Another Ryobi Question.
 

I am trying to tear down a Ryobi 31 for conversion and have a dumb question or two. First, How do I get the clutch off? There is an arrow and the word "OFF". Is it threaded or pressed on? Second, Does anyone make a crankcase cover oother than te plastic one? And last, This looks like a long shaft engine. Is it worth converting or should I find a short shaft version?

Thanks,

RE: Another Ryobi Question.
 

Roger,
In the hole that the trimmer drive shaft goes in has a screw inside. Use a allen wrench to remove the screw and the clutch drum will slide off. The clutch shoe assembly has a normal rifhthand thread. The backplate is fine. Just carefully trim it without cutting into the gasket seal area. Trim away the various bumps on the back side. Use washers if necessary to allow the mount to seat level. Long shaft is fine. The prop hub will slip over the shaft, no threads. The prop nut hols it all together. Do a search for ryobi conversion.

Dave

RE: Another Ryobi Question.
 

Dave, Right, I found the screw and removed the drum. Is there a good method for holding the shaft while I unscrew the shoe? I dont' want to gall the shaft. This is my first conversion and I am really leary about breaking stuff. While I have you here I would like to know if the standard ignition is ok or do I need to drop another 100 bucks or so on an after market system. I'm on a limited budget which is why I'm covertig rather than buying.

Thanks for the info.

RE: Another Ryobi Question.
 

Roger,just put a large screw driver or punch in the lower part of the flywheel fins and brace against engine and use a small hammer and give the clutch a small tap on the side and it should come off.if theres a nut there hold it the same way and use a socket and racthet.check this site out for inexpensive parts though theres a lot out there.
www.macs-rc.com

RE: Another Ryobi Question.
 

Clamp the flywheel lightly in a vise and turn off the clutch with a pair of channel lock pliers. Use a gear puller to remove the flywheel or pry it frmm side to side with a large flat screw driver. The mag ignition is fine. Careful not to loose the key if it is not cast into the wheel. Buy a longshaft kit from Wackerengines.com. Buy a resister plug at your auto parts store.


Dave

RE: Another Ryobi Question.
 

Thanks for the info Dave. I was hoping there was a way do get the clutch off befor I had to hack off the shroud. It looks like the clutch is the last thing added to the engine befor it is added to the cutter shaft. I guess I will just put a drummel to the plastic shroud and expose the flywheel. When I get it torn down I'll be back for help with the set-up. I will need some help with the carb as it's continuing failure is the reason this weed eater is going to be an airplane. The guy who fixed it last time said that the walbro carbs only last about a year. It lasted one day this time. After trying to start it for abot a half an hour with only one quicq run I nearly tossed the whole thing into the back of the pickup for the next dump run. But I can always use a gasser so I will convert it and try to find a better carb.

RE: Another Ryobi Question.
 

An airplane engine really does need to be easy to start.

I don’t agree with your mechanic. Carburetors don’t really wear out but they do get dirty from time to time. Pumper carbs are extremely susceptible to trash accumulating in a brass screen in the carb. In addition it is almost impossible to avoid some trash when transferring fuel from pump to can and then to airplane or weed eater. The clunk filters used in weed eaters are good but they also need replacing occasionally.

To be successful you will likely need to learn to service and clean the carburetor.

Bill

RE: Another Ryobi Question.
 

Bill, will I need to learn the carb by trial and error or is there a book on them out there? This engine used to start on the first pull but this year it would hardly run. One shot of starting fluid and it would start, only to die when the either was gone. I know I have a fuel problem but with the machine assembled finding it was very tough. at least now the system will be exposed and a lot easier to work on. This motor may be my learning test bed. with all the parts out on the bench it should be a lot easier to clean and troubleshoot.
Any info on the system will be appreciated.
P.S. Will I need to retain the primer bulb for an airplane setup? I cant' remember seeing one on any of the pictures I have see here and there.

RE: Another Ryobi Question.
 

Thanks all, I got it torn down. The clutch spun off with a few hammer taps and the flywheel popped right off. So now I have a few more questions.
1. Do I need to cut off the end of the crankshaft that is threaded inside?
2. How? Hacksaw or cutoff wheel?
3. How do you remove the starter pawls on the flywheel?
4. My muffler is the type that is held on by springs, will the aftermarket mufflers (whacker etal) work? The cyl. has no bosses for muffler screws only 3 cast in pins.
5. Is it worth it to have the flywheel turned?

Ok that will do for now. I must add that I have gotten the conversion instructions offered by Whacker Engines and while the are very helpful there are a few gaps that I hope you all can fill in for me. Your help has been great and I am sure that without it I would have broken something.

RE: Another Ryobi Question.
 

