or read there is no need to run 30% heli fuel or 4 stroke fuel....15% Omega works just fine
Old 08-16-2011, 08:13 AM
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Augie11
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Default RE: 2 Stroke V. 4 Stroke

Nothing like the sound of a good 4 stroke. Yes, they have more moving parts and are more expensive than 2 stokes. But once broken in and set up properly they just run forever.

I would suggest you stick with either OS or Saito for a first attempt. They are user friendly and very good quality. The lower priced engines just don't stand up as well in my opinion (and I've flown 4 strokes for 25 years). I know there are others who disagree. YS's are great, high performance, sophistcated machines and they have many fans. But these folks tend to have lots of experience with them.

As someone mentioned, 15% nitro is fine.
Use an OS #F glowplug regardless of what brand 4 stroke you decide on
Follow the manufacturer's instructions for break-in and tuning. They know a lot more than the folks using them.
Use (at least) the recommended oil content. I like to have some castor oil as part of my total oil (2 or 3%)
For your first engine, get a tach and use it until you get used to the sound. Stay in the recommended rpm range and prop size.
Check the valves after break-in and then maybe twice a year or if it ever seems to lose power.
Run the engine 'dry' after every flying session. Use after run oil if you live in a location with high humidity or use it for float flying.

I will now get a lot of feedback on the above, a lot of it negative. I don't care - the above works for me, and will work for you as well.
Old 08-16-2011, 08:25 AM
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Default RE: 2 Stroke V. 4 Stroke

I agree with most of what has already been said, however I must add that I have only adjusted valves once - ever (and I have been using 4-strokes almost exclusively for over 20 years)

I have also never used a tach to tune one. Can you tune a 2-stroke? Then you can tune a 4-stroke.

About the only difference is that a 4-stroke does NOT like to run lean, so if you're adjusting the needle, and you can hear that it is starting to get too lean, BACK OFF (or you might spit the prop off)

And ditto on sticking with OS and Saito your first time. Although both are more user friendly, OS seems easier to tune, need much less break-in time and spit MUCH less slime on your plane
Old 08-16-2011, 08:38 AM
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Default RE: 2 Stroke V. 4 Stroke


ORIGINAL: MinnFlyer

I agree with most of what has already been said, however I must add that I have only adjusted valves once - ever (and I have been using 4-strokes almost exclusively for over 20 years)

I have also never used a tach to tune one. Can you tune a 2-stroke? Then you can tune a 4-stroke.

About the only difference is that a 4-stroke does NOT like to run lean, so if you're adjusting the needle, and you can hear that it is starting to get too lean, BACK OFF (or you might spit the prop off)

And ditto on sticking with OS and Saito your first time. Although both are more user friendly, OS seems easier to tune, need much less break-in time and spit MUCH less slime on your plane
+1. I check the valves about once a year. If they need adjustment then I adjust, no big deal. I only adjust the high ends about twice a year, when the weather gets cold and when it gets hot. That's about four clicks defference from season to season. I run YS and OS. I'm not a big fan of Saito but that's just a choice thing. YS is not a good choice for a first timer but it is the best of the best. Just not a good one unless you understand them. The big difference between a two and four is the two will pull a lot more RPMs and the four will swing a bigger prop and put out more torque. They also have a better throttle responce through the mid range and you get better mileage. There really isn't any difference in how to tune one.
Old 08-16-2011, 08:40 AM
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Default RE: 2 Stroke V. 4 Stroke


ORIGINAL: jetmech05

Despite what you may hear or read there is no need to run 30% heli fuel or 4 stroke fuel....15% Omega works just fine
15% is overkill ( not that it hurts ) for the larger four strokers, unless you fly from higher altitudes.

All of mine fly just fine on 5%, though I typically use 10%.

-

BTW: I find the Saito's easier for a beginner than the OS in the four stroke arena.

Both are great engines, but the Saitos are REALLY tolerant of grossly rich settings and will run that way all day long.

Do the same with an OS and the engine will quit, usually in flight when you throttle down for a second or two....

Typically if you can get the Saito started, it will fly that way, though not at best tune and it will consume copious amounts of fuel until properly tuned.

