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Ryobi 26cc Four-Stroke

Old 02-16-2006, 11:33 PM
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rrudytoo
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Default Ryobi 26cc Four-Stroke

Okay, I could use some advice here. I just bought a Ryobi 26cc four-stroke off eBay and I honestly don't know a thing about this particular engine. I would like to use it in something like a Balsa USA Fokker DR-1 or, maybe, a D VII. But first, a few questions.

Is it safe to run this engine inverted knowing that the oil is kept in a sump? What prop sizes are suitable for this engine? Being a four-stroke, it should make its power at the lower end of the rpm band. Would it be worthwhile to toss the magneto and convert it to electronic ignition? From those who have been using this engine, any suggestions, comments or things I should be aware of?

Thank you all in advance and I look forward to hearing your input.

Al
Old 02-17-2006, 12:24 PM
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pe reivers
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Default RE: Ryobi 26cc Four-Stroke

I have one waiting for a project that needs to be lazy.
The engine has a wet sump, and if I look at the system, it is not meant for prolonged inverted running.
Old 02-17-2006, 12:56 PM
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Default RE: Ryobi 26cc Four-Stroke

Maybe with 2% 2cycle oil added to fuel may help when inverted. Or even 4%....woth a try. Capt,n
Old 02-17-2006, 03:20 PM
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pe reivers
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Default RE: Ryobi 26cc Four-Stroke

I have contemplated that option, and just liberally lubricate before each flight. After all, it is not a high performance engine. With good high grade synthetic oil it might work. That oil clings like glue to anything metal.
Old 02-21-2006, 12:01 AM
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DougT
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Default RE: Ryobi 26cc Four-Stroke

There have been many, many threads on this engine. Do a search for "ryobi" and "26cc" under the Engine Conversion page and you should get 6 pages of results.........

Here are the most significant threads, have fun reading.... All the info many people have compiled is there. No sense on reinventing the wheel.



http://www.rcuniverse.com/forum/m_12...tm.htm#1252674

http://www.rcuniverse.com/forum/m_11...tm.htm#1144114

http://www.rcuniverse.com/forum/m_15...tm.htm#1593098

http://www.rcuniverse.com/forum/m_13...tm.htm#1324434

http://www.rcuniverse.com/forum/m_12...tm.htm#1290555

http://www.rcuniverse.com/forum/m_11...tm.htm#1175344

http://www.rcuniverse.com/forum/m_95.../tm.htm#953526

http://www.rcuniverse.com/forum/m_79.../tm.htm#795268




Having said that, I was very interested in this engine 2-3 years ago and spent countless hours thinking about or working on/testing this engine. I had a custom TIG welded aluminum muffler built, put on a CH Ignitions ignition on it, alum prop hub, tried 3-4 different carbs, tried it inverted...... Not a real powerhouse and 4# RTF(w/muffler/mount).

You can't just swap on any old carb, as the 4-stroke has a small return spring on the pump diaphram because the 4-stroke carb operates off of vacuum pulses. I tried swapping all sorts of springs into different carbs but nothing worked as well as the plastic rotary 9.5mm stock carb. I will someday try a regular 2-stroke carb and put a "T" fitting in the crankcase breather tube hose and tap directly into the carb pump to supply positive pressure pulses.

You "can" run this motor inverted but it doesn't like it. Mine lost about 1000 rpm being inverted. You will also have to store your plane upside down to prevent the oil from running by the rings and into the head/plug/valves.
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Old 02-21-2006, 01:29 AM
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Default RE: Ryobi 26cc Four-Stroke

The thing about torque at lower speeds doesn't seem to work on these small 4 strokes..I converted 3 or 4 diffferent brands, 25 to 34 cc, OHV and flathead, oil in the sump and oil in the fuel...The Shindaiwa 34cc was the best, still no stronger than a G23 and not able to run more pitch any faster...I think the Shindaiwa turned my Mejzlik 18-6 about 8000 rpm after putting a larger carb on it...A Stihl 64.9 was the same, no more torque than a G62...These things are just not designed to run slowly with a big load.....A 25cc Homelite will blow any of them away, and be lighter and cheaper....Close, no cigar...
Edit to say, never tried a Ryobi but wouldn't expect anything different....
The Honda GX35 might be better, never tried one of those either...
It has oil in the case, so no upside down on that one either...
Old 02-21-2006, 09:17 AM
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Default RE: Ryobi 26cc Four-Stroke

preivers: Thanks for your reply. If any of these engines has needle bearings on rod, it seems like they may even run on glow fuel. Remove all heavy ignition parts. The lube part should work like common 4 stroke glow engine. A cam for torque could be developed...for those with master skills!! The sound of a 4 cycle engine and some are more fuel efficient ... is the draw to these engines. We do not have to re-invent the wheel...but we can make the wheel better! Thanks Capt,n
Old 02-21-2006, 02:27 PM
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Default RE: Ryobi 26cc Four-Stroke

