mitchamus

I'm new to gas engines and was wondering why none of the engine manufacturers mark their engines as 2 or 4 stroke?

Are they all 2 strokes?

can you get a 4 stroke gas engine in a 2c.i. size that's not a weed wacker version?

I know it's pretty obvious that they are two strokes, but RCV 4 strokes look like two strokes so I though it best to check...

Mitch.

smokingcrater

the only production 4 stroke out is made by honda, and is a weedeater conversion. remember gas engines don't have the power/weight of glow to start with, so a 4 stroke gas is really lagging in that department. I haven't heard of anyone running the honda 4 stroke conversion yet, it is heavy and also appears to have a wet sump oil system, meaning inverted could be very bad...

Antique

My Feedback: (4)

And Stihl, Shindaiwa, and Ryobi, to name a few...The power/weight ratio is not very good yet, but they're making progress, and the Stihl and Shindaiwa use oil in the fuel just like a 2 stroke, no oil sump....

BajaBob-delete

Zenoah has a 26.5 cc four stroke out there too,by far the Honda is the best,the flying weight is less than 5 pounds.Honda designed the oil systems to operate in 360 degrees of angle so inverted is not a problem.It has an oil resovoir but is not a wet sump.It turns a 18/8 to just over 6000.

Hans Meij

Seidel, RCS and 3W have their radials.
The new 250cc 3W does 20hp on 5 cylinders. That is 4Hp for each 50cc cylinder.
Time to derive a single from this radial?

Hobbsy

My Feedback: (102)

The Ryobi 26cc fourstroke can be run in all positions also, but like the others it is heavy and not very powerful.

pete913

I'd really like to see someone do the development work necessary to make these things successful in RC. That old stuff about 4 strokes not having the power potential to me is BS. Anyone seen a winston cup or an NHRA championship won by a 2 stroke lately?4 stroke power potential is there.Sure these little weedies don't match present day 2 strokes power wise, my guess why is because , most of 'em have an intake and exhaust tract about like a farm tractor engine, lousy combustion chamber shape, valves and ports half the size they could be, low speed industrial cam timing, compromise ignition timing etc. Put a box muffler off a weedeater, on your 3w and see how much power it makes. Personally, I'd love to see a mainstream manufacturer, such as Honda, get into this. The heaviness of the engine could be trimmed a lot I'll bet, and maybe it'd wake up OS,YS, Saito, name your favorite, to some facts about 4 cycles. No 1. why on earth does a 4 cycle engine need glow fuel and a glow plug? It doesn't. Put the oil in the crankcase where it belongs, and quit diluting the fuel mixture with it. Diluted fuel mixtures should be the province of the 2 stroke, not 4 strokes. Put on an ignition system, a good Hall effect system, with controllable timing, weighs a few ounces, offset by the power increase of being able to run straight gasoline, and getting rid of the heavy magneto flywheel. put on a REAL carburetor, with mid range metering etc.Change cam timing to something appropriate to the rpm range used in a model airplane, with valve and intake/exhaust port sizes to match. A 2 stroke operates with a compressed fuel charge that's half old exhaust, and oil in the fresh charge. No 4 stroke suffers from these obvious defects in its operation, or shouldn't anyway.

Diablo-RCU

My Feedback: (1)

Four stroke gassers could be designed to compete with the 2-strokes on power. They would be more costly than a 2-stroke and also have more of a "shake" from the power pulse, and it would be taller. Take a look at a YS 4-stroke, then think what would be required to make it run on gasoline. Add needle bearings to the connecting rod and rocker arms, plus a roller cam, a diaphragm carb, add an ignition, eliminate the standard regulator and tank pressure system, and run a gas/oil mixture like a 2- stroke. Considering a YS 1.40 costs about $500, you could probably sell it for about $750. And that would be for a baby 4-stroke around 40cc.

