Ryobi 31cc engine setup
 

Hello all,

Recently I converted a Ryobi 31cc using WackerEngine parts and now Im at the point where Im about to mount it to my plane, a Cap 231EX. Now, this is my first gas engine and I have a few questions on how I go about setting up the tank and tuning it. I know this topice probably would have been better suited in the general gas forum, but because this IS an converted engine, I know a few of you would probably be more helpful here.

So my first question is how do I set up the entire fuel system? I have the tank that came with the plane, besides replacing the fuel lines to gas lines, will this tank work our should I replace it completely (it was suggested that a 1.20-1.50 glow engine be fitted for this plane)? Which nipples on the Carb. go to which line and where do those lines go? Ive read about "looping" the fuel line, but how exactially do I do that?

Also, about tuning the engine, how exactially do the high and low speed needle valves need to be adjusted? I know from glow experience that you adjust the low speed untill it hesitates or dies on throttle up, then open in a bit from there, is this the same with gas? I know Ive seen suggestions that the plug be replaced and I currently have the "stock" plug in right now, which one should I switch it out with?

Thanks in advance for the help! After I recieve answers, Ill try and set it up and take pictures to let you all see if Im doing it right, or horribly wrong...

Colin C

RE: Ryobi 31cc engine setup
 

Predator,
The fuel input nipple is usually the one closest to the aluminum pump cover on the carb. The steel cover is the regulator. The other port is for the primer bulb, which must be plugged or capped, if not plumbed to the tank. Here is a great website with most of the answers to your questions.

http://www.geistware.com/rcmodeling/glowpower/gas.htm

Dave

RE: Ryobi 31cc engine setup
 

the fuel tank will work fine, but you need to go to your hobby shop or tower or whatever and get a conversion stopper for it, the ones for gas are generally redish, glow are usually black or white or something, they're somewhat universal, close enough to work anyway... for fuel line I'd go to a hardware store and get some small clear nylon hose, I got it for like $.15 a foot... most places want like $4.50 a foot for the right stuff... the nylon gets a bit hard after fuel has sat in it, but it is fine for general fuel lines, just use a chunk of the fuel line that came with the trimmer in the tank from the clunk to the stopper... that's the easiest way I've found, and wrap some type of hard wire around the junctions to keep it together. and about looping the fuel line, that's simple, it's for the vent line (you only need 2 lines, one vent and one supply, they have a pumper carb so it doesn't need exhaust pressure), for the vent line take it and wrap it around the fuel tank or around the fuel tank area, whatever works easy... and stick the line out the bottom of the plane somewhere, I just stuck mine through a hole in the firewall and out a hole in the cowl and zip tied it to the landing gear... but mine is still in the test stages and the engine is off for modification that I'll get to eventually... needs more power

as for the spark plug, if the stock plug says RD or RC on it, it's good, if it doesn't, you need one that does (if you have more weedie's or chainsaws in the garage, scrounge around, many come with them stock). I went one step further and stripped some coax cable of it's insulation and took the outer mesh wire and put it over the spark plug wire and grounded it at the mag, I don't know how much that helped, but it didn't hurt, plus it looks nifty :)

RE: Ryobi 31cc engine setup
 

Thanks a lot for the responses and help so far! Im going to run to Home Depot tonight and pick up some nylon line like you suggested, rangerfredbob, and try to set up the tank like you said. I wasnt sure about Dave's comment, but are you supposed to cap the vent line? Im not so sure you are, maybe I just read your answer wrong.

Now, only one problem I forgot to mention is that when I bought this engine, it was the engine ONLY and it was missing a few parts, including the entire choke assembly. Ive been looking everywhere for Walbro carb parts but cant seem to find a choke assembly for them. Does anyone know where to pick one of these up, or is building a custom choke my only option? I know these engines basically NEED to be started with atleast half choke on, and sticking my finger on it isnt exactially the smartest idea! I did just place a bid for an engine on eBay, but I would be in the same boat if I decided to convert that one too.

Thanks again guys, look for some pictures later!

Colin C

RE: Ryobi 31cc engine setup
 

Dave is refering to the carbuerator, there's two ports on it, one is supply, the other is the return line if you run a primer bulb, when the carbuerator is primed it will just cycle the extra fuel back to the tank through the other line, but if you're not using a primer bulb, you need to cap off the other line, a short chunk of fuel line with a screw in the end works fine.

