Help with 31cc Ryobi conversion
 

As stated in a previous post. I have a Ryobi 31cc converted to EI with a CH ignitions prop adapter and their magnetic sensor. I'm using an S/S ignition system which is almost new. I have a Walbro WT-324 carb. on it. I'm running a Zinger Pro 16x8 prop but no muffler on the engine yet. I have the timing around 30 deg. BTDC. I replaced the throttle shaft so I could add a throttle arm on it. BTW, Ralph Cunningham sent me the replacement throttle. Great guy!! Anyway, the engine starts great. Choke it till it fires, choke off, one or two flips and it's running. Now here is the problem(s). The engine will idle but I have the idle stop screw all the way out and it still idles at about 2300 RPM. I can add throttle quickly and it will take throttle great. I have the top end adjusted pretty close and the bottom end pretty good I think. When you let it come to idle quickly, it will quit. One or two flips and it's running again and idling as before. I have the LS needle out about 2 1/4 turns. Any leaner and it won't transition quickly to full throttle. I have the spark plug gap at .020" which is brand new.
I did have the butterfly out when I changed the throttle shaft out but I think it is the right way. I have compared it to other carbs and it moves the right direction and is in with correct side out. I do have a little light showing around the sides of the butterfly but I have tried to adjust it but can't seem to get it touch all the way around. The butterfly does touch at the top and bottom. I have looked at the carb end where the butterfly is and there is one tiny hole exposed like the other carbs I looked at. As you open the butterfly, the is another tiny hole that then becomes exposed. I believe these are for the low speed circuit because carb cleaner came out of these holes when I sprayed carb cleaner in the hole where the LS needle is.
Any Ryobi guru's have any ideas?
Thanks

RE: Help with 31cc Ryobi conversion
 

too much air getting past the throttle butterfly, are there any holes in the plate? if so, solder them shut one at a time until you get the idle you want, and if there's a little hump of material removed down by those holes in the carb bore, try soldering some of that down as a last resort.

is this carb the stock or larger than stock?

RE: Help with 31cc Ryobi conversion
 

The carb plate doesn't have any holes in it so there is nothing to solder shut. This is a bigger carb than the original. It seems that the WT-324 is the carb recommended for this conversion. The original carb is 7.54 mm and the WT-324 is 11.1 mm.

RE: Help with 31cc Ryobi conversion
 

Take some wd40 and spray around the bottom of carb and around the black plastic base that bolts up to the crankcase and check for leaks.If theres one the engine will change rpm.Do this at idle.

RE: Help with 31cc Ryobi conversion
 

yep, that would explain why the needle is needing to be out that far

RE: Help with 31cc Ryobi conversion
 

I haven't had a chance to try the WD40. I have looked over the plastic back plate where the carb mounts and the reed valve area and didn't see anything where air could leak. I used red RTV to seal the gasket to the crankcase and the back plate. One thing I noticed is that the reed valve isn't sealing when it is just sitting in place. The engine starts and runs good so I can't see how the reed valve not seating fully is the trouble. Is the reed supposed to seat when the engine isn't running? Will the reed seat when the engine is running?
Thanks

RE: Help with 31cc Ryobi conversion
 

A few months back some buddies at the field were having idle problems with a G-62. The end result turned out to be a crack in the plastic carb spacer. They replaced the carb and plastic spacer from another G-62 and fixed it. You couldnt see the crack until you had the spacer off the engine.
Edwin

RE: Help with 31cc Ryobi conversion
 

The last time I had this happen, it was the carb butterfly being worn and allowing too much air to pass when closed. Hold the carb up to a light, and when the butterfly is closed, you should not see any light showing through the carb. This can also happen if the butterfly isn't aligned perfectly when installed.

Good luck,
AV8TOR

RE: Help with 31cc Ryobi conversion
 

The carb is new and has never been mounted until I installed it. I did remove the the butterfly to install a different throttle shaft. I do see some light but it shows around where the shaft is. I think I have it aligned properly. I have tried numerous times to get it to touch all the way around but can't seem to. I looked at other carbs that are new in a box and they have some light showing in the same general areas. I'll try to run it this week some more and try the WD40 trick to see if anything shows up. Is there a way to align the butterfly properly? Mine is touching about 95% of the opening but like I said, I have other carbs that are showing about the same amount of light.
Thanks

RE: Help with 31cc Ryobi conversion
 

I tried the WT-324 on my Homelite 25cc and never had any luck with it. I bought the carb for a G26 at my LHS (WT-644?) and haven't had a problem since. Just want to point out it may be the carb.