rmh

the new Honda Elite 80 is a single four stroke scooter - probably as good as it gets-

pete913

Nonsense. Needle bearings wouldn't be necessary, and neither would any kind of gas /oil mixture. Do full scale airplane engines have either? Do full scale 4 stroke motorcycles run on a gas/oil mix? Nope. Hardly any full scale airplane engines have any kind of inverted oiling system either, although both the small Honda and Ryobi 4 strokes have an all position oiling system that'd work fine . My point is that the oil would be in the crankcase, not polluting the fuel mixture, just like full scale. They'd oil much better with a system like that than they do currently with glo fuel. The ignition systems are already commonly available as aftermarket packages for the smaller 4 strokes. The only means of controlling ignition timing in a glow engine is due to the heat range of the glow plug, the compression ratio, and the amount of nitro in the fuel. Thats technology from 70 yrs ago. So why do we still have small 2 stroke glo engines? simple, you can buy one for $60, they make a fair amount of power for their size, and there's a " we can't change the status quo" attitude among the manufacturers of higher end engines. YS, OS, and Saito are hardly the last word in 4 stroke technology. If they were, you'd already be seeing some of these changes incorporated by them. I for one wouldn't shed a singe tear if someone else came along and took us out of the dark ages with some new technology. Even if it were more expensive to start with, the savings in fuel costs alone over the life of the engine would more than justify it. As well as putting 4 strokes on an equivalent, or higher plane powerwise than 2 strokes, where they could easily be.

Diablo-RCU

My Feedback: (1)

Sat Pete:
The reason you don't see 'em, is because there is no market for the kind of engines you propose. What works for full scale, does not scale down very well for a model. No manufacturer wants to make a huge investment in something like that with an unlikely chance to make some money.

Antique

My Feedback: (4)

A Zenoah 4 stroke 26.5 ?????
Weight..The extra pieces and parts weigh more than a crank and piston....
I converted a new Shindaiwa, the latest technology, COPIED from YS...Not enough power for the weight..Oil in the fuel is not a big deal....
Honda had some 4 cycle racing motorcylces, 125 cc 4 cylinder, sosmewhere around 22,000 rpm, a power band about 500 rpm wide..They had to use 8 speed transmissions to be able to use the power..

RTK

My Feedback: (1)

RCNIGN1- Doesn't that oil in the gas defeat some of the enviormaniacs purpose of using a 4-stoker?

Antique

My Feedback: (4)

Probably, but the 4 stroke weedies that use oil in the fuel have ball and roller bearings throughout, and the fuel passes through the crankcase before going to the carb...Takes WAY less oil than a normal 2 stroke with bushings on both ends of the rod, and since the cam is some kind of plastic they can get away with it....

Diablo-RCU

My Feedback: (1)

Most of the 2-stroke emissions are from unburned gasoline, not unburned oil. The intake mixture coming through the transfer ports can exit out the exhaust port before the piston closes off the exhaust.

pete913

The markets there right now. You can't buy things that aren't available. The only trouble is that YS and the rest want to keep selling their cheap outdated crap, and there isn't the market pressure YET to make them change to modern technology. It's the old story, If you have made something, and it sells, keep making it until no one's buying it anymore. I remember when almost no one thought anyone would buy model 4 strokes in the first place. My how times change. The slow change will start at the high end engines for sure, as it always does. Do you actually believe that someone ready to plunk down, say $3500 on a new 4 cylinder 3W wouldn't pay $4000 for a 4 stroke with equal or likely more power and no fuel mixing? They'd be lined up at the warehouse door. I wouldn't expect it to filter down to a .40 size trainer engine. Price is and always will be the major deciding factor in those engines.

rmh

Pete - build one -
It ain't that easy to scale down and get the results you say are available.
Again -look at the newest little Honda 4 strokers -for th public use - and that's what we are -- it don't get no better.

