Hey, i just got a yardmachines 2800M weed wacker with a 31cc engine. ive got pretty much everything ready to go except the mounts and hub and was wondering what brand of engine is used in the yardmachines weed wackers? the shop that i got it from thought it was a ryobi (the carb is attached to the backplate) but they werent 100% sure if that was correct or not. does anyone know what engine this is? another thing, i was hand flipping this engine and couldnt turn it fast enogh to get a spark. when i turned it with a drill, it had very good spark. because i dont have an electric starter, i was wondering what i could do as far as mods so i can hand start this engine. (i dont want to use EI b/c my budget is pretty tight right now)
any input would be greatly appreciated.
thanks

Andrew,
It is most likely a 31cc Ryobi. They come in a short and long shaft versions. You need to know this to order a hub. Most of the newer ones have the flywheel housing cast into the crankcase. You have to cut it away with a hacksaw etc. If you retain the mag ignition, you will have to live with the more difficult starting. Its not so bad.

Dave

thanx for the input, ive got all the trimming and whatnot finished (actually didnt take that long) and am ready for the parts to come.
a guy at the club told me i had to modify the reed valve inside the backplate in order for it to run. can somebody help clarify what i have to do (if anything) to the reed valve?

Put an ignition on it and fly it. After you get all the bugs worked out, then you can add some bugs of your chioice.
If it runs with the stock reed valve in the weedwacker, why wouldn't it run the sam in a airplane??

Try the Gas/glow mix with a adapter that just screws in spark-plug hole. Capt,n

andrew
most guys open up the reed valve limiter so a 1\8 inch allen will fit between the limiter and the valve for a little more intake flow its not that critical of a modification . read the back articles in this forum there is a lot of info on what to do for the ryobi ,its usually pretty good stock depending on wich one you get.

It runs fine when it's turning a piece of nylon string. Why wouldn't it run fine when it's turning a piece of lumber?
Leave the reed valve and reed stop alone untill you get it running and ready to bolt up to a firewall. Just leave the engine stock and convert it. When you start screwing with things that you've never dealt with before--thats when you get into trouble. I'm sure your a competent engine builder and tuner--but jst do it stock right now. Get it converted and get it running. You can pick these engines up cheap and modify one later on. For now--just enjoy the fact that it will turn a nice prop for 45 minutes on 12oz of fuel.

There are a few things you need to know before you order parts:
Long shaft sticks out the front of the engine about 5"
Short shaft only sticks out about an inch
Long shaft has 2 different keys to hold the magneto in place. Thin key is only about 1/16" thick. Thick key is about 1/8". Identify before you order the hub.
Some engines have the key cast into the magneto. There is no steel key to place on the crank shaft. It's cast into the magneto and slips right on and holds the magneto in place.

Do a dearch for duration in this forum when you decide that your hooked on Ryobi conversions. You can port these engines out and add bigger carbs. You can turn the cylinder down to increase the compression. Leave the first engine stock and enjoy it. Then go buy another one and port the hell out of it. You won't screw it up if you spend some time doing searches in this forum and read everything you can about the Ryobi engine. Guys like Dave Wallace and FlipFlop have posted duration numbers in this forum. You should not exceed those numbers unless you know where to find a tuned pipe for a Ryobi. Too much porting and they don't run worth a darn unless you slap a pipe on them. I can tell you from personal experience that 8700--8800RPM on a Ryobi won't last longer than about 2hrs run time--maybe less. If you port it and add a bigger carb--keep sticking bigger props on it. You don't want more than about 7300--7600RPM on the bench. Thats MAX. Have you seen the rod? Thats what lets go, and it's not pretty.

Have a blast. Welcome to your newest addiction.

thanx for the input guys, i will leave the reed valve alone. as far as what i need for parts, ive already contacted wackerengines and he has what i need. now if only payday was today......
another thing, i was looking at the CH ignition web page, and they have a "jumpstart" system available that uses 4 aa batteries that is designed to help ease starting on an engine with mag ignition. is there any way i can make my own?

Andrew,
Before you spend money on a bandaid, like jumpstart why not get the complete CH electronic ignition with hub, ready to bolt on from JAG engines. Heres the link.

http://www.jagengines.com/pricelist.htm

http://www.jagengines.com/images/C_H700.jpg

Dave

i could do that, but im on a fairly tight budget right now.