So I've heard some guys convert weed wacker engines and use them. Can you guys give me any kind of info on this subject?

Have at it! http://www.rcuniverse.com/forum/forumid_92/tt.htm

What kind of airframe do you want to put one on or start with.Say,scale,3D,WWI,WWII,and what WS are you looking to fly.Do you have any airframes right now your thinking about.Just about all of us here have done just about every engine i can think off.I myself do Echos,Stihls,and Husqvarnas.These 3 are some of the lightest and are very good running.Do you have any engines sitting around your thinking about?
1st on left is a stihl 28cc
2nd,middle one is a echo 24cc
3rd is a ryobi 31cci turned cylinder in lathe to round it out to make it look a little nicer.Battery cdi installed.

Hey Buck

I'm getting ready to install my pick up on my Ryobi.
I figure the max. length of the screws will be 1/4 inch.

What did you use? I assume you left the seal in place and drilled the holes.

Did you use screws or bolts?

Thanks for the replies guys. The reason I'm curious about these engines is simply because I'm thinking it would be considerable cheaper to buy a used weed wacker and put the motor in a plane. I'm more into planes like Yaks and edges,but I dont really have anything in mind at the moment. I figured If I could get an engine coverted I'd buy the plane to fit the motor. I'd be looking for something in the 26 - 50cc size. The only plane I might be looking for an engine for is one that I just finished last night,but problem with it is that its a 77" yak with a smaller 1.20 2-stroke engine in that I had sitting on the shelf. And this engine will likely be too underpowered for this plane,so If I can find a good cheap gas engine in it....that would be cool. Another reason I want one of these gas engines is just to play with,so thats another reason the size wont matter. I just have no idea what I'd be getting into,and if it would even really be cheaper in the long run. I've heard rumors that these engine I much heavier then the "made for rc" engines,and for that reason arent practical. I also dont know a thing about what needs to be removed from them,nor what needs to be added to them(carbs,ignitions,exhausts,flywheels,prop hubs,etc). I also have no clue what to look for in a used engine as far as brands,or the simple mechanical setup of them. I've got tons of glow engines,but never got into gas. I just think it would be fun to try this if its going to save alot of money. I've done some searching,but sometimes its good just to have one on one coversations to get the specific answers you need. Thanks again guys!


I just need to start with very basic info I guess.....

I've done a couple, and have come to the conclusion that if you can make your own parts (prop hub, muffler, mounts), you can save money. If you enjoy tinkering with engines, you'll have fun. But if you have to buy the weedwacker and all the parts along with an EI unit, you will spend as much or more money on this than a cheap Chinese rc gas engine.

Good Luck

What cfaw10 says is true to a point.

With the cheap Chinese engine you will always have a poor quality engine.

I like the Echo engines. Great quality, plenty of power and reasonably light.

The older 23.6 engines are real good runners and there are articals here on RCU on how and what to modify.

They are still easy to find in the junk box at most small engine repair shops, usually for free and never more than $20.00.
A lot of the time there is something other than a scored cylinder that put them there.

Bad Carb, leaky gas tank bad ignition ect....

They also run well on Gas-Glow and don't even need an ignition system.
$35.00 will buy you a prop hub and ring set up from Top Cat on E_ay.

So $50.00 will get you going with a good base engine with a new ring ready to run or, $100.00 with an electronic ignition.

This stuff is not rocket science. It's pretty easy for being hard. And it's a LOT of fun.

Starting off with a good engine is important. Other wise you are wasting your money.

It costs just as much to do a 50cc engine as a 20cc engine so don't go small.

Hope this helps......

Yeah,I'd like to get something around a 50cc. What item are common to have 50cc engine in....like chainsaws,or leafblowers,or what? I'll likely get one of these items at auction(lots of them around these parts). Most sell for less then $50. The woman just bought a nice little snow blower for $50 that has a NICE 2-stoke engine in...not sure what size,but I wouldnt mind finding out,lol. Dont think she'd want to hear that though.

I have a couple motors I'm working on, the chain saw motors are good, the Poulan 42CC is good and the Homelite 45 is a good one also. What he says about the Echo is true. First one you take apart you will see there first rate little motors. Look in the RCU motors for sale, sometime there are some there at a good price.

I used bolts,machine screws.I think 6x32 or 8x24 sounds a little big,I used whatever size screw fit through the stock slots on the rcexcl ign.I then tapped the case.Be careful of the front bearing.I ended up using the longer stemmed pickup and had to remove the bearing i think.Just check the front bearing placement before you start drilling.If ya drill into the metal lip of the seal it wont matter.!/4 inch is fine,1/8th for sensor,and 1/8th for case.

Chainsaw are the highest performance engines.

Echo makes a 50cc Chainsaw. I purchased one on E_ay cut it down and never finished it.

It looks real light and I know it's powerful.

BME engines are all Echo based.

If ya want an Echo 50cc and want it a rail mount like the BME 44 was Look for a CS-510-or520.If ya can find or want a new short block look for this number[SB1055.]

I seen today that lowes has cheap "Bolen" 31cc weed wackers for about $75. I know these are probably cheaper engines,but would one of these work? The also have troy-built ones the same size for just alittle more. I'm thinking an engine this size might work for my yak. I flew it for the first time today with its GMS 1.20 and it is indeed quite underpowered.