RE: Help with 31cc Ryobi conversion
 

Did you mean to say no muffler at all[X(] or just not a modified muffler yet? The right back pressure (at the right time) is a big part 2 stroke tuning. With no back pressure the intake charge can blow right out the exhaust port at certain RPM. Trouble is with bigger carb the stock muffler can have too much back pressure esp. at higher revs. A good set up witih 11mm carb is replace the 1/3"ID exhaust outlet pipe with 7/16"ID. Bigger than that is not necessarily better. Means a little cutting and brazing but at any rate I wouldn't try to tune the intake without the muff you intend to run.

RE: Help with 31cc Ryobi conversion
 

I don't have a muffler at all on it. I want to make sure it runs fine before I spend money on a muffler from wackerengines.com. I need it to idle reliably and at a lower idle. The darn thing starts great and runs WOT great. The HS needle adjusted fine. It's the darn idle that baffles me. I haven't had a chance to run it any more. I took the carb off and checked the butterfly again. I tried once again to adjust the butterfly to get more of a seal. I hope to run it more in the next few days.
Thanks

RE: Help with 31cc Ryobi conversion
 

Madman,
You won't get it right without a muffler... i'm afraid you need to invest in one to find out how it runs an then determine what it will take to make it purr.
Cheers,

RE: Help with 31cc Ryobi conversion
 

Not having a muffler shouldn't cause it to idle too fast. If I understand the problem, he can't get the engine to idle slower even with the carb butterly all the way shut. Sounds like it is getting air from somewhere. Pull it all back apart and go over it with a "fine tooth comb". Somewhere air is getting in, and supporting the fast idle even with the carb butterfly shut. Cylinder base gasket, carb adapter/reed block, spark plug not seating/sealing; somewhere air is getting in that shouldn't.

AV8TOR

RE: Help with 31cc Ryobi conversion
 

What's really confusing is how he handles all the noise[:-].

RE: Help with 31cc Ryobi conversion
 

In order to get the engine to run properly, there needs to be backpressure. Having no muffler likely won't cause his problems but the engine will never tune properly so why avoid the inevitable... put a freaking muffler on it and eliminate that issue is all I'm saying.
Cheers,

RE: Help with 31cc Ryobi conversion
 

EAR PLUGS!!!!!!!!!!!!!!

RE: Help with 31cc Ryobi conversion
 

Actually most engine builders test their engines for Max. rpm with no muffler.

Ralph at rcignitions.com is one of those engine builders.

RE: Help with 31cc Ryobi conversion
 

That would be prudent...

Cheers,

RE: Help with 31cc Ryobi conversion
 

And if one happens to want to use a tuned pipe, the first step in the process is to check WOT rpm, WITHOUT A MUFFLER.

AV8TOR

RE: Help with 31cc Ryobi conversion
 

So when you tune the pipe, do you tune it for WOT and you're done?
Cheers,

RE: Help with 31cc Ryobi conversion
 

No, your wide open throttle rpms with no muffler gives you a baseline. Then you install the tuned pipe long, and start shortening it a little (about a quarter inch) at a time. When the rpms stop increasing, make the setup about 1/4" longer and fly it. The rpms you end up with over and above what it did without a muffler is an indication of the increased power the pipe is providing. (and lets you know it's working!)

AV8TOR

RE: Help with 31cc Ryobi conversion
 

AV8TOR, I did have a conversion to gas/glow running super...for a short time...read about it in another posting. Capt,n P.S. How is that Echo doing I sold you?

RE: Help with 31cc Ryobi conversion
 

Yeah, I answered that in the other thread Captain. But I just had another thought....

If that engine was new or rebuilt, it might have "eaten" the glow plug. I have found that when running a new or rebuilt engine on Gas/Glow, that it will usually ruin a glow plug while the engine starts breaking in during the first few tanks of fuel. The tiny metallic particles shed during the initial break in contaminate the plug. I usually use an old, crappy glow plug for break in for that reason. After a few tanks of fuel, you can put a good glow plug in, and then they last a really long time.

AV8TOR

RE: Help with 31cc Ryobi conversion
 

Made some headway on this conversion. I took the carb off and took it partially apart to clean it up. Readjusted the throttle plate. I only see light where the shaft goes thru the body. I also put gasket sealer on the carb base gasket. I seems to run better now and idle a little lower. I think the higher idle is carb related. I sprayed WD40 around the base of the carb and back plate gasket. I'm not sure what was supposed to happen but nothing changed at idle. I'm able to lean the LS needle more now. I even had to richen the HS needle some. The high speed is a little rich. Transition to WOT is pretty smooth. If I let it idle for abut 3 minutes and then open the throttle quickly, it spits a little gas from the carb and stumbles ever so slightly thens clears up. Once it's cleared out, it throttles up quickly nice. The LS might be a little rich yet. I want to get a muffler and 18X6 prop on it before I fine tune it.
I did notice that when I sprayed WD40 around the carb, the WD40 would run down to the open exhaust which would atomize it. It would then get sucked into the carb and the idle would increase.

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.