KB9STD

My Feedback: (1)

Anyone know if the 4 stroke trimmer engines can be converted for RC use? Is the oiling a problem when the engine is inverted?

huey-pilot

My Feedback: (17)

I have a four stroke Ryobi string trimmer and edger, it starts very easy, doesn't have much power and weighs a ton. I don't think that this would be a worth while conversion due to the weight, I don't even like it as a string trimmer due to the weight.

Willdo

Some of them use fuel / oil mix as in two strokes, with no oil control ring on the piston.

The Honda GX 25 OHC.uses a seperate oil tank, with an agitator which whips the oil into a mist and uses the pumping action of the underside of the piston combined with one way valves, to distribute this "mist" through the engine, and return it to the tank. This way it can be used at any attitude as with a 2 stroke, - at the same time keeping the oil out of the combustion chamber with an oil control ring.
It is a simple and effective system.

I believe they are all being tried as conversions by quite a few people.

BajaBob-delete

Did you do a search before posting this question?

Anything can be converted to anything,you could put a steam engine on an airplane if you wanted to.
Honda doesn't have problems inverted,some of the others may,any wet sump four stroke should not be run inverted.
Basicly if you plan on doing something with anything other than a 2 stroke zen your wasting your time here,because the anti four stroke crowd comes in and hijacks meaningful discussions with thier worthless drivel.
You don't see four stroke fans jumping into 2 stroke threads complaining about unburned hydro carbons pollluting atmoshpere or dirty smelly exhaust.

Volfy

My Feedback: (23)

Actually, I love both of my 4stroke Ryobi trimmers for wacking weeds. No 2stroke oil to foul up the plug and spew smoke for me to suck on. Plus it's very quiet (relatively of course). The Echo blower I use, on the other hand, has a 21.2cc 2stroke that is loud and smelly. Not nice.

As model airplane engine, however, the 4strokes weedies are too much weight and too little power. If you plan on powering a 1/4 scale Cub, that's fine. Otherwise, pick another garden power tool in your garage to canabalize.

BTW, the wet sump oiling system in both my Ryobi 4stroke trimmers work just fine upside down.

Willdo

Volfy,
I haven't seen the Ryobi as yet, but I'm prepared to bet it isn't a wet sump type. Wet sumps definitely will not work upside down, - dry sump perhaps?
To work upside down, the sump must be seperate from the crankcase - surely?
please correct me if I'm wrong!

aero nut

Actually go to jag engines website and you will find a cinversion of the ryobi 26 cc 4stroke engine with all the pertinent data. as I rfecall ryobi claims it can be runned in any position even inverted because of their new sump design

DougT

My Feedback: (1)

The Ryobi is a wet sump eninge and will run inverted but isn't as happy as right side up. Also, if you store it inverted, it tends to leak oil past the rings and out the case vent, screwing up the combustion chamber and your floor. Once running, doing loops and flying inverted is fine but I lost nearly 1000 rpm static with it inverted.

Volfy is right, they aren't power-houses but are fun, quiet, clean, and super economical. I can burn about 12 per hour of putting around.

From reading other threads, it sounds like the Honda GX25 and the Stihl 4-mix will be more powerful. I also haven't seen any numbers on the Shindaiwa engine.

Doug

Willdo

William
Went to the Jag site, - didn't find anything on the Ryobi four stroke!

aero nut

Sorry! willdo it used to be there don'tknow why they removed,but they did havea conversion kit for it

BajaBob-delete

They aren't power houses stock,but when properly modified they are a completly different animal.

DougT

My Feedback: (1)

Try these links for more info on 4-stroke conversions:

http://www.rcuniverse.com/forum/fb.a...think%2Cflying

and this:

http://www.rcuniverse.com/forum/fb.a...8000&key=honda

and this:

http://www.rcuniverse.com/forum/fb.a...6815&key=honda

and this:

http://www.rcuniverse.com/forum/fb.a...2957&key=honda

and this:

http://www.rcuniverse.com/forum/fb.a...2298&key=honda

and this:

http://www.rcuniverse.com/forum/fb.a...7643&key=honda

and this:

http://www.rcuniverse.com/forum/fb.a...4597&key=honda

and this:

http://www.rcuniverse.com/forum/fb.a...6887&key=honda

and this:

http://www.rcuniverse.com/forum/fb.a...3941&key=honda

and this:

http://www.rcuniverse.com/forum/fb.a...0795&key=honda



Enjoy reading! There's a lot here to digest.

Doug

BajaBob-delete

Maybe it would be easier to find four stroke information if the devoted a forum to it.

Volfy

My Feedback: (23)

Bear in mind that Ryobi has made 3 different 26cc weedie engines. GEN I, identified by a single crankcase casting and a metal backcover, had some problem with the breather vent such that it did not operate very well inverted. Ryobi redesigned it slightly to fix the problem and designated it the GEN II, which sports a black plastic back cover. This is the most popular version powering Ryobi's 800 and 900 series weedwackers.

Later on, Ryobi came out with a completely new 4stroke design for their higher-end "professional grade" garden tools. The GEN III engine has a 2-piece aluminum (or maybe magnesium) clamshell crankcase, which forms the wet sump, thus eliminating the need for a "drain pan" back cover. This version is supposedly much lighter and more powerful. The 1/4 scale Cub shown in the Jag Engines website ( now curiously missing) is powered by the this GEN III engine.

The 875r and 1079r that I actually use to wack weeds have the GEN II and GEN III engines, respectively. I like the Ryobi 4strokes for their functional simplicity. Lattely, others have come up with fancier 4stroke designs, some of which even uses gas-oil mix like the 2-strokes. To me, that defeats one of the main purpose of going 4stroke - eliminating particulate emission from burning oil.

Anyhow, I'll probably end up converting the 1079r just for the fun of it. For now, I've already got too many conversion engines than I know to do with.

BajaBob-delete

That grey unit is a spitting image of the redmax/zenoah it shouldn't be surprising however as the Ryobi die casting plant is owned or in joint operation with Komatsu/Zenoah.