I don't know if home depot has the nylon line in bulk like Ace does (or at least mine does), check out the weedeater parts area, they sometimes have a package with a few feet of the stuff for a couple bucks... I think I ended up using around 3 feet for my plane... but check if they have bulk hose first. for the clunk line, check a hobby shop to see if they cary any tygon line, if that fails, try the mower shop, you'll only need a few inches, but don't even try to use the nylon for the clunk line, it's too stiff after sitting in fuel.

as for the choke, the stock choke on the ryobi's is a simple piece of sheet metal that pivots on one of the carb bolts and covers the carb opening, I've heard of some people cutting a super ball (bouncy ball from the quarter machines in the grocery store...) in half and gluing it to a toungue depresser and using that for a choke... on planes they don't really have to run on part choke to stay running if you stay on the throttle and run them up before take off, the prop puts enough load on them to warm them up quick enough... a choke doesn't have to be all that complicated...

RE: Ryobi 31cc engine setup
 

Another good way to start a gas 2 cycle engine is to give it a shot of pre-mixed fuel from a prime bottle. Prime with trottle wide open ...then place throttle back to idle and flip start or electric start it. Let it warm up good and then advancethe throttle. A shot of engine starting fluid works good too. Good Luck Capt,n;)

RE: Ryobi 31cc engine setup
 

Okay now Im a tad bit confused, let me just make sure Im thinking straight.

On the tank, one line goes to the carb as the supply line. The other line which on a glow engine would go to the muffler, wraps around the tank a few times and comes out of the firewall and is left alone. The other nipple on the carb is the return line, which is to be plugged if not using a primer bulb, but if a primer bulb is being used, should return to the tank. Is that correct?

Sorry that Im not all that gasser savy yet, but Im trying. Thanks for the help again!

Colin C

RE: Ryobi 31cc engine setup
 

So if I did this, the engine would not need the choke plate at all? It sounds like a good idea, but would this work easily in a coweled airplane? I am a little hesitant about placing another servo to control the choke, with interferience and all. When I get the engine fully installed, Ill try this, even if I do end up getting a choke for it.

Sorry for the double post.

Colin C

RE: Ryobi 31cc engine setup
 

predator500: Hey in Florida you should not need a choke. A cowled in engine should be easy to prime. That small dia red tip on a can of starting fluid or attached to a prime botle should go in the any tiny hole. Regards....Capt,n

RE: Ryobi 31cc engine setup
 

^Haha its true, hardly ever does it get below 50 down here during the winter! Yeah Ive looked all day for that choke assembly, and its nowhere to be found. Oh well, I guess Ill just prime it like you said. Thanks for the help guys.

Colin C

RE: Ryobi 31cc engine setup
 

most people use a wire sticking out of the bottom of the cowl to choke, the wire is connected to the choke lever, pull the wire down and it's choked, push it back up the choke is off... doesn't need to be servo controlled...

as for the fuel tank vent line, one wrap is enough, and if you don't flip it over durring transportation with gas in the tank, it doesn't really need any wraps... and yes, it's vented to the atmosphere... just left open, you have to get air into the fuel tank to displace the used fuel... that's it's only purpose...

RE: Ryobi 31cc engine setup
 

I really don't recommend starting fluid for two stroke engines. It is extremely dry, and offers no lubrication. It actually washes any residual oil off, making it even worse. WD-40 used to work, but I don't believe it is flammable any more. Starting fluid can damage a two stroke though, so figure out a choke.

AV8TOR

RE: Ryobi 31cc engine setup
 

^Would you also not suggest spraying pre mixed fuel into the carb either?

Colin C

RE: Ryobi 31cc engine setup
 

you can use a primer bulb or whatever to inject gas mix into the carb with no problem.but if you would like send me your snail mail addy through a PM or email and ill send you a ryobi choke i found in my collection of conversion parts for free.im not going to use it.

RE: Ryobi 31cc engine setup
 

A shot of premix prime won't hurt anything, but it's easy to flood the engine. A choke really is best.

AV8TOR

RE: Ryobi 31cc engine setup
 

I will GLADLY take you up on that offer! I really appreciate this, thanks a lot! Look for a PM tomorrow sometime...
^Well as you can see, my problems are solved for the choke problem, but thanks for your help!

Colin C

RE: Ryobi 31cc engine setup
 

Av8tor,
WD40 still burns. I use it a post run oil in my glow engines, and have actually ran engines on it (with a battery connected to the glow plug). I have had several people tell me that WD40 is bad for my glow engines, but I have been using it since 1990 and have had no problms. I think you could use it to prime a trimmer engine.

RE: Ryobi 31cc engine setup
 

Glad to know that it still burns. Seems like I heard that it wouldn't, and tried some and it didn't a good while back. Maybe they changed the formulation or propellant back to the original...