Hello Wascamp,
Place the flywheel with the pawls facing over a slightly open vise. Using a thin punch locate the pawl pin positions and drive them out with a hammer. The trimming of the flywheel saves a little weight and requires balancing of the wheel. Use a good prop balancer or send it to a shop, such as wacker etc. The internally threaded end of the shaft can be retain to mount a spinner later. You can cut it off with a dremel or hack saw. Springs to hold the muffler are not good, but will work. It reduces your choices of after market mufflers.

Dave

RE: Another Ryobi Question.
 

Thanks for the info Dave. I looked on the back of the flywheel and it looks like the pins do not go all the way through. They are steel and I cant' see any change of "color" in the area where they are located. I hate to think what might happen if I tried bump them out with a chisel. I might get a bite with vise grips and try to twist them out. I have been warned not to damage the flywheel as it is the most expensive part on the engine.

Thanks again fo the help.

RE: Another Ryobi Question.
 

Hello Wescamp,
Some time the holes for the pins aren't drill through completely. You can drill a small hole from the rear or break through the thin aluminum shell with a punch. A chissel isn't a good idea. Ryobi's that are considered beyond repair are always available a local repair shops. If you send the wheel off, the pins will be removed when returned.

Dave

RE: Another Ryobi Question.
 

Roger,

Sorry I don’t know of a book but there probably is one. I left the primer bulb and choke on my engine. WD 40 also works as a starting fluid.

When an engine runs until the prime is gone the problem is usually fuel delivery. Tank clunk filter and brass screen (smaller than a dime) in the carb seem to be the first places to catch the trash. I usually clean, reassemble and try again and most of the time the problem disappears.

The carburetor is mechanically quite simple but its impossible to figure out the purpose of all the cross passages. Additionally offending trash is usually disturbed during disassemble and not seen. The muffler and air box add complexity in two strokes. Both affect the overall carburetor operation and changing either will often change the carburetor operation sometimes in strange ways. The air box and muffler were left on my engine so experiments could be made one component at a time. Would have left the pull start on but it did not appear possible.

Good luck.

Bill

RE: Another Ryobi Question.
 

BillS, I yahood Walbro and found an article in a model boat publication that details the rebuild and setup of the carb. It will be a usefull guide to get me started.
When I removed the muffler I found that it had failed where it was dimpled so the exahust was leaking out. I dont' know if that would effect the engine or not but I will need a new muffler before I start her again. The exahust port on this engine is round rather than rectanglular and most of the aftermarket mufflers for the Ryobi are of the rectangular style. It seems to me that there is a lot of variation in these engines. This one is about two years old and looks very different in several places from what I have seen and what has been discribed by others. Do you know if the 14mm bore carb is a standard or did I get an oddball carb as well? I dont' have it in my hand so I cant' give you any numbers, but it is a walbro, mexican made, and it looks like the ones shown on the converion sites I have visited.

RE: Another Ryobi Question.
 

Roger,

Glad you found a repair article. Small exhaust leaks don’t affect performance to a large degree.

My Ryobi is a long shaft purchased new this spring as a weed eater for $60 or so. Tomorrow I will measure the carb and get pictures of the exhaust port.

Bill

RE: Another Ryobi Question.
 

Roger,

The markings on the carb are:
ZAMA China
ZAMA 3
P22
3YA

The throat measures .325” and will be about 8.3mm.

The exhaust port is rectangular and .330/. 340 inches high by .990” wide.

Hope the information helps.

Bill

RE: Another Ryobi Question.
 

Bill, Mine is definatly a walbbro of 14 MM bore. I found a site that has part at discount , a new OEM muffler is $6.70 and a gasket set is $3.60. There may be cheaper places but I have a starting point, price wise. Whacker has the big bore carb for $30.00 if I need to replace the one I have. Right now I am trimming the carb/crankcase plate and will start grinding the forward flange to contour. I will have to build an engine test stand as I dont have a plane built yet to put the engine on. Does anyone have plans for one or can I just wing it. I've got lots of wood and screws laying around so it should not be a problem to knock one together.

Thanks for the Zama info. More later.

RE: Another Ryobi Question.
 

No, no plans that I know of for an engine stand. Some guys just "nail" them to a fence post. Just make sure you're on the opposite side of the fence from the bull...

AV8TOR

RE: Another Ryobi Question.
 

Hi!
Are you sure that you have a Ryobi engine? After reading through all of these posts some of the things you mention are not consistant with a regular Ryobi. Round exhaust port and muffler held on by a spring I have never seen on these engines. Is it possible you could post a couple of pictures? I am really quite courious about what it is you have. Thanks......farley9n

RE: Another Ryobi Question.
 