Capt'n,
If you like to tinker, this seems the engine to give a try, though the internals are quite delicate. I have filed own design camshafts for side valve lawn mowers. Made them from a car drive axle. It is not that hard to do if you know the principles of valve motion control. I doubt however, you could do the same with the small Riobi parts.
Glow fuel will not provide the lubricity you need. The bearings are not designed for the diluted oil mix that our glow engines use.
Old 02-21-2006, 02:34 PM
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Antique
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Default RE: Ryobi 26cc Four-Stroke

Far as I know all the weedies have roller bearings and use 50-1 oil in the fuel...Glow fuel is at least 15% oil....nothing diluted about that
Even converted Supertigres with bushing rods can use 8 or 10% oil..
Old 02-21-2006, 03:26 PM
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Default RE: Ryobi 26cc Four-Stroke

Can one of you guys reading this forum....pop the oil pan off one of these 4 cycle Ryobi engines or any engine lile one to see what we got inside for rod bearings ...ect. Be sure to post a couple of views. Thanks Capt,n
Old 02-21-2006, 04:40 PM
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Captain Ramius
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Default RE: Ryobi 26cc Four-Stroke

The Honda GX35 might be better, never tried one of those either...
It has oil in the case, so no upside down on that one either...
Wrong!

The GX35 uses the same oil system the other mini four strokes from Honda , it can run and be stored inverted. It is and remains the only four stroke that runs on plain gasoline (no premix) that can run inverted.
[hr]
A cam for torque could be developed...for those with master skills!!
CaptinJohn
Go to ASMBA and talk to Bob.
Old 02-21-2006, 05:18 PM
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Default RE: Ryobi 26cc Four-Stroke

RCIGN1,
The 64.9 Stihl engine you converted, was it the 3 or 4 hp version? The BR500 blower is 3 hp while the BR550 and 600 are 4 hp. I'm thinking about one of these in 1/3 scale Cub, any thoughts? Is the ignition cam driven? Or does it fire every revolution?
Old 02-21-2006, 06:21 PM
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pe reivers
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Default RE: Ryobi 26cc Four-Stroke

Ralph,
Glow engines have bushed bearing about as wide as the pin diameter. Gas engines many times have much narrower bearings, like 1/2 D wide. In methanol engines the oil is diluted indeed, but glow engines get by because of the generous bearing surface that allows an oil wedge to operate despite the low viscosity and reduced oiliness.
If the engine has a needle big end bearing, it certainly will fail if used with glow fuel, due to the combined low viscosity oil/methanol mix, and acid combustion by-products.
Been there with an converted moki gas engine.
Point to ponder: MVVS also reverted to plain bearings in their 26cc and 35cc glow engines after initially having needle bearings.
Old 02-21-2006, 11:16 PM
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Antique
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Default RE: Ryobi 26cc Four-Stroke

Tony...I converted 4 of those, all were 550s....The ignition is a flywheel mag, fires every revolution....Normal rotation using the flywheel ignition is clockwise viewed from the front, if you make it that way it will need a pusher prop....I made 2 of each, all 4 had electronic ignition with syncro spark...the carb is a Zama, not very adjustable...You can change the carb to a Walbro 2 stroke carb, there's a pressure fitting in the case that works for the pulse...doean't take a very big carb, a WT76 works just as well as an SDC80...
Pe...We run our GT80s on glow fuel with about 25% nitro and 6% synthetic oil, no problems after 2 seasons....I have a 289cc twin here that's always run on methanol and 8% Klotz with no nitro, still looks new inside....All these have fairly wide roller bearings, probably at least as wide as the pin diameter....
Old 02-21-2006, 11:20 PM
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Default RE: Ryobi 26cc Four-Stroke

