Ryobi problem
 

I have a frustrating problem with a Ryobi 31cc conversion. It ran great when it was a weedwhacker, but now it's almost impossiple to get it to run. It'll run on the prime but doesn't draw fuel through the feed line. I choke the carb with my finger and crank the prop through like I usually do before starting and no fuel draws through. I've checked everything many times, changed gaskets, used gasket sealer and taken the carb apart to check for clogs, etc. Nothing helps. It's not the fuel tank, because I ran another engine the same day using the same tank. Could it be a problem with the reed valve, or what?

Ryobi problem
 

When you converted the engine from its former life what did you do about the priming bulb fitting?Some people retain the bulb but if you didnt the fitting on the carb must be plugged....As a weeder the engine uses a cheap rotating plate choke.....why didnt you retain it?It sure makes life easier than sticking your thumb in the carb.....

Ryobi problem
 

Yes, I did plug the other fitting. I crimped the end of it and soldered the opening to make sure there was no air leak. When I disassembled the carb after trying to run the engine, I didn't see any gas inside at all. It was dry. Maybe I should have kept the choke, but I don't think that's the problem. It doesn't draw fuel even when it's running on the prime.

Ryobi problem
 

Captinjohn,
How can you tell if the reed valve is good or not? And where can I get Walbro carbs? This Ryobi has a Zama carbureter, made in China, which looks like a copy of the Walbro, which has made in Mexico stamped on the bottom.

Ryobi problem
 

There,s a pulse hole in the crankcase where the carb bolts on. Make sure the hole in the plastic block lines up with this. Also make sure the hole lines on the other side of the plastic block lines up with the hole in the carb

I flunked my kamikazi pilots licence test !!

Ryobi problem
 

I finally got it to draw fuel by taking the covers off the carb and wetting everything inside with gas. I actually got it to run for a while, but when I shut it off, I couldn't get it to start again. I tried to keep the pulse hole lined up, but maybe the reed valve isn't closing completely. The compression is awfully low. Would increasing the compression make it easier to start?

Ryobi problem
 

This engine is a low compression engine. It will gain compression when it runs (oil / gas).

You can replace the thick head gasget with a thinner one, but the gain is very small. The up side of this lower compression engine is you can start with a typical glow started. The big upsided is the cost is about 100 bucks converted.

The Zama carby locks up when dry. Bummer you took the primer bulb off. I have one that does exaclty what you are seeing.... just pour a bit of gas on the vent side of the diapham and you should start pumping again.

Ryobi problem
 

It's frustrating. I got it to run for about 10 min straight. Nice and smooth with good transition from low to high throttle, but when I shut it off and tried to restart, it wouldn't pop or anything.
I wanted to use this engine on my 1/4 scale Tigermoth because of the narrow cowling, if only I could get it to start reliably. I have Homelites in other planes and they start real easy, but you have to cut a big hole in the cowling for the carb if it's a narrow nose.

Ryobi problem
 

Captinjohn,
Engine was not hot. I ran it in 50 degree weather and I could touch the engine afterwards. I am hand flipping and using 32:1 gas, but it's been tried with a heavy duty starter with the same result. Your method of checking for leaks sounds good. I'll try it.
I just test ran a G62 right out of the box and it started so easy I felt like kissing it.

Ryobi problem
 

Open the reed valve stop, so it allows the valve to open twice the amount of the stock setting. (i think 1/8')

Ryobi problem
 

captinjack:
You don't need a better reed valve. If you havn't opened it yet then try it, you can always close it back to stock.
When I first tried my Ryobi, it was stock except for the carb. (the throat had been opened (easier to get a bigger carb).
I couldn't keep the engine running without choking it. After bending the valve stop, so it would open wider, the engine came alive and ran great.

Starting
 

There is a chance that your problem is not gas but spark. Losen the mag screws and set it as close as you can to the flywheel without it rubbing anyplace. This will give you spark at a lower speed.

Ryobi problem
 

I'll try that. Thanks

ryobi
 

Hey Guys! I convert homelights & ryobis and it sounds like to me that the carb might need a new diaphram on the pump side ( opposite the primer bulb). I could be wrong but every time I've had this kind of fuel problem thats where I start. If Im not mistaken , when you take the cap off the pump side the diaphram goes on the carb between the gasket and cap, if this is not correct the engine will starve. If you do get the engine running (pour gas in it) Vacuum from the cylinder is enough to keep it running. I know that if I go to an over size carb on these engines I put the diaphram on then the gasket & it usualy cuts the fuel down enough to keep it from flooding out & running rich. For the correct reed setting you should be able to get a 1/8 drill rod between the reed & reed stop. Hope I,ve helped.

Steve

Ryobi problem
 

I opened the reed valve to about 1/8 in. I got it running for 10 min. straight with occasional goosing of the throttle and tweeking of the mixture. It ran fine, but when I shut it off I coudn't restart after a half hour of flipping and choking and flipping, etc. No pop or anything. I gave up and went to bed. Maybe I'll try again this weekend when my arm gets better.

Ryobi problem
 

If the reed valves are sprung, the engine will only pop when brought past a compression stroke. It will not run on it's own.

Jim

reed valve
 

I'd been having trouble with my Ryobi conversion for the past month, it would run great for ten to twenty seconds, then start 4-cyclying. No amount of carb adjusting seemed to help, tried a different carb, still doing it. Then I remembered that I had opened the reed valve limiter a little. Close examination revealed that the reed was not completely closing any more. I rebent the reed limiter and it cured the problem. So if you've bent the reed limiter, view it from the side while holding it up to a light to make sure that your reed is closing completely. If it's not closing, hammer the section that holds the base of the reed flat, reassemble and check to make sure the reed is completely closed.

