huey-pilot

My Feedback: (17)

Kavan makes a 50 cc twin four stroke that can be operated on gasoline or alcohol if you have the version that has the ignition module and spark plugs. The recommended fuel is alcohol since the engine runs cooler and develops a little more power. This engine has a wet sump and oil pump with a dip stick and magnetic drain plug. I have two of these engines with one of them on a 30 pound 1/3 scale cub. These are easy starting and smooth running engines. The engines are much smoother than my ZDZ 50 NG but are heavier and don't produce as much power.

RTK

My Feedback: (1)

Don't believe everything you hear or read about all the harm to the enviroment. I have a Biology and Chemisty degree. All that is said is not true. 99.9999% of the people doing all the talking (EPA & so-called enviromentalists) do not know what they are talking about! There is not enough time or space in any forum to correct all the misinformation. Just my educated 2 cents worth.

BajaBob-delete

Yes but if you park your car in a garage and sit in it with the engine running you die.So there must be something bad in the exhaust.
The feds and greenie weenies are gonna shove it down our throats any way.The special interest groups gain support from people that don't any better,to fight this first you have to educate everyone first,you gotta a better chance of teaching a cat to drive a car.

RTK

My Feedback: (1)

BAJA- BOY DID YOU HIT THE NAIL ON THE HEAD! My Dog is not bad, but the Cats' real tough to teach. CO kills us, but plants love it!

Dean Wise

this is good reading. I'm coming at this 4- stroke issue from another point of view. I race 1/5 scale cars that predominatly use the RC 230 zenoah engine that when modified puts out about 5 1/2 horsepower at 16.000 rpm with a tuned pipe. I'am going to try this four stroke conversion. I've been researching everything that I can find about the available 4-strokes out there. and have read about every conversion post there is. the honda gx 31 is about the right size but is gutless and they have a 50cc version but is a little to big. I thought about the shindaiwa and the stihl but not enough ponys. at this point I'm thinking of trying the YS 1.4 DZ or waiting a few months for the 1.6 DZ. My other option is the lazer 300 v-twin. a v type 4-stroke will fit were as the opposed are way to wide or I would have already tried the available saito and O.S. opposed 300's. the gas is the issue with me to because I need the fuel economy. that YS is going to suck about 2oz's per minute. but the laser can run on 0 percent nitro. I believe the market is ripe for a fourstroke on gas that is competitive. the go-ped world and the R/C boat guys are just waiting for a Mfg to step up and do it. the RC 230 Zenoah only came about because the 5th scale Mfg called FG who has approximatly 95% of the market world wide approached Zenoah and asked him to make a competitive 2 stroke. thats how it happened so it just needs a push from a market out there

tkg

My Feedback: (1)

Can't run the YS on gas even with a ignition installed.
The fuel system on a YS has silicone parts which won't work with gas.

Dean Wise

you would think that YS would go to a larger cube and try gas with their injection system on their DZ model. anyone know of a web site with that quattro 50 engine mentioned above from Italy

Willdo

Can't?
Which parts are not useable with gas?
There must be a way around that.
The motto of people who convert things is:- "If it doesn't fit make it fit" and I believe that similar thinking would apply in this case too!

lbianchi

The McCullogh 52 four stroke overcharged web site is: http://www.mcculloch.it (see "decespugliatori" and the
model "Quattro 52 pm"). There are not technical specification. See in my photo gallery for images and some data about the engine.
I'm working on the second version with lighter crankshaft and crankcase (400 gr. less) and new camshaft for more power and torque. My goal is over 5 hp and less 2.000 gr.

Luigi Bianchi

pete913

You bet! I remember when they said it was impossible for a top fuel dragster to top 200 mph in a quarter mile as well. Man would never fly either. I sorta doubt if YS or any of the present R/C engine manufacturers are gonna bring any real changes to life of their own accord. They have a vested interest in selling outdated technology until it simply won't sell anymore. I think any changes will come from modelers adapting commercial 4 cycles to R/C, and market pressure will eventually force changes onto the mainstream R/C manufacturers.

tkg

My Feedback: (1)

Regulator diaphragms are silicon. They would need to be made out of neoprene. You would also most likely need new needlevale assy with finer threads and a longer needle

WRK

My Feedback: (2)

A very interesting possibility for a strong 4 stroke would be a YS style engine of two cylinders scaled up to about 120 CC or so. Done right this engine should have the power of a 100 to 110 CC 2 stroke on gasoline like the DA, it would weigh a bit more but it would be much quieter and easier to muffle so it would not require 2 Lbs. of canister exhaust system for about the same power and should have very good midrange throttle response. The weight penalty (using a simple muffler) would not be as significant as the cost penalty.

Flierbk

rmh

sure looks easy to me -No problems -
How about a parts count?
bout the same as a two stroker?
let's see -a single valve has about 6-12 accociated pieces .
no way?
valve, valve guide, spring ,spring keeper(s) cam- that's six so far -on a really simple setup - not including seats, bearings etc..

But if you want one - make one - keep you out of the strip bars for a while -

WRK

My Feedback: (2)

Parts count is about the same as a YS per cylinder ( some parts count savings because you don't need double the cams or double the cranks etc. Weight gain about 17-20% over the 2 stroke, there are more parts and consequently more cost and this engine would have to be made essentially from scratch so to speak as there are probably not many parts that can be borrowed from other engines except possibly some things like rist-pins etc.

