Mike2002

I just stumbled over a Homelite weedeater gas engine and I am guessing that it is 25cc. I would really like to know what I need to do to get it suitable to be an engine for an r/c airplane. It seems like the engine has a plastic backplate on it and some of the gaskets may be a little worn out. The reason that I want to use this engine is because I don't want to spend hundreds of dollars on a gasoline engine when I have this engine that might work in an airplane.

Tmoth4

My Feedback: (1)

It could be a 25cc or a 30cc. I have converted a few of these, and they run great. They are a little on the heavy side and are not super powerful, but will fly 12-14 lb. planes. You'll have to remove most of the aluminum flange that's around the front of the crank case, but leave enough to hold the coil in place. I did this with a hack saw and files. You'll also want to remove the fins from the front of the flywheel, and the steel pins and tabs and springs that are on the front of the flywheel for the recoil starter. Most people have the front of the flywheel machined flat, but I cleaned it up with files too. It has to be as flat as possible. There might also be a little hole in the cylinder above the exhaust opening which should be plugged to increase compression. I don't remember the backplate being plastic, but metal.

I got my conversion kits from carrprecision.com. It consists of a turned prop hub, which slides over the crankshaft, and a mounting plate which attaches to the back of the engine, on top of the back plate. Check out Carr's website for more info. and look at their model gallery, too.

kevin mcgrath

My Feedback: (1)

The reason you arent getting much of a reaction is that this subject has been done to death.....do a search under Ryobi or Weeder conversions and you will find more information than you will need....

w8ye

My Feedback: (16)

Go with what TMOTH4 says, You can saw and file on the plastic back plate till you get it like you want it. Get a resistor plug for it. If your carb doesn't have both a high and a low speed needle valve, then you will need a new carb. They all cost the same so get the bigger hop up carb from Carr when you order your other parts. get the carb inlet velocity stack from Carr or you will have a stream of gasolene down the sside of your plane.

25 Engine with 16-10 completly stock does 7000 w/16-10. It will turn a 18-8 with the bigger carb.

There is most often a 25 or a 30 cast in small numbers on the cyclinder body. 30's are rare in weed whackers.

Don't forget to balance your flywheel after you get done breaking the fins off with the pliers?

Good luck,

Jim

Tmoth4

My Feedback: (1)

w8ye,
Sounds like you know your Homelites.
A friend got a recent model 25cc that has no low speed needle. He coudn't get his to idle down. He found a small hole drilled in the throttle butterfly and he plugged it. Now it runs fine. Maybe it's not necessary to replace the carb, unless you want one with a bigger throat for more performance.
Waddya think?

I have 2 newer 25cc Homelites that I was planning on using in another twin airplane and they don't have low speed needles. I don't want to buy 2 new carbs if I don't have to.

P.S.
Were you at the Shelby airfair last summer? I flew the Tigermoth and the Cessna Bamboo Bomber twin there. Both are powered by Homelites.

Jim

w8ye

My Feedback: (16)

Well, naturally, I was there. I saw your planes. I remember well the Bobcat. I live on the other side of town. I was a spectator. I've been there every year since about 1989 or 90. Its the only one I go to. But I have never worked for Dick Shephard there. I've known him since back in the 60's when I would be flying control line out there and he would be flying R/C over on the sod runway.

I have a Homelite 30 that I bought as a new John Deere short block. It has all Carr parts on it. I have an identical 25 that was a weed whacker that I bought on sale at Quality Farm And Country. I have both because the electronic module on my 30 was defective and would cut out above 6000. I couldn't find another Walbro (For Sure) module at any of the chain saw dealers. So I stole one from my 25 weed whacker. I had to take it all apart to get the coil. So I just made an airplane engine out of it. I got a replacement Walbro coil from Daniels.

I did them in 1999. They are unmodified except for the carb. The carbs cost $40 They are 7/16" but they sure wake up the motor. I also have two McCullough 32's. They have 1/2" carbs on them that I got from Mark Daniel at Daniel's Hobbies in Berlin Heights. He gave me a good deal on them. He got them from Warehouse Hobbies.