Your wish is my command. I have taken off the heavist part of the forward flange and trimmed the carb mount. I am pretty sure it a Ryobi as I bought the trimmer new and the box said Ryobi 31 CC. I used the Ryobi site to find the part number for the muffler and pulled up an assembly drawing that showed my engine. I think this is a cheap version made for the OEM trimmer makers. I just bought a Poulon Trimmer and it has the same engine. The part numbers match. Plus, it came apart exactly as I was told that it would which leads me to think we are on the right track. This is a single ring version and the barrel casting bears the number 028756. If it helps the flywheel was made in the USA.

I need to know how much more of the forward end I should remove. Should I take it down all the way back to the face of the block? I would leave some of the webs that support the forward main bearing and sealboss. The pictures I have seen show most of the belled area removed. It might be a pain to remove it all but I think I can get most of it off with the tools I have at hand, however I migh have to remove the barrel and piston to get it all. Any thoughts on this?

RE: Another Ryobi Question.
 

Thanks for the get back and the pictures. All I can say is WOW! What you have is what once was a 32cc Poulan/ Weedeater engine. They have been very similar for years with the Poulan perhaps being the better built but heavier of the two. Bigger bearings and crank pin with a real rod but smaller ports than the 31cc Ryobi"s. With all the merging and etc, that has been going on I can't keep up. The new Ryobi's are the old 30cc Homelite and so it goes......Just when I thought I knew it all!......Farley9n

RE: Another Ryobi Question.
 

Ryobi 31s were designed as "throw-away" engines, or so I'm told. It costs more to repair than they're worth. So, some sales & repair centers that get a customer looking to have a Ryobi-powered trimmer repaired, simply offer them a "trade-in" toward the purchase of a "better" unit. The trade-in gets tossed in the back. After they get a load of such "junk", they pay a hauler to cart them to the recycler. That is, unless I happen to come along:D. For free I'll cheerfully haul away these "junk" Ryobis to be recycled into model airplane engines! This plus yard sales can quickly provide you with a lifetime supply of engines, carbs, etc for a very small investment. Better hurry, though; it looks like these 2-strokes are being phased out.

RE: Another Ryobi Question.
 

EZFLY,
So are they throwaways, or not? My local small engine guy has a few in the junk pile that I might be able to have cheap. Is this version a keeper? If so, I can afford to build that FW Condor I have always wanted.

An update for all the guys that helped me with my questions: The engine has been completly stripped down and the case has been trimmed. I punched out the starter pawl pins per the hints and it was a snap. I need to find a few spare dollers before I order the prop hub and mount. The wifes car tossed a speed sensor and that ate up my engine money. There is really not a rush on this as there is no airplane for it yet. I build in the winter and work on the "Ranch" during the summer, so projects like this sort of gather dust untill "snow flies". Once I get it running this fall I will be back with some more dumb questions.

Thanks to all that helped out on this. I could not have done it without your kind help.

RE: Another Ryobi Question.
 

Hi,
I think what he ment was that they not worth the cost of labor to repair at $40.00 per hour. Our labor is free, so we can pick them up for little or nothing and have fun with them. The secret is to keep the investment low.

Dave

RE: Another Ryobi Question.
 

Dave,
That's no secret. It's a way of life. That's why I will sacrifice a little weight rather than spring for a new ignition setup. $ 150.00 will buy a lot of balsa and Koverite. You know I'm living close to the bone when a car repair blows my hobby money.

RE: Another Ryobi Question.
 

In addition to the cost of electronic ignition the dynamic balance of the engine is better when running magneto.

Bill

RE: Another Ryobi Question.
 

Hi Roger,
Dave is correct - they're only throwaways if you're paying $4o per hour labor. If you like these little engines and want to start a stash, as I have done, I have this advice: First, be wary of any engine that was stored outside, exposed to rain. It's not only what you'll see on the exterior, the muffler and bolt heads, for example; it's the corrosion that will most likely have formed on the inside that causes the mess. Unless you can trust the seller, you won't know until you do a tear-down. Yes, aluminum corrodes like crazy. Second, develop a haggler mindset. Be nice, but don't pay more that you have to. - EZFLY

RE: Another Ryobi Question.
 

EZFLY,
Thanks for the tips. I live in a rather remote area but I see old weedwhackers at yard sales from time to time. I think will try to start a cashe of them. We have one small engine guy in our quaint village (Pop. 750) so I might be able to pick up some from him on the cheap. Now all I need is a turret lathe and mill to make my own parts. Right!! I still plan on building a 1/4 scale Woodhopper ultralite for my weedee engine. It ought to perfect for an 8 foot span/15 inch chord clark Y wing.

RE: Another Ryobi Question.
 

Roger, IMO you've hit the bull's eye:). At one time, when I saw a Ryobi I said "EL YUK." Now that I'm retired on a "fixed " income I'm singing that tune in reverse: "KUYLE" as in cool. :D OK all you Ryobi enthusiasts, I've come clean; hope I'm forgiven!

As to my "throw-away" remark above (didn't I just say "I've come clean"- YIKES!), this has been covered several times before ( ck TKG of C-H Ignition, for example).