Ryobi problem
 

Thanks,
This sounds like a good thing to check. The reed valve was one of the things I've been suspecting.

Ryobi problem
 

Put an automotive compression tester on it , if less than 75 lbs your wasting your time. Riobi is the lowest on the totem pole as far as quality goes. Irepair small motors for a living.

Ryobi problem
 

Maybe that's the problem. I've had much better luck with Homelite conversions. The Ryobis, with the rear carb & exhaust, would be ideal for narrow cowled planes like the Chipmunk or Tigermoth. if only they were more reliable.

Ryobi problem
 

I've converted many Homelites, no problems. Homelite Super Mini, 30cc makes a nice conversion as the carb sits upright beside the cylinder for a narrow profile.

Ryobi problem
 

I ended up using a Homelite 30cc on the Tigermoth. It flies the plane fine, but the carb sticks out quite a bit through the side of the cowl. It kind of ruins the looks of the plane on one side.
I never heard of the Super mini. What does this come in?

Ryobi problem
 

CaptinJohn

The Super Mini is an older Homelite from the 80s. Ihave a digital camera but can't get it to cooperate with the computer. I also have an old Super XL Homelite. 60cc on a Byron Christen Eagle. It has an old Tillotson carb with a diaphram accelerator pump on the side of it. Idles with complete 2 cycle all the time.

Ryobi problem
 

I pulled the plug out of the Ryobi last night and tested the spark. It was very inconsistant. I narrowed the gap a little and got a consistant spark even when flipping slow. I also pulled the backplate off and looked at the reed valve from the side, and sure enough it wasn't sealing. I could see light through the space. I tried to run it and got consistant popping but no run. It acts like it wants to run, but I think I'll have to play with the reed valve more, and my mixtures might be out of whack from all my past efforts.
Thanks to everybody for their ideas. I think I'm getting closer now to getting this thing to run properly. I'm on a mission now.

Ryobi
 

Instead of bending the reed valve, see if you can just turn it over.

Ryobi problem
 

tkg,
I wasn't planning on bending the reed valve, just the base of the limiter bracket so it presses the base of the reed valve down better. Hopefully, that will do it. Is the reed valve supposed to have a curve in it? Right now, when I remove it, it's flat.

Ryobi problem
 

The reevalve should be flat. Also if there is a small gap at the end of the reedvalve don't worry about it. When the piston is on its downstroke, crankcase pressure pushes the valve closed.

Ryobi problem
 

The phelan coil on the Ryobi is rather weak in the spark department anyway. you will be lucky to get a blue spark from it. You will have to keep your plug gap correct @ .020" and the coil as close to the flyweel as possible without it actually touching.

TK
The 32 McColloch piston and cylinder I got from you guys works really nice. It makes a whole lot more RPM than my Stock one. The one from you was cut down at the base.

Good luck

Jim

Ryobi problem
 

Get the fuji 32 thats what i"am using on my 1/4 scale tigermoth
Then you won't have the problem your having. it fits real nice in side the narrow cowl.

Ryobi problem
 

Ron45,
The fuji looks interesting. Does the carb stick out through the cowl on your moth? If I have to have the carb sticking out, I'll leave the homelite in. It's been very reliable and flies the plane well. Also, what 1/4 scale moth do you have?

Thanks,
Jim

Ryobi problem
 

Yes < it sticks out a little, I got my tigermoth from someone else and they had the cowl already cut. I didn't like it, thats why I went with the fuji 32. It fills the cut that was there nicely.Being a plastic cowl i realy couldn't fix it and I was never told who made the kit. So I did the next best thing I could do. FILL THE HOLE.

Ryobi problem
 

Here's a picture of the Tigermoth in question. Maybe I'm being too picky, but after all the time I spent detailing it, I really hated to have to cut a hole in the cowl. The Ryobi would be such a nice fit.

Ryobi problem
 

From what I can see you done a real nice job on it. As soon as i can (saturday) I'll put mine together and send you a side view and a front view so you can see how little the carb shows. OK

Ryobi problem
 

I got the Ryobi running last night, after only a little bit of choking, and it ran fine. I adjusted the needles a little to get a good idle and good transition to high speed. The thing is, when I stopped it and tried to restart...Nothing. No pop or anything. I checked the spark, and didn't get any. Just intermittant. I'm wondering now if something is happening to the coil when it gets hot.

Ryobi problem
 

The coil on the Ryobi is rather weak to begin with. You have to have the plug gapped at .020" and the coil about .010" or less but don't let it hit the flywheel.

Then wait till there is a night with no moon. ;) Take the plug out and fasten it to the motor on the out side where you can see the electrodes. Then spin the motor over with an electric starter. You will see a little short duration yellow spark come out of it. You will unlikely ever be able to see anything by turning it over by hand.

It is really not that unusual for a coil to go bad. You'll need another to try on it if you are not getting any spark. I had a Walbro go bad on a Homelite. It would make a spark in the above situation but was intermittant when running. New coils are expensive at around $40.

The Walbro coils are a lot hotter if you could find one that would fit. Don't know that they ever came on a Ryobi though.

If your looking for another junk Ryobi engine to steal a coil from, don't forget that there are other names on those. Lawn Boy, Ryan, Sears, Toro, and others. Some Ryobi coils have RPM limiters in them that won't let the engine run much more than 7,000.

Good luck,

Jim

Ryobi problem
 

Jim,
Thanks for the help and suggestions. I'll have to start looking for something to rob a coil from and try it out.

Jim