Terbough Bob

My Feedback: (10)

I was wondering if I could mount a Gen III or whatever the engine out of the 1079R trimmer is called, upside down or on it's side? Thanks!

Volfy

My Feedback: (23)

At home, I use a 1079r Ryobi actually as a weedwacker. I've had it upside down and whichever way, and it ran just fine.

FWIW, I bought it to replace my old 875r, which has the cheaper version of the 26cc engine. The genIII engine on the 1079r is markedly more powerful.

Terbough Bob

My Feedback: (10)

Excellent! Next question is- would it fit inverted inside the cowling of a Dynaflite 89" Decathlon or a Sig 1/4 Cub... Perhaps I should be asking this in the Giant Forum?

donalddresser

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The great thing about gas engines is that they have a pumped carb and they use a spark plug not a glow plug. The position of the cylinder has not effect on how the engine runs. The pump in the carb prevents any siphoning of fuel and there is no glow plug to get flooded out. I converted two engines and they run great

Terbough Bob

My Feedback: (10)

Hi Donald, I'm aware of the carburetion, but I was asking about inverted mounting because of the oiling system associated with the Ryobi four stroke gasoline engine.

Volfy

My Feedback: (23)

I am pretty sure you'll have little problem hiding most of the engine inside the Decathlon. I just finished a Sportsman Aviation Super Decathlon 86" wing with a Homelite 30cc 2stroke hidden completely within the cowl, except the B&B muffler stinger tips and the sparkplug cap. The Ryobi genIII 26cc has a fairly large aluminum (or Magnesium?) crankcase, which doubles as the oil sump, but I still think you'll be allright.

I am not so sure about J-3 Cubs. I have two WM 1/4 J-3 Cub ARFs, and their cowls are much narrower.

Volfy

My Feedback: (23)

About the Ryobi 4stroke oiling system, yes they've always had a wet-sump system with baffles such that adequate lubrication is maintained regardless of engine orientation. The gen I 26cc with metal "oilpan" reported had a problem with the baffling and didn't work well inverted. The later gen II with plastic oilpan and the Pro-grade gen III are supposedly worthy of the 360deg orientation claim.

I believe the gen III is quite a bit lighter weight than the gen I & II, though I don't have first hand knowledge since I've yet to take apart mine to see. Please let me know what you find out. I'm very interested.

Terbough Bob

My Feedback: (10)

I just checked out that Decathlon and I'll admit- it's one of the nicest ARFs I've seen. And for the price, it's very tempting... How's it fly? I'm slowly convincing myself to get back into model aviation; it's been about eight years since I've flown. When I last flew, it was a Midwest Hotts II with a hairy- chested 60 yanking it around. I'd like something bigger, more scale, and a bit more relaxing to fly this time around. I'm not scared of building, but for under $300 for a very pretty ARF, I'm awefully tempted.

Something else I've been thinking about as well is a Balsa USA 1/3 cub with a four cylinder four stroke fabbed from Gen III 26cc Ryobis. Perhaps an ambitious engine project, but if it could be pulled off, do you think it would be too big to be scale looking, or weigh way too much? The only reason I'm even considering such an engine build is cost- for $1200 or thereabouts, I can get an OS Pegasus that is known to fly the plane. However, it's glow, and costs a grip. If I could buy four Ryobi 1079R trimmers for $560, and spend $100 in aluminum and bearings for the crank case, I'd rather do that. It wouldn't matter if it took me 100 hours to build the engine; that's just as fun as flying it. One last question if y'all are still reading... since the Ryobi in original form puts out about 1 HP, would four of them as one engine produce 4 HP? Up until last night, I've never even considered adding cylinders to an engine, so I'm unsure if the increase in specific output stays linear or is exponential.

God, I feel like a no0b for asking that! lol

DougT

My Feedback: (1)

Bob,

I've been running the Gen II. for a while now and am fairly happy with it. CH ignition makes it idle awesome and the sound is too cool. BUT, I did mount it inverted for exactly the same reasons as you and lost about 1000 rpm and the idle was not reliable. It also wanted to puke out some of the oil from the case breather tube. I understand that the Gen III have the breather on the valve cover. Is that correct? It may make inverted better or worse. I'll take a head-on pic of the Ryobi with a height and width measurement and post back here.

Check out this. I want to start building it this summer. The main holdup is milling the crank for it.

scottfl78

Hey guys I have been looking into converting a Ryobi or Homelite when I saw the Ryobi FS advertised... If understand correctly it is oil injected and will have to have an oil tank... Is this a pain in the butt for R/C? What about power vs. 2 cycle? Also is there a lot of added wieght for the lifters, valves etc... I haven't even heard one run... Do they sound more scale? Not that a 2 cycle gas engine doesnt sound cool... Just havn't heard of converting the 4 cycles... Thanx a lot

ZAGNUT

My Feedback: (1)

if you're buying a 4-stroke trimmer for a conversion then check out the offering from shidaiwa...no oil sump, runs on premix and is supercharged like the YS 4-strokes. no probs at all with inverted mounting. don't know what the cost is compared to the ryobi but i'm betting that a short-block is available.

stihl also has something similar but they've become a bit too anal-retentive lately...not worth dealing with


dave

Kostas1

DougT did you ever finish this opposed twin ?

I'm really interested...