SPADMONIAN

Help! I have converted a couple of the 31cc Ryobis, but am stuck at about 6800 rpm. I have gone to smaller props and larger carbs, but still no gains. How do I identify the rpm limiting coils? What is a good coil and how do I identify it?
There are two sets of numbers on my coils. For example, there is the number RE 31837 in raised letters on the flywheel side of the coil, and 0 095 stamped into the front. Another example is 4036201 in raised numbers on the flywheel side and 3 038 in white letters this time on the front of the coil. The latter coil has a small square added to the top at the shorting lug. (I am using these as an example and have not run these tow to test them yet) The Phelon web site was useless. Someone out there has got to know how to identify the many different coils.
Thanks!!!!

w8ye

My Feedback: (16)

I right off don't know the answer to your question but I do have a couple of Ryobi's. They don't seem to be RPM limited by the coil. However on do know that these kinds of coild do exist.

I take it that you have tried some smaller props and never got past 6800?

In a way there is nothing wrong with 6800 RPM. The engine is actually somewhat of a torque type motor and you want to prop them to where they turn no more than 7500 rpm static anyway.

Try an 18-8 on the engine and see what it turns? Put a bigger carb on it to see if you can get it up to 6800. A new coil will set you back $40. You need to find a used one or live with what you have.

There could be a problem with 6800 rpm static. When you get up in the air and dive is the engine going to make all kinds of cutting out noises etc? You know engines unload a little up in the air anyway.

Good luck

Jim

SPADMONIAN

Thanks for the advice. As I wrote in the question, I have gone to a much smaller prop and to a much larger carb. It is funny what you write about torque. This thing spins a 20x10 with no problem, but limits the rpm even further. I would not fly it, but it was fun to experiment. (I will use a 16X8 for my first plane) I messed with fuel mix and mufflers too. WARNING!! Running the engine without a muffler for even a few seconds will cause a huge day long headache! LOL
If anyone has more info, please help!
Thanks

w8ye

My Feedback: (16)

My Ryobi's are stock and I use a 16-10 mas prop. Seems to work OK. By stock, I mean no porting, stock muffler, and orginal muffler but they have 1/2" outlets. I also Statically balanced the flywheel. It doesn't seem to vibrate any more than any other weed whacker. I also have McCollochs and Homelites. Most Ryobi flywheels are off-balance to counteract (or to help counterbance) vibration in the weed whacker. I changed them before I read about the counterbalance action. When I read about this, I had noticed the situation but was bull headed or something. Anyway, they run fine vibration wise. The engines have Carr Precision conversion pieces on them.

To put a Zenoah 23 carb on them and a more open exhaust, you can run a 18-8 on them.

There was some talk sometime back about these coils on rconline.com/rco. You would have to do a search on Ryobi's and go back a year maybe to find it. I'm trying to think who had the scoop. Wheather it was rcignition or the the guy from rcfaq? Might have been someone else? It may be on rcfaq. Find it with Google.

good luck,

Jim

SPADMONIAN

Thanks for the info. In my last reply, I used the word funny. I should have written that what you said about torque was right on the mark. I am glad you took it the right way. I too remember something that I read and probably did see it on RCO. It must have been in the last year. That is when I found RCO.
I too have stock mufflers. I take the time to "Cook" out the old gunk that sometimes clogs them up. I have an "Evra" with a straight pipe that is just a Ryobi with mounting lugs. I have not run it yet. I ran it's pipe on my Ryobi. Once again, day long headache from the unbelievable noise. Thanks again for the advice and info an what works for you. It helps!
SPADMONIAN

w8ye

My Feedback: (16)

Actually one of my Ryobi's is not exactly a Ryobi. Well, yes & no. It is a 1985 Lawn Boy. But it's a Ryobi if you ever saw one. I put all Ryobi conversion parts on it and they fit perfectly. I used it as a weed whacker for years. There are others that we may refer to as Ryobi's. They are like IBEC, Ryan, & Lawn Boy. Some Sears weed whackers are Ryobi's. Also there are other brands of weed Whackers that actually have a Ryobi engine in them.

By Ryobi, I'm refering to the 31cc version. There are also other sizes. Most are made completly different from the 31cc. The 31 seems to be the most popular version.

There are some things about the 31 that are rather crude in a way. Like for instance, the stamped steel connecting rod, The external balancing flywheel, and the long narrow design. Also the Ryobi 31 is one of the few engines with reed valve induction. In spite of its crudeness, it makes a pretty good model airplane engine.

Jim

SPADMONIAN

The engines I use are also the 31cc version. I have an "IDC" and a "Ryan" too. Have you seen the "Evra"? It is just a factory converted Ryobi 31cc with mounting lugs built into the crankcase. It is too bad that they are not still making the case. It would be well worth the cost of tooling up to sell to the folks who like the engine. It was distributed by Hobby Lobby. I found one at a swap meet with the original box and all of the paperwork. It has a notched pulley on the front to rope start it. I have seen them sell for over $100 on the net. It was sold as the " Evra 190".
I still wish someone out there knew how to read the numbers on the coils and tell them apart. I will try the coil off of the Ryan next to see if there is a difference.
Thanks again for your info.