If you can, stay away from Ryobis that were exposed to rain. Moisture in the crankcase is bad news. Extent of corrosion depends on how long they've been wet.

Finally, to paraphrase Lucy (Peanuts): Don't take Ryobi conversions too seriously. :D Enjoy, EZFLY

RE: Another Ryobi Question.
 

Hi,

Roger- A turret lathe and a vertical mill...wow, I only wish. ;) Some years back, lots of local shops went bust during the Rust Belt era, and you could pick up a Bridgeport for well under $1500.

Another embareassing(sic) revelation: My initial exposure to RCU was mainly in the BUY/SELL areas. So when I decided to become a "motorhead" and do some conversions I didn't check the FORUMs first. After joining-in recently and becomming a Member, THEN I checked these Ryobi threads! Boy did I ever reinvent the wheel! [:o] But, ya know, I'm really enjoying the experience. I don't think I'll ever be a "real" motorhead, but I sorta FEEL like one. :) Some of the guys told me that "you can't do this kind of work without a bunch of machinery." True, I sent the flywheels out, but everything else was done with simple hand tools, a drillpress, and a dinky little Unimat lathe. It's amazing what can be accomplished when the mind is in gear. (I guess that makes me a "gearhead" too!!) :D

Sorry for all the "chatter," guess it comes with the territory. For a real dose, search "Al Kretz." Zowwee Diggins! That's REALLY a chatty thread!

Enjoy your Ryobis. EZFLY

RE: Another Ryobi Question.
 

EZYFLY,
Turret lathe? Vetical mill? Oh, if only! I doubt that there are any of them in the entire county. As a Tool and Production planner at a large Airplane manufactrer up here in the Northwest I wrote manufactruing plans for airplane parts and tools. How about a five axis NC mill? That thing could make an engine out of one billet. My own shop is more primitive. I use a belt sander. drillpress, drummel tool, bench grinder, hacksaw, and several sizes of hammers! I cant' make prop hubs but I can make flat parts bend things. I need Santa to bring me a gas welding setup and I will be set.

Once I get a prop on her I can set up my test cell and get her tuned up. I still dont' have an airplane that I can use but that will come. Perhaps a giant pink foamy.

RE: Another Ryobi Question.
 

I have been reading these postings on Ryobi Engines. Didn't know it but the ones I have been fooling with for years, some of them are Ryobi. I recently have stumbled onto a supply made by Mtd. I am a vendor who works at Lowes. If they get any rejects back MTD will credit them and the RTM clerk just throws them away. I have talked to the store manager about buying the engines off these trimmers. The downside to this is these crankcases are cast in such a way that you must grind the metal shroud from around the fly-wheel. I've always stuck to the engines that are not rear induction. Will these really turn up and put out good power? These are 31cc engines.
Mike

RE: Another Ryobi Question.
 

HI,
The Ryobi is the most conversion for airplanes. The Homelite is also very popular, but you do have to trim the flange from the case. The amount of power produced is dependent on a few factors, such as carb size, muffler and cylinder configuration. Some engines have curves cast above the transfer ports to ease starting. These reduce power output. The two ring ring engines seem to be best. Most of the parts are interchangable, so you can mix and match for best configuration.

Dave

RE: Another Ryobi Question.
 

joemyke,

The Ryobis with a two-piece crankcase are much easier to convert, but the ones with integral flywheel shrouds can be cleaned up nicely. It seems that the more-recent production runs used the one-piece casting. Such is progress![>:] Either way, once you get the hang of converting these engines, it goes quickly, with only minor metal work. You don't need a machine shop!

As you may have seen in my earlier posts, I'm all for accumulating a bunch of these engines; it's basically the only way you're going to get parts. True, Ryobis shouldn't be referred to as "high-perfomance" or "high-power" engines, but I prefer to stay well clear of the 18-8 prop on a running Ryobi!;) So, considering the dollars involved, Ryobis have plenty power and they perform quite well too. It all depends on what you want to fly and the kind of flying you want to do.

EZFLY

RE: Another Ryobi Question.
 

Purchasing individual parts for one of the these will cost you more than the initial outlay. Its best to have some spares on hand. When you consider that a coil costs $40 or a flywhell costs $40 or a carb cost $40.

I got a Mac 32 out of the trash about a month ago. There was nothing wrong with it. I use it to whack the weeds around the house. I already have a couple of converted Macs.

RE: Another Ryobi Question.
 

Just picked up a few more Ryobis. All are two-piece crankcases.:) Thought they were all going to be junkers for parts, but all except one is OK. I'll have to say that not every engine with signs of corrosion on the outside is bad on the inside, but be careful or bid down the price. It seems like most guys don't want to bother with the one-piece cases, but it looks like there are still a load of two-piece cases out there.