Hi. I have this weed eater (homelite z625cd), and I want to convert its engine for rc airplane use. I read in this forum that there are hundreds of pics and guides available, however I can find a guide or how to from the start. I don't know even how to get this thing off the weed eater structure. Is there such thing as a complete guide on this conversion? Or can anyone guide me on this? Thanks!

rinoldi,
If you lack mechanical ability, you may want to buy a ready made conversion off the RCU classifieds. Engine conversion isn't for everyone.

Dave

Some engines are more conversion-friendly than others. Check Carr Presision online. They have kits and helpful instructions for doing your own conversion.

Dr.1

I didn't lack mechanical abilities, it only happens that I never did something like this before.
Also, there is no guide or anything in Carr's website. If someone can point me to a site that explains HOW TO CONVERT A HOMELITE 25cc engine for RC flying, it will be very appreciated.

I usually start by taking the weed eater parts off.

Bill

there really isnt one. most of us kinda piece together what others before us have done before.

1. start by removing plastic from the weedeater.

2. trim down the backplate (which is the only plastic you keep)

3. trim down the fins on the magneto wheel.(either by lathe or hacksaw them but that takes rebalancing)

4. trim down the flashing from the crankcase that you dont need. (be careful not to remove your mount for the magneto)

5. get a prop hub by either buying one or making one for yourself. (carr carries this)

6. get an engine mount which bolts on top of the trimmed down plastic backplate.(carr again carries them)

7. get a 16 to 18 inch prop

8. there might be a blowback hole on the exhaust port drill this and tap it for 10/32 becareful not to drill or tap so far you go into the piston wall. put a small allen head set screw in the whole you just tapped.

9. take the muffler apart strip out the guts but keep the metal posts those keep the muffler intact when you tighten the muffler.

10. this step is not always necsesary but get a bigger bore carberator. ( the stock might be a 9mm venturi which means less fuel, stock carb might not be adjustable as well)

11. plug the metal tube that comes from the priming bulb on the carb since you might not need it if you use an electric starter. then connect your fuel feed line to the other brass tube. also this might be a good time to tell you that the carb spacer needs trimming.

12. mount on a very sturdy stand these engines reguardless of what you heard have some amount of power.

13. you can use a standard electric starter and turn the engine over till it starts

14. any questions post them here and see where we can help.


also one side note the magneto pickup you need to either get a switch or use the one on the weedeater for you to kill the engine with or you will be doing what i did and hold the wire that the switch plugs to on the engine till it quick. i think the switch would be easier or you can just clip the fuel line.

ps you will have to get a torque set of drivers. those bolts that the engine is put together with are not allen heads something like this
http://www.harborfreight.com/cpi/cta...emnumber=91238

basically they have a star looking pattern on the head. if you ask someone at the hardware store and ask if they have torque drivers they will know what you are talking about.

Carlosponti, your answer was what I was needing!
Thanks a lot for your time; as you said I will ask again if I'm in trouble following any of those steps.
And yes, I did notice the torx bolts already, I have a set of torx drivers legacy of my computer and videogame console days (tha was way years before they invented RC flying! )

THANKS!

Those bolts were self tapping and had Loc Tite on them. The bolts are rather soft and will strip or break off at the head. Warm up the area where the threads are before you try to remove them to make the Loc Tite let go. Then they will come right out.

I always replace the original bolts with real Allen type socket head bolts. Some Homelites have 12-24 bolts holding the cylinder on. #12's are hard to find without paying a big price.

OK, rinoldi, here's what you do:

Buy your Homelite. Buy a Zenoah of similar displacement. Take everything off the Homey that the Zenoah doesn't have. Add what the Zenoah does have that the Homey doesn't.

See, it's easy.

BTW, I've done a couple and I didn't have instructions. They ran great. Of course, I had access to a lathe to custom-turn the prop drive shaft, too.

Dr.1

Hey! Could I borrow that lathe for a while? Capt,n

Yeah, Cap'n, I'll box it up and FedEx it to ya.

Actually, doing a conversion is easy. Simply cut off everything you don't absolutely need. If you don't have access to a lathe, Carr Precision will sell you a prop drive shaft.

Dr.1

I got my Homelite 25cc engine off a weed wacker. Then, I contacted www.wackerengines.com to get the appropriate prop adapter, muffler and back plate.
That's it! The thing works great on a Master Airscrew Classic 16 x 8". Idles at 2600 RPM and run full speed at 7500 RPM

It's installed in a Midwest Super Stearman. I'll fly it tomorrow!

Rinoldi, hows the conversion comming? I recently did a conversion on the blower version of this engine and had good luck with it. The ONLY thing I will caution you about is to not be hard on any of the parts during the disassembaly - specifically the shaft. In fact, leave the shaft in the case. I took mine out and used a hammer to tap it through the berings and damaged the threads on the tip of the shaft. I tried to cut the damaged threads off and start fresh but I just screwed it all up from there. I was able to get the nutt on (although it was stripped) and then welded it to the shaft to ensure it wouldnt come loose. The engine ran great. I dont know what the RPM's were but I was running a MA 18-6 and it really ran well. I had it in a giant scale float plane I am building (I had the fuselage assembled and the floats) and drove it around the pond a bit. It got right up on step and skipped across the water at 20mph (measured with GPS). However, the way I had the prop on there (welding the nutt) didnt work out real well in the long run, the prop came loose and there was no way to tighten it [:@]. So... now I need a new shaft (and flywheel, I trimmed mine but now I dont have anything to ballance it with).

I did my conversion with pretty crude tools. I had an abrasive cutoff blade on a circular saw (the kind used for ripping wood), a jig saw, files, and a drill. I used the circular saw to cut away the large mounting flage on the crank case. All I left of it is where the mount for the magneto is (leave BOTH parts of that connected to the crank case). Then I made a mount for the engine out of aluminum (1/8"x3/4" flat stock). I attached the mounts to the back plate of the engine. The screws that hold that plate on are 10-24 threads, so I got some longer ones that would go all the way through the mount I made and into the engine. Note= get a bolt that is slightly longer than you need and then screw the nutt on all the way to the head before you put the bolt through the mount and into the engine. This way you can tighten the nutt down inside the crank case as FAR as it will go (the crank case is pretty soft compared to the bolts, if only a 1/4" of threads are in you can pull the bolt right out of the hole). Then back the nutt into the mount and use that to tighten everything up.

If you want to see some of the pictures I have, go here: [link=http://www.rccanada.ca/bb/viewtopic.php?t=22717&sid=c8c2a0860c205a20b450d7f2 01ad503f]Homelite leaf blower engine conversion[/link]

Steve