Personally I wouldn't use it as an after run, as it will eventually evaporate or dry up and leave the engine without protection if left in an engine that sits for a long time. I use automatic transmission fluid as an after run oil in all mine. I've had some of my engines sit for years, and later fuel them up and away they go like new. I have several engines that are 30 years old that have had that treatment since new, and still run like new. (Never been rebuilt either!)

Incidentally for all the Gas/Glow engine users, I treat all my Gas/Glow engines just like glow engines: I run them out completely dry after flying, and then use ATF as an after run oil. The methanol and nitro in the Gas/Glow mix will cause corrosion problems just like in glow engines; perhaps worse because of the needle bearings on the crank/rod in "Gas" engines.

AV8TOR

RE: Ryobi 31cc engine setup
 

I sent you a PM earlier today with my adress, let me know if you didnt get it (my sent box is empty, odd).

Well a little update, I went to Home Depot and bought some actual gas line, at $2.57 for two feet, ugh. So now I have 4 feet of line to mess with, which is good. Im going to run to the hobby shop tomorrow and pick up a gas stopper for the tank, then hopefully once I find someone with a drill press, Ill begin to mount everything.

Thanks for all your help guys!

Colin C

RE: Ryobi 31cc engine setup
 

Just a little update......I picked up some gasket material and fitted the backplate and the head/crank case gaps with new gaskets. The engine is 95% ready to go, just need to get the choke plate and cut it down to fit. Also, I picked up an engine off of an old wacker for future use. Its a Poulan Weedeater GTi 16, but I have absolutly NO idea what kind or size engine this is, any ideas? The engine turns over nicley, the carb is Walbro and looks very clean but is missing a high end needle valve, but its a "short shaft" engine so I dont know if that would be a varying factor. Well if you have any ideas as to what it may be, let me know! Thanks and happy holidays.....

Colin C

RE: Ryobi 31cc engine setup
 

From post #3

I would not use silicone line(THAT CAME WITH THE PLANE), for a clunk line with GASOLINE. Just asking for problem.

Black neoprene line will work for clunk.

I like the primer bulb and extra line from carb back to the tank. Why?
1) well it does not look like it belongs on a plane. Do I care?
2) you need a good choke seal to pull fuel from tank while turning the engine over to prime.
The primer bulb fills the carb in a couple of seconds no muss no fuss.
3) save having to pinch and solder seal that fitting on carb;
4) you can plumb a 'T' fitting between the carb and tank and use it as a fill line/drain line for the tank (PUT THE "T" BETWEEN THE PRIMMER BULB AND FUEL TANK NO RESTRICTION TO FILLING FLOW IF VENT LINE IS OPEN, NO CARB FLOODING;
5) any fill fitting (FUELING VALVE GAS RATED about $13 USD transfered from your pocket ot someone elses) you put between the tank and inlet fitting to carb adds a minimum of 3, possibly MORE locations for air to enter the line and cause problems!
6) see #1

7) the stock carb on the weedies are fairly small in venturi size and many times get upgraded to
an 11mm venturi. Walbro 167-a is a good upgrade and it has an intergal primer. Available for many locations
including DDM online.

See #1

Spraying other combustables into throat does not fill the interior passages of the carb and that is really on of the main things your after in starting sequence.
.

RE: Ryobi 31cc engine setup
 

I think I was getting at using the clunk that came with the tank, along with the tygon line that came with the trimmer engine inside the tank... but he didn't get any of the stock fuel line, so it doesn't matter anyway...

RE: Ryobi 31cc engine setup
 

^Actuially in the engine I picked up, it was a full wacker so I got some fuel line and a clunk out of the tank, Ill definitely use that now.

^^And the only problem with that is I actuially do care if lines are hanging out of my plane! BUT! My engine will be coweled and run inverted, so I dont think those lines will be visable at all! Ill have to get a T fitting like you said, but that shouldent be too hard of a piece to find at an auto parts or hardware store.

Like I just said, I plan on running this engine inverted, is that going to be a problem? The wacker I got it off of ran it inverted, so I dont see how it would be a problem, but I'd rather be safe then sorry.

Colin C

RE: Ryobi 31cc engine setup
 

the poulan weedie is going to be a poulan engine, probably a 25...

RE: Ryobi 31cc engine setup
 

^Yeah after looking over it a little bit, I can see Poulan written on the flywheel. I did think it looked a bit smaller then my Ryobi, but hey all that means is I have another engine to throw on another plane (eventuially)! Ill start working on that when Im completely finished with my current project.

Colin C