cfaw10

Hi, I'm getting into gas this spring, and looking for info/advice on a cheap conversion for a four star 120. Would the homelite 33cc conversion be a good match? Or would I be better off sacrificing some power for the lighter homelite 25 or the ryobi 31? Any engine would have the stock ingition and carb. Would like it to have decent vertical, but doesn't have to be unlimited. Tried to weigh all the numbers and specs on different threads. Got a massive headache. Just looking for opinions of people with these engines in this plane.

----Thanks----

Rcpilot

My Feedback: (78)

I did a build thread in the Kit Forum.

Go to the kit forum and do a search for 4*120 Build Thread.

I used a Ryobi 31cc engine on C&H. Pretty nice flying plane.

av8tor1977

My Feedback: (6)

I would go with the Homelite 33cc.

AV8TOR

davewallace

My Feedback: (29)

cfaw10,
The typical Ryobi weighs 64oz. while the 33 Homey is 65oz. My 25 weighs 57oz. while a typical 25 weighs 60oz. I trimmee away as much as I could to save 3oz. All of these weights are with mag igniton. The Ryobi is the cheapest and the 33cc is the most powerful and easiest, if you get a newer engine. The 25 and newer 31 require triming the flywheel shroud.

Dave

cfaw10

Thanks for all the info. I like the looks of rcpilet's plane with the cheeks left on, but the one I'm getting has already been built. I think it will be easier to trim the cheeks than to move the firewall for a ryobi. I can always add a cowl later. Plus, I just talked to a small engine guy and he offered to give me 2 homelite weedeaters. Not sure of the displacement. As I said earlier, I'm new to gas as well as large planes (been flying .40 size glows). Any and all advice is welcome.

--------thanks----------

andrew66

if you have the 33, use it. i would scrap the mag and go with either electronic ignition or run it on a gas glow mix to keep the weight down.
the homelite 25 would work too.
i would only use the ryobi in a scale plane that you dont want a carb sticking out of.

davewallace

My Feedback: (29)

Hi,
If you don't move the fire wall back a inch or two, you will need to put the servos in the tail to offset the 4lbs motor. Since it is already built, you can do a mockup, moving parts around to acheive balance. Beefup the airframe at wing center joint, tail feathers, landing gear and firewall. Use two servos for ailerons and elevators. Carbon fiber strips can be applied to a completed airframe. Don't forget to keep all radio equipment and wiring 8 to 12 inches away from the engine. Use a plastic throttle pushrod and no metal to metal contacts that can rattle and cause RFI. Good luck.

Dave

cfaw10

Thanks for all the info. I haven't had a chance to pick the plane up yet. Working 7 days a week. Hopefully will have it and the engine by next weekend. What are the specs on your 33? Carb size, prop size, type of muffler? What kind of rpms and actual thrust do you get?

ALW Phantom

My Feedback: (2)

Has anyone run a Homelite 33 on Gas/Glow? If so is it the same as the 25/30 Gas/Glow thread or does the large displacement hurt the gas/Glow idea? Could you go up to a 45 Homelite as well?

xrae

The carb on mine is a HDB 10-1 and has 13.49mm venturi. I bought the carb and muffler from wackerengines. As far as prop size and rpms. I've been bench running mine with a 20 6-10 zinger prop. I thought that might have been to large but according to my tach it's turning it at 8500-8600 rpm. I'm not sure if I can trust my tach. So the rpm readings aren't written in stone yet. Maybe someone that has more exp with the 33cc will post what they have been getting and with what size prop.

Rick

P.S. Anyone ever looking to swap stuff with others in the engine conversion forum?

cfaw10

Thanks, Rick
Engine should be here tomorrow. New homelite 33 already converted---sounded like a good deal at $100. I'll post results when I get on the bench and running. Guess I'll break it in with a 18x6. Any other suggestions???

av8tor1977

My Feedback: (6)

I haven't personally done a Homelite 33cc, but some here in the forum have. Nice engine. The Homelite 25/30cc spoken of in the "Gas/Glow" thread are different models, but the 33cc should do fine with it. I'm running a Poulan 42cc on Gas/Glow with no problems. Since you are rather new to this, I would recommend getting it running and broken in on gasoline in order to get used to it before switching to Gas/Glow. Gas/Glow is not difficult, but it is a little different. There are subtle differences like the fact that with Gas/Glow operation, the engine likes the idle a little richer than normal, etc....