I have another Homelite 30 that turns 1,000 rpm more than the others. There's not too much left of the original Homelite. It's called a Wolfe Predator. It has a 27/64 carb on it and CH synchro-spark ignition.

The McCullough's don't seem to have any more power than a Homelite 30. I also have a Ryobi that is bone stock. One of my McCullough's was hopped up a little by The guy on here from River ton Wyoming. It runs about 300 rpm better than the unmodified one.

If you get the carb insulator from an electric start Homelite, It mounts the carb at a different angle and the throttle arm is a straight pull back to the servo.

The Walbro mags are a lot hotter than the Phelons. The Zama carbs run about the same as the Walbro's.

There was another guy in Mansfield that had three 25's. He had the 7/16's carbs on two of them. He passed away last year this time with a sudden heart attack. He had one on a Venture 60 with the nose cut back. A picture of it is on the Venture web site. He had another on some kind off "Stick" airplane about the size of a Joss stick but that wasn't what it was. The third one was on a Dynaflite FlyBaby.

If I see your T-50 this year, I will look you up and we'll talk?

Enjoy,

Jim

Tmoth4

My Feedback: (1)

Jim,
The Tigermoth has a 30cc Homelite in it, cuz that's what the weedwhacker box said. It didn't have much power until I plugged the hole above the exhaust port. It flies the plane OK, but I would like to get a little more power out of it so I can do better aerobatics and swing an 18" prop. I think I'll get the bigger carb from Carr like you suggested. I don't want to get into anything like the CH ignition. The extra cost kind of defeats the purpose of converting your own. I'm planning on being at Shelby this year, so I'll probably see you then.

Jim

w8ye

My Feedback: (16)

Good job,

Be fore-warned that there are actually a lot of diferences in Homelite 25's and/or 30's

The 30's cylinder is most likely held on with #12 self thread rolling torx screws. While the 25 has #10's

The electric version has a compression release on the intake side as well as the EGR port on the exhaust side.

On the crankcase, the deck heights, and the position of the back plate flange varies by a pretty good tolerence.

Some back plates are steel.

you can use either the tapered seat or the gasketed plug in them. They seem to run the same with either.

see you there

Jim

Joe Petro

My Feedback: (1)

This is a must have for any homey conversion.
It rotates the carb so that the throttle linkage is a straight shot to the carb. No more bellcranks!
Zenoah sells it for 20 bucks, but if you are real nice, I'll give you the Homelite part number.

Ok, I guess you deserve to save over $17.00...

Homelite part # 06445 Heat Dam $2.65

If there is any interest, I'll post a pic of the adapter mounted.


Joe Petro

Tmoth4

My Feedback: (1)

Joe,
Where are you getting this part? Are you ordering directly from Homelite? or what?

Joe Petro

My Feedback: (1)

I just went to my local small engine repair place.
Anyone that services Homelite or John Deere can get it.


Joe Petro

Tmoth4

My Feedback: (1)

OK, Thanks.
Jim

w8ye

My Feedback: (16)

Jim,

If you get static about the insulator from your local repair shop, you can order it from Dave Carr. His is already bored out for the bigger carb.

Some of the local shops get real uppitty about selling their parts to some crazy jerk that is going to make an airplane engine out of a string trimmer.

I bought mine at a local shop. But I stopped at another near the Willard flying field and they had to have some number of the trimmer that wasn't the model number? I figured they were nuts and went back to the first dealer and ordered another.

These insulators will work pretty good on a bigger carb even if you do not bore them out according to Dave Carr.

After having two of them, I went back to the original kind and use a belcrank.

The Electric start insulator, when bored out has a very thin place on one side that introduces a vacuum leak.

I never got one from Dave but was talking to him about all this. That's when he started to sell them.

Good luck,

Jim

Tmoth4

My Feedback: (1)

Jim,
I did go ahead and order the adapter along with the big carb from Dave Carr. I was just curious about where to get homelite parts. He says (on his site) that this adapter is thinner than the stock one, so tha carb won't stick out as far, which is good news to me. I can't wait to try the big carb on it.