There is a twin four stroke engine that was built that used two cycle type bearings, needle bearings on both ends of rods, standard ball bearings on crank mains which allowed 100 to 1 gas oil mixture for lubrication (no oil pump and no sump). It is an air cooled in line twin, the valve mechanism (standard poppet valves) oiled by crank case recovered piston blow-by using crankcase pressure pulses to drive oil to valve stem and cam bearing/follower area via one way valve from crankcase. The displacement was 9.5 cubic inches and it produced over 15 HP. at 7500 RPM. The engine weighed about 18% more than an equivalent displacement 2 stroke with a single carburetor. That weight included a flywheel, magnets on flywheel for CD ignition. The exhaust system was a broad tuned expansion chamber/muffler. Different cam profiles produced different RPM/Torque curves and would move the HP peak about 1500 RPM depending on which cam was used. Special attention to flow restriction was made in the design of the engine, it had very good volumetric efficiency. The engine had a turn down ratio of 9 to one so it idled at about 850 RPM.

flierbk

Willdo

Not being really familiar with the YS setup, I'd better not say too much, but I feel sure that it could be overcome without too many problems.
It seems that a gas engine needs approx. 1/2 the fuel flow compared to alcohol fuelled engine requirements, so that could interfere with the amount of oil supplied to the engine, especially with a plain big end bearing, maybe a needle bigend?

Hans Meij

Have you seen this one?

http://www.4airpower.de/prod01.htm


Hans Meij / Modelvliegen

locoworks

the snag with trying to make a boxer twin 4 stroke with YS technology is that the YS uses the crank case pressure to force the fuel/air mixture into the rocker box chamber on every revolution, the so called supercharging. unless you had a large cylinder offset front to rear to allow for separate crankcase chambers you could not get the supercharging effect that makes these motors so gutsy. the guy with the idea of using the top ends off of an available radial gasser has a good idea, you just need a suitable crank, crankcase and camshaft plus other minor bits. but you will find it won't be as good as a similar weight 2 stroke or single, just look at the saito glowfuel boxers, gutless compared to the same weight in a single glow engine because the single would have more displacement?

Diablo-RCU

My Feedback: (1)

To Locoworks:
The YS supercharging system would work just fine with a twin.
In fact, YS built an opposed twin, but decided not to market the engine.
You would want to make it alternate firing in order to smooth out the power pulses, and then it would be about as smooth as a two stroke of the same displacement.
It would need a plenum chamber to store the compressed fuel mixture that was pumped out of the crankcase. Just like the one on the YS 120 AC. I'm sure I could design such an engine. Now, if one of the expert machinists would like to put their effort in the machining of the parts, they could actually get one running.

WRK

My Feedback: (2)

They do the split crankcase design all the time in 2 strokes should be no problem it does require a 2 throw crank but is not really a problem.

flierbk

rmh

Saito 100 is an alternate firing twin- with a little internal pump-- it fires in a kind of rat a tat firing sequence- nice engine - no power tho

Willdo

[quote]ORIGINAL: locoworks

The snag with trying to make a boxer twin 4 stroke with YS technology is that the YS uses the crank case pressure to force the fuel/air mixture into the rocker box chamber on every revolution, the so called supercharging. unless you had a large cylinder offset front to rear to allow for separate crankcase chambers you could not get the supercharging effect that makes these motors so gutsy.



Answer in reply to LOCOWORKS & DIABLO.
It is not necessary to have seperate crank chambers on a boxer 4 stroke twin, ( or a 2stroke boxer twin ) so long as the rods are not on a common crankpin, and you are using a 180 degree crank, the pistons are always opposing each other, thereby creating a pump.

Also you could have simultaneous firing of the cylinders ( dictated by the cam timing ), with a single cylinder sound.
The arrangement described by Dick Hanson I think,is of the rods on a common crankpin, has a sound more akin to a V twin,however, this arrangement nullifies crankcase pumping, so no good for crankcase supercharging.

For this system using the crankcase for supercharging using gas oil mixture, I believe that needle roller big ends are necessary, as spark plugs do not like the rich diet of oil required for glow fuel/plain bearing types.

Still think that it is pointless to use oil/fuel mixture in a 4 stroke, they will still pollute, ( ever followed a car which has a tired engine?).

Feel free to tell me if you think I might be wrong,but think carefully about it first, ( yes I, just like everyone else might have got it wrong, and if you can prove it to be wrong, then I'll admit it ).

WILLDO.

Daryl Martel

My Feedback: (3)

Hans - very nice! Very expensive, but very nice. That is German engineering - what a beautiful crankcase casting! That'll be a pretty exclusive owners club at that price. Regarding using YS engine parts to make a boxer twin, Saito parts would work too. Hmmm, 2 X 1.8 Cubes... now you're getting up to 60cc. I guess the big thing with such a project is the oiling aspect. Without running a pressurised oiling system to lube the connecting rod ends, and perhaps mist the cylinder walls, it becomes necessary to run needle bearings on the connecting rods doesn't it? Then you'd be mixing oil with the fuel anyhow. If you did that, the YS "supercharging thing" makes sense as it uses the crankcase as the pump anyhow and the moving parts would get their oil bath. I see on the German design Hans linked too it's got a proper oiling system. I can't help but think that's doing it right.

dave jones

Guys I have been flying the Honda 31 cc 4 stroke on a 10 ft air plane for over a year and 1/2 and it is one of the best engines that I have owned .
You can see video of the engine running on my web site at http://www.auav.net/engines.htm and http://www.auav.net/honda/index.htm
There is video of it flying as well Video of Honda GX31 Gas Powered 4-Stroke Airplane..
Dave Jones
AUAV

dave jones

Here is the link to the video of the Honda flying.
http://www.auav.net/2003_micro_air_v...ompetition.htm
Dave Jones
AUAV

Willdo

Glad to see someone happy with the little Honda, it has a sensible lubrication system for an aircraft 4 stroke, now if someone could give it a little more power it would be great and relatively cheap.

I do like that beautiful opposed twin mentioned by Hans too, but I'm sure it's too expensive for me, does it have a wet sump? looks like it does from the pictures.