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Jan 17, 2009, 08:03 PM
"Superior Air Power"
War Bird Radio's Avatar
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Discussion

Yet another weedeater engine conversion


I've decided to do a conversion on my old weedeater. I got it for free a few years ago and it was a few years old then. It started running bad and finally wouldn't run at all last year and I noticed it wasn't getting fuel through the carb. I took it into a small engine repair shop when I had my chain saw sharpened, they guy said it wasn't worth even rebuilding the card since parts and labor would be close to what a new weedeater costs. Ok, so I bought a new weedeater and tossed the old one in to our junk trailer.

Well, I've been inclined to drag the old weedeater out of the junk trailer to see if I can convert it for R/C use. From what I've read on line it's not too difficult.

The weedeater is branded Craftsman and is 25cc but I don't know who made it. Can someone tell by looking at the pics who made it? This will help in finding conversion parts.

I have the engine torn down except for the case, crank and flywheel. I removed the short shaft from the front of the flywheel but how does the fly wheel come off? Is it pressed on and keyed? Or is it threaded? The motorcycles I've worked on had the flywheel keyed to the shaft but this little flywheel seems to be really stuck on.

And when when tearing down the engine I almost got stung, seems some hornets decided this was a good place to hibernate.

Thanks,
John
Last edited by War Bird Radio; Jan 21, 2009 at 11:54 AM.
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Jan 18, 2009, 10:01 AM
Registered User
Look here.
http://www.rcuniverse.com/forum/forumid_92/tt.htm
Jan 18, 2009, 08:34 PM
"Superior Air Power"
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I've found that this is a Homelite 25cc enigne. Have started to cut excess metal from the case. The bearings will need to be replaced since I can't help getting metal dust in them.

Anyone know where to get Homelite parts?

John
Jan 19, 2009, 10:46 AM
Registered User
Quote:
Originally Posted by War Bird Radio
Anyone know where to get Homelite parts? John
You could try Your local chain-saw shop.

I've also bought parts off ebay and the internet.
Do a google search.

Get a new ring and seals while Your at it.
Good luck.
Jeff
Jan 19, 2009, 02:41 PM
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andernamen's Avatar
I've converted this same engine and it runs very well, and isn't too heavy. BUT, it really isn't suited to a warbird without quite a bit of work to lighten it up. I ended up spending quite a bit more in the end than if I had bought a new chinese made model engine. The engine was free, I got an EI system for about $60, timing kit with prop hub and magnet from CH for $60, a new carb for the G26 for $55, mount and muffler from wacker engines for $60. You can buy a new engine for around $240. Depending upon what you need the engine for, and how much of the work you can do yourself, you may just want to buy a new one.
Jan 20, 2009, 09:11 AM
"Superior Air Power"
War Bird Radio's Avatar
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MrGreen,
Yep, I found the local Small Engine Shop has parts. Just thought that there was a ready on line source. I've done a little searching on the net but can't really tell who has what.

Ring and seals, that's exactly what I'm after.

andernamen,
I plan on using the mag ignition but will change the Zama carb or a Walbro, add a velocity stack, upgrade the muffler and buy a prop hub. Shouldn't have too much into it. Will be flying a funfly type plane.

Will post pics of progress soon.

John
Last edited by War Bird Radio; Jan 21, 2009 at 11:41 AM.
Jan 20, 2009, 09:17 AM
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andernamen's Avatar
War Bird Radio,

It should be great for that and won't cost too much either. Wacker engines has all the basic conversion parts for this engine, and it is easy to do. You can try a variety of Walbro carbs with a 11.1 mm venturi, but finding one that will work well with a low idle, can be a challenge. That is why I ended up buying the walbro off of the G26. It works great and there is no tweaking to be done. Just bolt it on and go.
Jan 21, 2009, 11:26 PM
"Superior Air Power"
War Bird Radio's Avatar
Thread OP
Progress report:
Case; extra metal cut and ground off.
Case, cylinder & mag bead blasted.
New bearings installed in case.
Mag machined.
Cut plastic backplate.
Partial assembly.

The photos show the difference between an unmodified and modified case. You can also see the flywheel modification.

Still need to rebuild a carb, get or make a suitable muffler, make engine mount and fabricate a prop hub.

So far total expenditures is $31 for bearings.

John
Last edited by War Bird Radio; Jan 21, 2009 at 11:32 PM.
Jan 22, 2009, 07:03 PM
RCAPA #299
jg4660's Avatar
It's coming along.....looks good.
Jan 22, 2009, 07:54 PM
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Broken Wings's Avatar
Very Nice work. What are you thinking about putting it in?
Jan 22, 2009, 11:34 PM
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Thanks guys!

Not sure what to put it in yet. The question is should I buy a kit or build from scratch?
I thought to use up some coroplast we have sitting around here and make a SPAD. The idea is to keep in inexpensive. Or mabey a pink foam funflyer like Crazy Herb built. Also have plans for a 40" sport flyer that I thought about enlarging 100%, it would be a conventional build. I'm open for suggestions.

Right now I'm focused on getting the motor going. Still have to locate my tach for the testing phase.

John
Jan 23, 2009, 07:43 AM
<>< AKA W4BPS

Walbros


If you watch fleabay you can get some pretty good deals on walbro carbs. I bought a 644 for my G26 for $16 brand new. I bought another new one for my G23 for $21. Just a thought. Brian
Jan 23, 2009, 08:59 AM
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Speaking of carbs, do they usually leave the choke butterly and primer bulb on when using the stock carb?
Also, I heard about modifing the carb by enlarging and polishing the intake. anyone done this?

John
Jan 24, 2009, 01:33 PM
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Hope in the next week or two to have a motor mount, prop hub and spinner machined out of aluminum. This will keep the cost down, just a little time, effort and material.
Jan 24, 2009, 07:17 PM
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Broken Wings's Avatar
Try a Bridi kit. http://www.bridiairplanes.com/hangar/bridistick.html

I'm just finishing one up and it was a pleasure to build. All machine cut and sanded parts, went together with wood glue.

For the price, it's almost a Balsa Spad.....


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