RE: Help with 31cc Ryobi conversion
 

Hi Guys: Just modified a 26CC homelite. The problem I am getting is low RPM's...only 5,400 witna 17X8 prop. I am testing with the stock muffler. Does this may be the reason for low RPM's? Thanks

Note: I installed a CDI ignition on it and timming seems to be right.

RE: Help with 31cc Ryobi conversion
 

Just an update on my Ryobi 31cc conversion. I worked on the reed valve and got it to seal off. I took and modified the original muffler. I removed the tube from inside the muffler and removed the little exhaust deflector. I drilled a 3/8" hole inside the muffler at the muffler inlet. I wanted to open the muffler as much as I can. I welded a 1/2" ID x 5/8" OD 3" long outlet tube. I pit the thing together with the modified muffler and ran it. I have a 16X8 Zinger Pro prop installed. I got about 7200 rpm and can now get the idle down to around 1900 rpm. I installed the muffler and blew into the exhaust to check for leaks as some said this could have been causing my high idle problem. The thing was sealed tight. This darn thing runs pretty sweet. Now to find a plane to put it in.
Thanks to everyone that helped.

RE: Help with 31cc Ryobi conversion
 

I think some engine react very different when run without a muffler. I took the muffler of my MB290 leaf blower to use on another MB290 on my test stand. Putting a muffler on the engine on test stand helped the idle on that one a lot. But my leaf blower now will not shut off and I need to choke it to kill it. Before it would idle lower than you could imagine. Bottom line...I think different engines can react very strange when removing the muffler!! Capt,n;)

RE: Help with 31cc Ryobi conversion
 

Take the muffler of and see if you get a RPM increase. You may have to retune the carby a touch! Capt,n P.S. Most engines run good at 28 degrees BTDC

RE: Help with 31cc Ryobi conversion
 

That's what I was trying to say a few posts back when the guys was struggling with run problems without a muffler... He didn't get it so I gave up.
Cheers,

RE: Help with 31cc Ryobi conversion
 

At the time I didn't have a muffler and didn't have the original modified yet. I have had other 2-strokers run just fine without a muffler. I didn't want to use the original muffler as it is a little heavy. I got the dimensions for a muffler from wackerengines and found it to be too big to fit in my application. This is why I ended up modifying the stock muffler. I was trying to do this conversion as low cost as possible to see how inexpensive it could be done.
I ended up buying a prop adapter and a Walbro WT-324 carb. I was given an ignition system. My total cost was $60. I didn't want to spend a lot of money if the thing wouldn't run right. I tried a Homelite conversion about 15 years ago and it was a disaster. I had to make parts for it. I used the flywheel and it shook violenly. I didn't want to repeat this again. So, not bad for a free wacker engine found in the trash.

RE: Help with 31cc Ryobi conversion
 

Madman, I have a Ryobi 31cc that I want to convert to ignition. Where did you get the prop adapter? Is your a short or long shaft? Thanks.

RE: Help with 31cc Ryobi conversion
 

I got the prop adapter with clamp on sensor from CH Ignitions. Mine is the short shaft. CH says they have the adapters for the long and short shaft engines. EI is the only way to go. Mine starts easy. Easier than my DA and DL engines. It starts right up even when hot.
http://www.ch-ignitions.com/#cat

RE: Help with 31cc Ryobi conversion
 

My question is...when you have a engine tunned real good without a muffler, then you place muffler on...how is the running of it then. I have found I always have to re-tune when having a muffler on engine...verses having the muffler off engine. What is findings on that? Capt,n

RE: Help with 31cc Ryobi conversion
 

I found the same thing. I had to retune the LS and HS needles. The engine ran consistently better with the muffler. Also, the needles seem to adjust better.

RE: Help with 31cc Ryobi conversion
 

Yupper...thats what I found also. It is going to be very cold here tomorrow am...going to see how my MB290 Gas/glow engine starts!;) THIS IS Monday the 27th. Darn cold but engine starts very good yet!

RE: Help with 31cc Ryobi conversion
 

Could someone tell me where you can get the ryobi with an EI not the flywheel an magneto. Found some on e-bay but they had the flywheel. I'm am needing the electronic ignition for a good fit in a tight cowl. If somone knew where I could get one I would be thankful

RE: Help with 31cc Ryobi conversion
 

All the engines will have a Flywheel & Mag. This is something you take off and purchase an aftermarket EI unit.
SOmeone could sell you one setup, but you would be better off getting your own engine and buying the parts to complete. Should be able to get it done for 125 or so, with your own engine.

RE: Help with 31cc Ryobi conversion
 

I have now got my grubby little hands on a ryobi. Striped all the weedeater stuff off an made it look alot like a model airplane engine..How can I tell which one I have (28 or 31cc)?..I pulled the flywheel an magneto off an found that it has a real short shaft with a tapper down to the threads. An a really small half moon key(this mean short shaft?). It has a really tinny walbro-324 carb with no choke. I need one with a choke, so what would be a good replacement? I pulled the backplate off an noticed it was very clean on the inside, How ever the conecting rod looks like two chunks of flat steel pressed to one another. Don't look like a real strong setup.Is there a rod replacement that people are using when converting from yard tool to rc?....This engine is perfect with the rear carb an ext.It also looks like one of the Bennett deflector/muffler for a G-38 might work.Will it? Can't wait to get this thing converted an installed on a Great planes RV-4.......One more thing...If you can still see the cross hatchet hone on the cylinder does it need a new ring? Or is it still pretty fresh?

RE: Help with 31cc Ryobi conversion
 

I think all of the new ryobi's are the 31's (the old ones with the more square style covering were hit and miss), somewhere on the case should tell the engine displacement. that is a short shaft engine

look for a 11mm carb, if you can't find one with a choke, make the stock choke plate work or something, nothing wrong with a plate style choke, it's less restrictive than a butterfly choke anyway.

the stock connecting rod is fine up til 8000rpm, so prop it for around 7500rpm on the ground for good measure

take the ring off of the piston and place it in the bore, use a feeler gage and find the ring gap, it's most likely around .01 which is too much for getting decent performance, you can get a frank bowman ring for $14 shipped.

RE: Help with 31cc Ryobi conversion
 

I can't see the size on it anywhere. Heck might not even be a ryobi, but it sure looks like one. The Ring gap is really tight .08. Might get a ring just for good measure

RE: Help with 31cc Ryobi conversion
 

OK my turn HELP!!!!!!!!
I have converted a new Ryobi 31cc from a weed wacker. When I start the engine it will run for about 10 to 15 seconds then die. I noticed that air was getting into the fuel line from the Carb. The only way the engine will start after it dies is to pump the fuel ball pump and it will run for another 15 to 20 seconds. I have tried a different carb, a different rear plate with reed valve and still the same thing. There are two brass lines that come off of the carb. one by the high and low speed adj. and the other is on the other side of tha carb and is bent in a 90 degree angle. which is the feed for the carb? Does anyone know if this is a pressure fuel system where the tank has pressure form the engine? What is the second pipe for if it's not pressure system?

HELP!
Thank You! :eek:

RE: Help with 31cc Ryobi conversion
 

Hello Again!
Forget the HELP I found the problem. When I took the weed wacker apart I didn't look where all the fuel line were hooked up to and as I have been trying to start it, I had the pump bulb between the tank and the carb. It needed to be on the other end of the carb so it sucked the gas into the carb and not pushing it in to the carb. After putting pressure into the carb it would run till the pressure was gone and had no way to suck anymore fuel into the carb threw the pump bulb which acts like a one way valve.
Mike