So what would you guys think of an engine this size for this plane? Or would smaller 31cc cheap engine just weigh too much and be nothing but junk? I think a 50cc might be too big for this plane I need a motor for though.

Thanks again....all this info is helping.

the bolens and troy built are the same engine, more commonly known as the Ryobi 31cc (oddly enough not really used on ryobi weedie's anymore)

well, I just ran my MacCulloch 32cc that's running on gas/glow today, got an RPM of 7500 with mild porting and a worn ring on an APC 18 8 prop, according to thrust calc it said about 17.5lb thrust, I didn't get a weight on the engine in this configuration though, I don't have a ryobi on the bench or I'd offer to give you a weight, people seem to be getting about 7300rpm on 18 8 props on the ryobi's too I think, someone else will chime in I'm sure

Dont do that.Go to Wmart and buy the poulan chainsaw,42cc.There only $99 or $109,somthing like that.They are quite powerful and would fly that yak at least decent or better in my opinion.This was one of brillellis first motors.I had one also.I converted it and sold it to a guy in Texas.The 42 would be easier than the 46.The 46 needs an aluminum adaptor mounted to the intake on carb since it had a rubber boot.I think CHIGNS sells a complete conversion kit.If not talk to Ralph at rcigns.

the 42 would require less plane modification also, the Ryobi is an ok engine, but is super long because it is a rear induction piece

Hey,I like that walmart 42 idea. I was going to go there today to look,but didnt. Can you guys ellaborate alittle more on what I'd have to do to it to make it r/c ready? And Buck...what is "CHIGNS"? I did a brief search and didnt find anything(yes,I'm ignorant on this subject,lol). A nice conv. kit would be nice. And for the price of the engine,I could afford to spend a few extra dollars. If it sound do-able,I might just have to go to walmart this weekend!u


You guys are gonna make me into a "gasser" junkie yet. My glow engines are already getting jealous! And I really do appreciate your help and patience with me as I am VERY dumb when it comes to this gas stuff. I've only ever seen one gas engine at our small flying club,and couldnt tell you anything about it except that its a 50cc on an 80some inch yak.

CH Ignitions I think they go as CHIGN too, that should help

once you get to the right point, the engine pretty much falls out of the saw (assuming it's like the 46 I have on the bench), you'll have what looks like a really big glow engine with some pretty big cooling fins compared to what we're used to. the 42cc engine has the magneto mounted to the saw case so it doesn't have the bosses on the head like many engines or a bunch of aluminum stuff to cut off.

there is also the option of going with the gas/glow mixture which makes for a lighter and simpler setup, use the stock carb and stuff, convert the gas tank to be able to run gas (new stopper, clunk line and fuel line) and get a glow plug adapter and a 4 stroke glow plug. make a mixture of one part 10% nitro 10% oil glow fuel (usually labeled for use in large super tiger engines, Omega has it as SuperT or something) and 3 parts premium gas, that gives you the right oil ratio and enough nitro to keep the plug lit.

Here is there website:
www.ch-ignitions.com
Heres Ralphs:
www.rcignitions.com
Do a search for poulan,or poulan 42,or poulan 46 on the bottom right corner of the first landing page here for conversions.Search this forum only.Should be lots of pics.Just look at the pic and make yours look like it.Any other questions just ask here,we will all help in one way or another.And nobodys dumb here,just either been misinformed or not informed enough.You could also buy a used conversion motor pretty cheap,not be the right size.But you could look at it and then youd know how to do your next one.Besides that,youd have to buy another plane.

Here's a picture of my 42cc Poulan on gas/glow setup along with my homemade starter. Check out this thread for more info on it.
[link]http://Success! Poulan 42cc on gas/glow[/link].

Plastic Master-Is that a homemade starter??? Interesting and neat idea if it works. Thats what i love about this forum-Ingenious ideas from some clever people. Does it work? probably don't need it with EI Ignition.

Frenchie79, indeed it does work. It's a homemade starter that I made from the recoil of a weedeater. It works very well. Read the thread that I linked to for a full description of it. I don't have this plane and engine anymore because I crashed it a few weeks ago and totally destroyed the plane and engine. I was running the engine on gas/glow and used my homemade starter to start it for the first flight of the day. After that, I could usually flip start it with my hand (wearing a leather glove of course).

I just checked walmart and they have that 42cc poulan,but its $148.00.

Welp....my buddy gave me a U.S. engines 41cc gas motor to put on it and use. I ripped the old ladys' snow blower apart to find out what motor was in that and its a tecumseh 3HP 98cc engine...so thats no good. The 41 my buddy gave me seems pretty heavy,but I think it will work good. It has the flywheel/magneto setup on it. Man,it just looks like a BEAST compared my 1.20 glow I had in it,lol. I still plan on getting my own motor to covert yet though.


...on a side not,I thought that 3HP rating on that 98cc tecumseh was really low for that sized motor [sm=71_71.gif]

Well these high gas prices have hit walmart then also.They werent that high here a while back.Maybe its just here in AZ there not as much.Ive never used one on a cactus.Anyway,a us 41 is a good engine,i had one on an extra once.