I've also had fewer problems with the exhausts and mufflers coming loose for some reason, on the Saitos. The OS mufflers and exhaust headers require that I drill and tap a set screw more often than not. Dunno why.


Old 08-16-2011, 08:47 AM
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Desertlakesflying
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Default RE: 2 Stroke V. 4 Stroke

Use the pumped engines from OS and you don't need a muffler........lol
Old 08-16-2011, 08:52 AM
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Default RE: 2 Stroke V. 4 Stroke

I have had a Saito 65 for years. I have never adjusted the valves and can not remember the last time I even turned the needle valve or replaced the plug. It runs great and is strong.
Old 08-16-2011, 08:57 AM
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Default RE: 2 Stroke V. 4 Stroke


ORIGINAL: opjose


ORIGINAL: jetmech05

Despite what you may hear or read there is no need to run 30% heli fuel or 4 stroke fuel....15% Omega works just fine
15% is overkill ( not that it hurts ) for the larger four strokers, unless you fly from higher altitudes.

All of mine fly just fine on 5%, though I typically use 10%.

-

BTW: I find the Saito's easier for a beginner than the OS in the four stroke arena.

Both are great engines, but the Saitos are REALLY tolerant of grossly rich settings and will run that way all day long.

Do the same with an OS and the engine will quit, usually in flight when you throttle down for a second or two....

Typically if you can get the Saito started, it will fly that way, though not at best tune and it will consume copious amounts of fuel until properly tuned.

I've also had fewer problems with the exhausts and mufflers coming loose for some reason, on the Saitos. The OS mufflers and exhaust headers require that I drill and tap a set screw more often than not. Dunno why.


Run the OS until hot then tighten the nut. Not warm but right after landing. Mine have never just come loose and I use nothing on them like a lock of any type. I do like OS pumpers but if you requir a new diaphragm the carb has to be sent to OS, they won't just sell you the diaphragm. Cost of reapir with shipping was around $40.00 for a $2.00 part. Just one more reason I use YS, they sell every part for the engines and trust you enough to replace a part. The rich running of the saito is just one of the reasons I don't use them, I call them snot machines. Tune an OS and it stays in tune and is cleaner running.
Old 08-16-2011, 08:57 AM
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Default RE: 2 Stroke V. 4 Stroke


ORIGINAL: CowboyLifesaver

Use the pumped engines from OS and you don't need a muffler........lol
Because it falls off so quickly?

Though I've used OS pumpers on several planes, if the plumbing is not problematic, I just end up saving the money and forgoing the pump.
I've just not needed it.

Old 08-16-2011, 09:02 AM
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Default RE: 2 Stroke V. 4 Stroke

I find that fourstroke engines are more reliable in the air. They go through fuel at a slower pace, so you save on money there. I can run my OS70 and 90 on a lower nitro percentage than a two stroke, so fuel is cheaper.  

For scale models, only a fourstroke will do, not only because of the wonderful sound, but because you can turn a bigger, more scale prop. 

Best of all - almost no fuel on the sides of the model after flying! It drives me insane after having to squeegee the grass and oil conglomeration off my Escapade after each flight! 
Old 08-16-2011, 04:04 PM
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Default RE: 2 Stroke V. 4 Stroke

Just go for it! If you can confidently tune a 2 stroke, then give a thumper a try. I've had OS and YS and tinkered with friend's Saitos and believe what people say in terms of reliability. The Saito and OS are 1,2 respectivley. The YS engines provide incredible power, but at the tradeoff of finicky tuning. Once you get one dialed though...they are knida bad to the bone! OS has a really cool vavle adjustment tool kit that works on most engines and is worth every penny. As long as you don't try and run too much nitro or get them too hot, you'll find nothing more that a quick check of clearance is all that is required for the valve train.