An 18 x 8 prop would probably be about right for the 33cc, and I recommend APC props personally.

AV8TOR

flygilmore

I just finished a Homelite 33cc. It was a great success-first conversion that I have done. I couldn't ask for a better running engine and it has PLENTY of power. I am using a Xoar 18x6 to power a Jerry's Big Boy arf. This motor will hover the Big Boy at less than half throttle and has unlimited verticle. I am using the motor with stock ignition and a Wacker Engines prop hub/muffler.

cfaw10

I've heard different ratios on the oil. What's the best brand and mix, and do I need to change the ratio after so much break in time?

av8tor1977

My Feedback: (6)

I use 40 to 1 mix when I'm not running Gas/Glow, and I use Pennzoil for Air Cooled Motors. (Careful; there's several types of Pennzoil and you want the "for Air Cooled". After a couple of gallons, you can switch to a synthetic if you like. (Amsoil?)

AV8TOR

cfaw10

OK. Here's some pics of the engine. Walbro carb with 28 stamped on the inside of the barrel. 2 brass lines on the back (large and small), and 2 plastic fittings on the front of the carb (white and black). How do I hook these up?

cfaw10

After looking at it again I realized the plastic "fittings" were the needles. Which is high speed and which is low?

jrjr2u

take a clean piece of fuel line, put it on one nipple and blow. If you can blow through it, plug that one and hook the other one to the clunk line in your tank.
As far as high and low goes, isn't there a H and a L stamped in the carb body by each needle?

flygilmore

The small brass line needs to be crimped and soldered-it is for the primer bulb. The low speed needle is closest to the block and as mentioned, there should be at least an H below the outer one. I ran a 40:1 for the first couple of tanks and am switching to Pennzoil air cooled at 50:1- after taking the motor out of the saw, I had to richen both needles since the airfilter etc. is so restrictive. I also had to trim down the casing around the needles so that I could grind in adjustment slots as the stock ones had no way to adjust them. This engine has run 100% perfectly and I couldn't ask for better!

what muffler are you going to use? The stock one weighs over 9oz and the Wacker Engines weighs 4.5oz

captinjohn

flygilmore: I know the crimping and solder will work...but it is more easy to use a short piece of fuel line and a rivet to plug brass tube. Who knows, you may want to use that line again on another set-up. Capt,n P.S. Great combo you got.....where is best price on a Bigboy!!!

xrae

Just put up my 33cc for the night. I borrowed a friend’s tach which happens to be a tower hobbies tach like mine lol. I'm getting 8500-8600 rpm consistently with a 20" 6-10 zinger prop. I even pulled it outside to make sure my lights weren't messing with the tachs. That big bore carb is really doing the trick for this motor. I can’t wait to get a few gallons of gas through her. I still need to research what the idle rpm should be but hopefully that won't be hard to set. Other than the carb being very sensitive to throttle response I'm extremely please for my first conversion. Now I just need to finish my super decathlon and get a new motor for my ace 4-120. Anyone wanna trade a gas motor for a st2500.


P.S. This really is the conversion forums. You guys converted me not just to gas engines but you converted me to making my own gas engines. My wallet and my wife thank you.

av8tor1977

My Feedback: (6)

What kind of an engine would you like in trade for that Super Tiger?

AV8TOR

xrae

I don't know really. I need something that runs and can fly my 4-120. The 33cc is just too much engine for it. Feel free to PM me if you like Av8tor. The st2500 does run i'm just horrible with big glow engines. I've never been able to set the needles right in any I've ever owned.


Rick

flygilmore

I got one of the last remaining Big Boy ARF's that Morris Hobbies had (on ebay). Robert said that it would be several years before they carried the arf again. They will, however, keep the kit version in stock. As it was, the arfs were going cheaper than the kit for a couple of weeks at the end.

av8tor1977

My Feedback: (6)

I'll look through my engines tomorrow and see what I might have. I sold a couple of Homelite 25cc engines I had to a friend. I have some Echo 23.6cc and Homelite 30cc engines I don't want to part with, and I have a number of larger engines... I'll check and get back with you.

Does it have to have magneto ignition? Most 120 size planes do better without the weight of the mag; run on either battery/cd ignition or Gas/Glow. I never run magneto ignition, and a lot of the engines I have I've already stripped off the mag parts and thrown them away....

The only thing I'm running a magneto on is my gas powered Margarita Maker.

Have fun, and congrats on your success,
AV8TOR