pete913

Thats only because the little Honda is a purpose built engine, designed to run a weedeater, not a propeller. I don't see too many lawn boy engines in 40% extras either. Thats like comparing a formula one engine to a briggs and stratton.

tkg

My Feedback: (1)

Just to muddy the water a bit. Two models have flown across the Atlantic, one with a Enya 155, the other with an OS 61. Both 4c both running gas/colman fuel.
I showed a gas Enya at Toledo a few years ago, lots of intrest until the price came up. Then the coment was "why bother I can run a 90 2c for a $100"

WRK

My Feedback: (2)

Going to 4 cycle gives you a quieter engine and one that muffles easily, the draw back is weight and performance but a YS style 100CC twin made for gasoline would interesting.

Want power and low weight? The Wankel is really good for power in a small package and low weight, the problem is cost and a fairly hot exhaust that must be contended with, muffling challenge is between 2 stroke and 4 stroke as far as noise is concerned.

Want the power we have now in the 100 CC class engines but with smoother running and much better transition and fuel economy plus much lower engine shaking forces? A good fuel injected 2 stroke is hard to beat. The problem is cost and some weight gain.

Europe has some fuel injected 2 stroke scooter engines that are in production now and there are Personal Water Craft 2 stroke engines that have been made for several years with a direct fuel injection system made here in the US.

There are changes being made to small engines now because of the EPA, they are setting new standards for emissions, this will ultimatly effect the R/C industry in several ways in the not too distant future.

Some interesting configurations are being looked at by some R/C engine manufacturers that may well change the 100+ CC engines we use now, this may be sped up by the EPA.

Bill K

rmh

the Honda is not a weed eater engine --it is a scooter engine.
Any of you guys build engines?
Hondas? Chevs? Studebakers? Triumph? Maxwell?
As you make the four stroke small - things have to change.
As simple a thing as a rod cap and bearing get to be pretty tricky.
The fob on my car keys is a conrod from a '40's O&R twin (two stroke ) and it has a rod end cap .
I just threw that part in for other geezers --

pete913

Do I build engines? No. I'm a toolmaker, and I build injection molds and die tooling everyday that'd make an engine seem like falling off a log by comparison. Don't believe that? Have you ever created CAD geometry and toolpaths over it using a CAM system to produce a cylinder head on a 5 axis CNC machining center? I have. If you take a good look at the average model engine, the machining and EDM techniques necessary to produce the casting dies are about 100 times more complicated than the actual machining of anything in the engine proper. I make my living doing CAD design and CAM assisted CNC machining. I have one job, I don't need another. To tell me that something can't be built, or that it won't scale down is pretty funny really. This "can't do" attitude is why this country has lost most of its industrial base. If you talk to the average car guy, their idea of " building" an engine is assembling it. I got news for you, the guys who built it are all employed by the original manufacturer.

rmh

Now I understand .

mitchamus

Thanks for the interesting reading guys.

I just checked out the RCV website, and they have a 50cc prototype engine that they are developing,
as well as there are notes about building engines for UAV's. (hopefully 150-200cc!)

hopefully through some of this work, they'll market the 50cc + engine for model use.

I think that if they do market this engine, it would be a hit, even if it was they're
CD (crank Drive) range of engines. I just read that they're new .91 size CD 4stroke
is about the same external dimensions as a 50 4stroke, aswering som of you guy's concerns about size and weight...

For me I'll never go back to 2 strokes, I just love the sound and the torque of the 4 strokes.
A 150 saito screaming in a dive, combined with the whistle from the cowl.... you just can't beat it.

Maybe I could sign up for their 50cc engine test.... and just not return it...

Mitch.

Antique

My Feedback: (4)

The sleeve valve technology that the companies are calling 4 strokes goes way back to the '20s...It's a variation of the old Knight engine that had rotating cylinder liners that acted like valves..There's not much new under the sun...A 4 stroke to me is an engine with at least one intake and one exhaust valve operated by one or more camshafts..
SEMANTICS....