Peivers: We are talking 4cycle engines with oil in the oil sump or pan. Now if that oil is about the same type of oil you use in the fuel as a back up...the cross contamiantion should not be that bad. This(oil system) works in YS, OS, Saito, Enya 4 stroke engines. So I say again....mix your glow fuel for the 4 stroke Ryobi with some oil for a back-up for lube in flying inverted. I do not think it has been even given a good try yet. May be wrong Capt,n P.S. It may need a over flow tube to get rid of oil that passes the piston and collects in pan.
Old 02-22-2006, 04:38 PM
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Default RE: Ryobi 26cc Four-Stroke

Ralph,
The engines you converted also turned clockwise viewing from the front? It seems to me a camshaft change or reversing the direction of rotation of the cam is necessary. Never looked for a pusher prop in the 22" to 24" size. I would image selection is somewhat limited! I understand why I haven't seem more about this engine on this forum now. What was the final weight?
Thanks
Tony Hallo

Old 02-22-2006, 04:43 PM
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Default RE: Ryobi 26cc Four-Stroke

Just checked Zinger web page and found to my surprise a rather large selection in the 22-24" sizerange. For a Cub, a Zinger works for me.
Old 02-22-2006, 09:03 PM
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Default RE: Ryobi 26cc Four-Stroke

Don't remember the exact weight, somewhere between 5 and 6 lbs...Try a search, maybe it's there....
They turned clockwise because the flywheel was on that side of the crank..I made 2 using the other end and mounting it that way...Neither way is easy, the clockwise rotation engines had stronger mounting points on the rear side...
Engine turns the same either way, prop rotation depends on which end of the crank you put the hub on....
Old 02-23-2006, 10:55 AM
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Default RE: Ryobi 26cc Four-Stroke

Capt'n,
There may be some confusion here. I am not talking glow fuel.
I am suggesting a non-proven theory to use gas/oil mix with 10% oil, just like the 4-stroke glow engines use in their glow fuel mix.
I was contemplating this construction, without any oil in the oil pan (dry sump system)
To do this, I would add an oil inject feature, so a generous amount of oil coild be squirted on the main crankpin bearing with the piston in top dead position. In combination with the oil mix, it might serve very well.

OTOH, there seems nothing wrong with having oil in the sump, and just fly positive G-forces all the time, with occasional inverted flight (negative G) of short duration. Even a side mounted engine probably will work well using the wet sump.
Old 04-20-2006, 11:36 AM
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Default RE: Ryobi 26cc Four-Stroke

Fellow Ryobi 4 strokers...

I know the answer must be somewhere in these extensive threads, but having acquired a 26cc 4 banger, and having run it yesterday, I discovered what most of you probably already know about carburetion:::

Low speed is spot on, High speed is grossly lean, there is no way to adjust either!

If the "ramping" in and out of the throttle barrel were more pronouned (steeper), this problem could be remedied, but I have no way of machining such a thing.

Does anyone know of a suitable replacement 2 needle carb for this 26cc 4 stroke Ryobi?

I have seen the suggestion of a Walbro WYK, but the exploaded view looks very different than the stock WLK. I cannot tell if this is a bolt-on replacement?

THANKS ALL
Old 04-20-2006, 04:12 PM
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Default RE: Ryobi 26cc Four-Stroke

Why not just re-jet the carb?
Old 04-20-2006, 04:45 PM
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Default RE: Ryobi 26cc Four-Stroke

Only Walbro I know of that has replaceable jets was used on a BIG chainsaw..It came from the factory with a normal size jet..If it was to be used at high altitude there was a leaner jet available..Only 1.....It was a very small brass piece held in by a thin steel spring clip....`
Old 04-20-2006, 07:00 PM
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Default RE: Ryobi 26cc Four-Stroke

There is no way to rejet.
This carburetor is fixed as is. I've never seen anything like it.
Old 04-20-2006, 08:45 PM
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Default RE: Ryobi 26cc Four-Stroke

The WYL on the Hondas have brass jets that you can replace or redrill and naturally are available for 4 strokes. You can go to that.
Old 04-21-2006, 08:05 PM
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Default RE: Ryobi 26cc Four-Stroke

The Ryobi WYL is the same way, small brass jet that is held in by a tiny "O"ring.

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