One other thing that I don't think I read was the fact that a 4 stroke is much easier to make scale or custom exhaust systems for since they don't require an expansion chamber like a 2 stroke.
Old 08-16-2011, 04:30 PM
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Default RE: 2 Stroke V. 4 Stroke

I admit I have less experiance than the guys who are telling you to only use the more expensive motors.  But my 2 cents worth is I have used nothing but Magnum from the start (3 years) and have had zero problems and I paid alot less for my .91 four stroke.  Our local club expert brags on how sweet my Magnum runs.  Im just sayin....
Old 08-16-2011, 05:08 PM
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bigtim
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Default RE: 2 Stroke V. 4 Stroke

for a beginner learning to use a 4st engine get a tach its a helpful tool for tuning a 4stroke.

when I run up my engines before flying I usually get them to max RPM and richen them up about 300rpm so in flight when they unload the prop there not getting too leaned out.

over the years the same guys have posted the same thing about not needing a tach, so last week when I was dialing a 120 surpass I got off ebay that I was rehabbing, did a valve adjustment, and was tuning it on the test stand so I figured I would give the ear test a try,what I found was I was consistently off on the high end by at least 3-500 rpm sometimes more, even when I was sure I had peaked the engine, and when I did peak the engine with a tach I was 5-700rpm off my richening when I rolled back the needle,the 1-300 rpm changes are nearly imperceptible to the human ear really subtle sound differences .

I have pretty good hearing, but when your dealing with prop noise and not running engines every single day, you might not be as sensitive to the subtle changes to rpm, also running engines your not totally familiar with its not a bad idea using a little technology to help you along,I use a tach every time I run up my 4strokes not so much with the 2stroke engines.

with a 4 stroke a couple hundred rpm does make a difference in performance,when your swinging a larger prop it helps alot
Old 08-16-2011, 06:43 PM
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Default RE: 2 Stroke V. 4 Stroke


ORIGINAL: HellcatAce

Just go for it! If you can confidently tune a 2 stroke, then give a thumper a try. I've had OS and YS and tinkered with friend's Saitos and believe what people say in terms of reliability. The Saito and OS are 1,2 respectivley. The YS engines provide incredible power, but at the tradeoff of finicky tuning. Once you get one dialed though...they are knida bad to the bone! OS has a really cool vavle adjustment tool kit that works on most engines and is worth every penny. As long as you don't try and run too much nitro or get them too hot, you'll find nothing more that a quick check of clearance is all that is required for the valve train.

One other thing that I don't think I read was the fact that a 4 stroke is much easier to make scale or custom exhaust systems for since they don't require an expansion chamber like a 2 stroke.
I have found what is #1 and 2 are more about what the local hobby shops sell. In my area that is Saito and magnum but the magnums once used usually don't get bought again. The Saitos are alive and well in my area though. None of the local shops stock the OS four strokes on a regular basis so there aren't as many of us using them.
Another question I just have to ask is what is different between tuning a YS and any other four stroke? I keep seeing people that have never owned a YS state this over and over. I really would like to know what you think is so hard about a YS and maybe I can inform you about the problem. The older YS engines were/are a balancing act between the high end and regulator that some people were never able to figure out. An inquiring mind really wants to know.
Old 08-16-2011, 07:01 PM
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Default RE: 2 Stroke V. 4 Stroke


ORIGINAL: Admiral052

I am looking for information on the major (and minor) differences between the two beside how they operate and how they sound. I know nothing about the 4 strokes.
I like the sound of the 4 stroke and I am wondering what kinds maintence is needed, precautions, starting, storing, things like that.
I currently have experience with the 2 stroke but I would like to use a 4 stroke on my next Glow plane and I am looking for info

Thanks RCU group
Unless you want something really small, YS is hard to beat for power output, field manners and flat out reliability. Their 63-70 on the low end are just terrific as are the 110-115. Their middle of the road 140 sport is really simple to set-up and operate. On the high end, their 160-170 and their latest 175 DZ are true thoroughbreds.

