WeedEater conversion questions

[Strato911]

After flying for about 9/10 years with smaller planes using Nitro fuel,
I'm now interested in building a larger plane with a less costly fuel
(gasoline). I have seen numerous sites with instructions for converting
weed trimmer engines for aircraft use, but they usually recommend against
using the WeedEater engines. I would prefer to use a Ryobi engine as
suggested, but they are very uncommon in my area (Winnipeg Canada). I
couldn't even find one without buying a complete unit, and few places
sell/service them. Princess Auto has refurbished WeedEater engines for $60
Canadian.

My questions are: Has anyone here performed the conversion on a 25cc
WeedEater? How were the results (are you happy with it)? What size prop
would you recommend for this engine? And, are there any particular steps I
should watch out for?

Any help / suggestions would be greatly appreciated.

Strato911
(remove <NoSpam> if replying directly)

[Robert Bauer]

In my very limited knowledge as far as I know, the 25cc conversions are about
the bottom of the HP to weight ratio. It will definitely depend on the weight
and type of the plane you want. A friend at the field had a 25 in a design of
his own similar to the Sr. Telemaster that would not get off the ground. He
then put a 32cc in and the plane flew good. At the cost and trouble of
converting compared to an engine designed for our use I think I would look for
something other than a conversion. I am sure others will be able to help more
however that is my $0.02 worth.

"Strato911

[Edwin Smith]

I just got finished doing the ryobi conversion. I used jag conversion
parts, bolted right on with know problem. The conversion was relatively
easy. The only hard part was turning down the cooling fins on the fly
wheel. A buddy with a lathe did it for me. I'm just now finishing up a
test stand and will try to start it tonight. I also made sure it ran
before I converted it, since it was given to me for free as a broken engine.
It only needed a walbro pump diaphram and to fix the spark plug clip in the
wire's cap. It had walloed out and didnt make good connection. Ran great
as a weedie. I know of others in our club that have modified a 25cc engine
with success.
Edwin

"Strato911 @hotmail.com>" <strato911<NoSpam> wrote in message
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[Strato911]

Unfortunately I haven't been able to find a conversion kit for the
WeedEater brand, since Ryobi seems to be scarce here. Any links to
conversion websites would also be appreciated.

Strato911

"Edwin Smith" <edwin....@compaq.com> wrote in message
news:tW4g9.1$qR6.1...@news.cpqcorp.net...

[Edwin Smith]

These are the 2 that I found.
http://webpages.charter.net/rsengineconversions/
http://www.jagengines.com/
RS Engines does a Homelite 25cc conversion.
Edwin

"Strato911 @hotmail.com>" <strato911<NoSpam> wrote in message

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[Strato911]

These sites only sell conversions for the Ryobi, and Homelite. Are you
trying to say they are the same regardles of the engine manufacturer? I
find that hard to believe...

Strato911

"Edwin Smith" <edwin....@compaq.com> wrote in message

news:ox5g9.2$IS6.1...@news.cpqcorp.net...

[Edwin Smith]

I'm a little confused. Same what! Conversions can be applied differently
but basically have the same end result. You can buy conversion parts for
the ryobi from both vendors. They will look different, but just in
application. Basically, all you have to do is come up with a prop hub,
motor mount, and reduce the weight of the engine. Anything else is to
customize to your application, carb position, different muffler and so on.
They wont be the same as a gasser specifically made for RC. A gasser
specifically made for RC would have a better balancing on the crank, better
rings on the piston, less metal on the cylinder, generally lighter in
weight. Thats pretty much the bulk of what I know. Will have practical
experience in a couple of weeks. There is a giant scale engines forum on
www.rcuniverse.com that will have tons of info. I imagine some parts would
work on other engines, dont which. Try them for what works where.
Edwin

"Strato911 @hotmail.com>" <strato911<NoSpam> wrote in message

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[David AMA40795 / KC5UH]

Here's another site....

http://www.carrprecision.com/Pages/prod02.htm

David

[Charles Wahl]

In article <kO5g9.2360$i%.582444@localhost>, "Strato911"
<strato911<NoSpam>@hotmail.com> wrote:

> These sites only sell conversions for the Ryobi, and Homelite. Are you
> trying to say they are the same regardles of the engine manufacturer? I
> find that hard to believe...

I think if you did enough research, you might find that WeedEater's
engines are made by someone else, and might be identical to something that
other people call by a different name.