Jim

w8ye

My Feedback: (16)

Jim, when you get this going and adjusted, you will wonder how you ever got along without it. It makes the Homelite come alive from the way it was.

It would be better if you kept the rpm more towards 7,000 than towards 8,000 according to everything I have read. The Wolf Predator I have will turn a 18-8 at 8000 but I cannot remember right off what the Homelite 25 did. I know it did 7000 even with the stock carb and 16-10 but I cannot remember what it did after I changed it?

Jim

Tmoth4

My Feedback: (1)

Jim,
I was just looking at the carb on a stock homey I have and the throat is tiny! The bigger carb has gotta be better.
I'm not after high revs, just a little more guts.

Jim

w8ye

My Feedback: (16)

Jim,

If you have a Walbro carb there's a little number inside on the edge of the venturi as seen from the outside. It should be a 20 on the stock carb. On Dave Carr's carb, it will have a 28. The 20 means a 5/16" venturi and the 28 means a 7/16" venturi and a 32 would indicate a 1/2" venturi. Personnally I think the 7/16" is plenty big for either the 25cc or the 30cc engine.

If you have a Zama carb there will not be any numbers in there to see. But now that you know what sizes you want, perhaps you can measure your Zama. The only thing wrong with Zama's is that they don't have that little number in them. Another difference in the Zama is that on the ones with a butterfly choke, the inlet of the carb is not the same all around. There is a built up place on the blind side of the butterfly choke. I don't know that this hurts anything?

Another thing about these little carbs is that you can have two carbs with the same size venturi but one will have a bigger butterfly in it than the other.(where the carb fastens onto the carb insulator), The hole in the carb that the air goes through will be bigger or smaller. This is usually evident when you compare carbs from a Homelite 25 and a Ryobi. Both carbs have the same size venturi but the throttle bore is bigger on the Ryobi carb. That is only a phenominon and I doubt if there is any difference in the way they perform.

Enjoy,

Jim

Tmoth4

My Feedback: (1)

Jim,
Well, here's one for ya. The newer 25cc has number 24 stamped inside, and sure enough, your right, the opening is small, but the butterfly is bigger. And also, there is no idle mixture screw and the throttle has detents for three positions, just like the choke butterfly.

The older 30cc has number 20 stamped inside and has a smooth throttle movement like the older 25cc ones I have.

What do these guys do, change the design every week just for the fun of it?

Jim

w8ye

My Feedback: (16)

Jim

The McColluch 32 engines had a funny looking "24" carb on them as you describe. But I tried one on a Homelite 30cc and There wasn't enough improvement to measure over the "20" carb.

The "32" carbs (1/2") that I have, there is almost no venturi to them. The venturi area is only ever so slightly smaller than the throttle bore.

Jim

flying2bill

My Feedback: (2)

FYI Quadra 35 carb and flywheel will bolt right on the homey, I know this because I wore out a Q35 an put the pieces on my homey, havent tached it but turns a 18-6 quite nicely

Antique

My Feedback: (4)

The number in the venturi is the size in 64ths....

Tmoth4

My Feedback: (1)

I wondered what the numbers were. Milimeters were too big.

w8ye

My Feedback: (16)

Yes

Yes, I wondered that too several years ago and came up with all this metric flow rate. (wrong). The only chain saw place I found around here that the guy even knew what I was talking about, didn't know what it ment either but he knew a 28 was bigger than a 20. Ralph Set me straight on it a couple years ago. But I keep getting it messed up and think its 32nd's (wrong). I had made some posts on here relating to size in 32nds and then I read some of Ralph's posts in a search and noticed it was 64ths. So I went back and corrected the ones I could recently think of the night before rcign made the post above.

I think they change the model # everytime they come back from break. That's the way all Japanese stuff is. They do consistantly make certain models though. The Weed Whacker people are the ones that keep changing the carbs. They will mix and match between Zama and Walbro as well as all variations thereof.

Jim

Flyguy2002-RCU

My Feedback: (1)

http://webpages.charter.net/rsengineconversions/

These guys really know their stuff and they can provide complete motors or conversion/upgrade parts. Look em up.

I have one of their homelites on my Ultra Stick and it runs like a scaleded dog.

Big al