Just a little more sophisticated on fuel set up but if you follow the instructions you should have success. These engines truly love nitro but I've run my 63 on 15% just fine. My 120's and 140's were usually run on 22% nitro and loved it. I no longer fly large 4 strokes only the small one. Just personal taste. For large stuff I've gone gas all the way
Old 08-17-2011, 04:39 AM
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Default RE: 2 Stroke V. 4 Stroke

I have only used OS and Saito. I have a saito 100 and a OS 120. I must say I love how easy the OS was to tune, and even out of tune it still runs smooth. The saito will run out of tune but is will knock really bad and shake you plane. Both my saito and os run smooth as glass but I would do a OS as a first 4 stroker. I have never seen a magnum in person but they look just like the OS and they probably run just like the OS and they are cheeper than the OS ( about $100 difference on all sizes). So if money is a big factor then I would go with a Magnum.

I have ran 2 strokes and 4 strokes. To me if you want speed, go with a 2 stroke and if you want scale or something that will give you a lot of pull power go with a 4 stroke. If noise is a big issues in your area, I would go with a 4 stroke.

Also saito are very light so, if you need noise weight I would not go with a saito or you could go with a saito but you will have to go with a bigger engine.
Old 08-17-2011, 06:11 AM
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Admiral052
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Default RE: 2 Stroke V. 4 Stroke

Thanks everyone for this great information. Reading all the stuff people put about four strokes on other discussions made them sound like they would be a real hassle but from the explanations you all put this is of course just not true. I think for my next engine choice down the road I will be gettinga Four stroke and seeing what that can do for my planes.

One question I do have still is, I believe that 2 stroke engines need to be mounted on a plane upright while a 4 stroke can be mounted upsidedown on a plane correct? Is there a difference between the two when you mount them to a plane concerning this and what your limitations are? I have noticed that this is a concern when mounting for a cowl cover.

Thanks again for this great information.
Old 08-17-2011, 08:04 AM
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Default RE: 2 Stroke V. 4 Stroke

Neither of the engines know they are inverted, they both will run well but you do need to make sure your fuel tank is mounted a little lower or you will get flooding and vapor lock sometimes. Just minor things. The four stroke tends to have fewer problems when inverted. An old trick is to mount the engine at a slight angle and not straight down. Just a little trick, mine are mounted straight down but I have been doing this for a little while.
Old 08-17-2011, 08:21 AM
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Default RE: 2 Stroke V. 4 Stroke

Two strokes will flood easier when inverted. But once adjusted for inverted run very well. In many cases I mount my two strokes at ninety degrees or a forty five exhaust down, This helps fuel draw on tanks that are not quite level or a little low. It also reduces flooding problems because the excess fuel can run right out the exhaust.
Old 08-17-2011, 08:29 AM
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Default RE: 2 Stroke V. 4 Stroke

Two strokes are really not problematic either when inverted.

The biggest issue is that fuel will pool in the glow element area, preventing it from igniting the fuel mixture.... particularly at first when the engine is not fully tuned.

I end up using longer plugs on all my inverted two strokers to keep the glow element out of the fuel. This seems to help as I run most of my engines inverted.
Old 08-17-2011, 08:30 AM
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Default RE: 2 Stroke V. 4 Stroke

I've got planes with the two strokes upside down, right side up, horizontal and four strokes the same way. You have to be a little better at the initial start up so as not to flood them (It's easier to do because the excess fuel will puddle in the top of the combustion chamber and not be pushed out with the exhaust) but they run fine in any position. Think about flying inverted, it wouldn't be so good if they quit running upside down. Just my two
Old 08-17-2011, 08:43 AM
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Default RE: 2 Stroke V. 4 Stroke


ORIGINAL: Jezmo

but they run fine in any position. Think about flying inverted, it wouldn't be so good if they quit running upside down. Just my two
Exactly...

Tank height, engine orientation, etc... have nothing to do with it once the engine is tuned and running.

Height only affects siphoning when the engine is sitting on the ground before flight, and once tuned with the engine at idle this is reduced to a very low amount... so a bit of pre-flight care fixes that... e.g. you often do not need to prime inverted engines.

Novices may have slightly more problems dealing with all of this, but an experienced hand can quickly acclimate them to the slight change.

Old 08-17-2011, 10:39 AM
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Default RE: 2 Stroke V. 4 Stroke

I've noticed that with all the small gas engines coming on scene, the price of used 4 strokes has dropped.

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