I think that, generally speaking, a 25cc engine is a bad deal from a
power-to-weight standpoint. You will probably find that it weighs 4 pounds
or more without a muffling system. Several of the 50cc engines weigh the
same, with almost twice the power. You'll have to do a lot of work to
convert it. The magneto ignition system is heavy, and also has a fixed
timing (advance does not vary with rpm) so you either have to de-tune the
high end, or have something that may be a bear (and even dangerous) to
start.

Most of the commercially available model gas engines are really just
conversions of a block designed to power something else. Some of these
conversions are rather sophisticated, and others are not.

I'm not trying to dissuade you -- I have a converted Poulan chainsaw
engine, 46cc, and am very happy with the result. I'd just look for a
larger displacement block. The Ryobi (31cc) is about the minimum for
powering something like a quarter-scale Cub. These are available as
reconditioned trimmers from Harbor Freight (www.harborfreight.com) for
about $60US. See some of the excellent pages on conversion:

http://www.geocities.com/CapeCanaveral/Hangar/1071/ryobi.htm
http://www.geocities.com/CapeCanaveral/Lab/6216/sonof.html
http://www.reivers.myweb.nl/ryobimods.htm

One person who does custom conversion work (or can make parts for you like
prop adapter, ignition system with advance, etc.) is Ralph Cunningham of
RCIgnition (www.rcignition.com).
--
Charles Wahl <cfw...@earthlink.net>

[Strato911]

Just to re-itterate - I am looking for people who have performed the
conversion to a WeedEater® engine who can provide feedback / advice.

Thanks for the links. However, I have already visited them. They all
refer to the Ryobi engine. As I have mentioned previously, the Ryobi is
hard to obtain locally, so I have already purchased the WeedEater engine
(made by Poulan.), so that's what I have to work with. The intended plane
is of my own design, and will be designed to fit the engine and it's
performance. If this works out, then I will try again with a larger engine.
My main reason for this is to save $$$$. The aircraft engines would cost me
upwards of $500 Canadian, while this is estimated to be $250 - $300
(Canadian) by the time I am done.

"Charles Wahl" <cfw...@earthlink.net> wrote in message
news:cfwahl-1209...@dialup-209.246.70.71.dial1.newyork1.level3.net.
..

[Paul McIntosh]

Well, if you would have checked before buying the engine, you would have
know that the Poulan is not a popular conversion. You are pretty much on
your own on this one.

The biggest headaches with these engines are the magneto ignition and prop
adapter. C&H makes great ignition systems for smaller engines. Give them a
ring and see what they can do for you. Next, check with a local machine
shop and see if they can make a prop adapter to fit the Poulan shaft.

It also couldn't hurt to call the other conversion folks and see what they
can do for you. Maybe they have parts that will fit your engine as well as
others.

"Strato911 @hotmail.com>" <strato911<NoSpam> wrote in message

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[Strato911]

This thread was meant only for those who HAVE converted a WeedEater®
engine, or know someone who has.

I did research it first. I have to deal with what is available. Cost on
a Ryobi trimmer here is double what the others cost, and EXTREMELY RARE.
No-one wants to service them either. I have stated this time and again.

Strato911

"Paul McIntosh" <pa...@mcintoshcentral.com> wrote in message
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[Paul McIntosh]

I guess you haven't got the picture yet. It seems that NO ONE has converted
one for the many reasons given. You are on your own.

"Strato911 @hotmail.com>" <strato911<NoSpam> wrote in message

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[Strato911]

To relieve your confusion regarding what's meant by "the same". I meant
are the thread sizes and spacing the same? Will a prob hub for a Ryobi fit
a WeedEater®? Will the bolt pattern of a Ryobi engine mount work for the
WeedEater®? And similar compatability questions.

I just joined www.rcuniverse.com last night (before I read your reply),
and have gained significant knowledge on the matter. Their forums are quite
extensive, and extremely thorough. Somethimes too thorough...

I realize that a converted string trimmer / chainsaw engine isn't quite
the same as one designed for RC aircraft use, but as I mentioned previously,
this is an attempt to keep my costs down. I can't justify $500-$800 (Can)
for an engine when I only get time to fly about 10-20 flights a year.

Thanks again to all those who replied with usefull info / links.

Strato911

"Edwin Smith" <edwin....@compaq.com> wrote in message

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