I am about to start my first large model.Operating on a tight budget,I note that modellers have used brushcutter,or strimmer engines
(UK),to power large models for a fraction of the cost of purpose - made engines.Does anyone have comments regarding
output shaft size,mixture at altitude,mounting etc.?
Would appreciate any info
Regards to all.
Glowplug55

Typically, these engines are converted using the flywheel end as the output shaft as most flywheel ends of trimmers/brushcutters turn counterclockwise.

The threads on the flywheel end of the crankshaft is usually 8mm

You need a carb with both a high speed and a low speed mixture adjustment. Often a larger carb is used from what was on the original engine.

The mixture adjustment is for the prop load on the engine and not for altitude adjustment as these carbs all have altitude compensators.

Blower engines often turn the opposite direction so they have to be reversed or use the opposite end of the engine in some cases.

Stihl trimmer/brushcutters

<table cellspacing="1" cellpadding="3" border="0" width="641"> <tbody> <tr class="footertext"> <th bgcolor="#ffb060" width="12%"> <p class="footertext">MODEL</p> </th> <th bgcolor="#ffb060" width="22%"> <p class="footertext">DISPLACEMENT</p> </th> <th bgcolor="#ffb060" width="22%"> <p class="footertext">ENGINE POWER</p> </th> <th bgcolor="#ffb060" style="width: 22%;"> <p class="footertext">WEIGHT (LBS.)</p> </th> <th bgcolor="#ffb060" width="22%"> <p class="footertext">FUEL CAPACITY</p> </th> </tr> <tr bgcolor="#ffb060"> <td align="center" colspan="5" class="bold">Occasional Use Trimmers</td> </tr> <tr bgcolor="#cccccc"> <td class="footertext"> <p class="footertext">FS 40 C-E</p> </td> <td class="footertext"> <p class="footertext">27.2 cc (1.66 cu. in.)</p> </td> <td> <p class="footertext">0.7 kW (0.9 bhp)</p> </td> <td style="width: 19%;"> <p class="footertext">4.5 kg (9.9 lbs.)</p> </td> <td> <p class="footertext">340 cc (11.5 oz.)</p> </td> </tr> <tr> <td class="footertext">FS 45</td> <td class="footertext">27.2 cc (1.66 cu. in.)</td> <td class="footertext">0.75 kW (1.01 bhp)</td> <td class="footertext" style="width: 19%;">4.1 kg (9.0 lbs.)</td> <td class="footertext">330 cc (11.2 oz.)</td> </tr> <tr> <td bgcolor="#cccccc" class="footertext"> <p class="footertext">FS 46</p> </td> <td bgcolor="#cccccc" class="footertext"> <p class="footertext">27.2 cc (1.66 cu. in.)</p> </td> <td bgcolor="#cccccc"> <p class="footertext">0.75 kW (1.01 bhp)</p> </td> <td bgcolor="#cccccc" class="footertext" style="width: 19%;"> <p class="footertext">4.2 kg (9.3 lbs.)</p> </td> <td bgcolor="#cccccc" class="footertext"> <p class="footertext">330 cc (11.2 oz.)</p> </td> </tr> <tr> <td class="footertext"> <p class="footertext">FS 55 R</p> </td> <td class="footertext"> <p class="footertext">27.2 cc (1.66 cu. in.)</p> </td> <td class="footertext">0.75 kW (1.01 bhp)</td> <td class="footertext" style="width: 19%;">4.8 kg (10.6 lbs.)</td> <td class="footertext">330 cc (11.2 oz.)</td> </tr> <tr> <td bgcolor="#cccccc" class="footertext"> <p class="footertext">FS 56 C-E</p> </td> <td bgcolor="#cccccc" class="footertext"> <p class="footertext">27.2 cc (1.66 cu. in.)</p> </td> <td bgcolor="#cccccc" class="footertext"> <p class="footertext">0.8 kW (1.1 bhp)</p> </td> <td bgcolor="#cccccc" class="footertext" style="width: 19%;"> <p class="footertext">5.2 kg (11.5 lbs.)</p> </td> <td bgcolor="#cccccc" class="footertext"> <p class="footertext">340 cc (11.5 oz.)</p> </td> </tr> <tr class="footertext"> <td class="footertext">FS 56 RC-E</td> <td class="footertext">27.2 cc (1.66 cu. in.)</td> <td class="footertext">0.8 kW (1.1 bhp)</td> <td class="footertext" style="width: 19%;">4.8 kg (10.6 lbs.)</td> <td class="footertext">340 cc (11.5 oz.)</td> </tr> <tr bgcolor="#cccccc" class="footertext"> <td class="footertext">FSE 60</td> <td class="footertext">120 volt (60 Hz)</td> <td class="footertext">600 Watts (5.3 amps)</td> <td class="footertext" style="width: 19%;">4.0 kg (8.8 lbs.)</td> <td>-</td> </tr> <tr bgcolor="#ffb060"> <td align="center" valign="top" colspan="5" class="bold">Professional Use Trimmers &amp; Brushcutters</td> </tr> <tr> <td bgcolor="#cccccc"> <p class="footertext">FS 70 RC-E</p> </td> <td bgcolor="#cccccc"> <p class="footertext">27.2 cc (1.66 cu. in.)</p> </td> <td bgcolor="#cccccc"> <p class="footertext">0.9 kW (1.2 bhp)</p> </td> <td bgcolor="#cccccc" style="width: 19%;">

<span class="footertext">4.8 kg (10.6 lbs.)</span></p> </td> <td bgcolor="#cccccc"> <p class="footertext">340 cc (11.5 oz.)</p> </td> </tr> <tr> <td> <p class="footertext">FS 90 R</p> </td> <td> <p class="footertext">28.4 cc (1.73 cu. in.)</p> </td> <td> <p class="footertext">0.95 kW (1.27 bhp)</p> </td> <td style="width: 19%;">

<span class="footertext"> 5.3 kg (11.7 lbs.)</span></p> </td> <td> <p class="footertext">530 cc (18.0 oz.)</p> </td> </tr> <tr bgcolor="#cccccc"> <td class="footertext">FS 90</td> <td class="footertext">28.4 cc (1.73 cu. in)</td> <td><span class="footertext">0.95 kW (1.27 bhp)</span></td> <td style="width: 19%;"><span class="footertext">5.5 kg (12.1 lbs.) </span></td> <td><span class="footertext">530 cc (18.0 oz.)</span></td> </tr> <tr> <td> <p class="footertext">FS 100 RX</p> </td> <td> <p class="footertext">31.4 cc (1.9 cu. in.)</p> </td> <td> <p class="footertext">1.05 kW (1.4 bhp)</p> </td> <td style="width: 19%;"> <p class="footertext">4.9 kg (10.8 lbs.)</p> </td> <td> <p class="footertext">530 cc (18.0 oz.)</p> </td> </tr> <tr bgcolor="#cccccc"> <td> <p class="footertext">FS 110 R</p> </td> <td> <p class="footertext">31.4 cc (1.9 cu. in.)</p> </td> <td> <p class="footertext">1.05 kW (1.4 bhp)</p> </td> <td style="width: 19%;"><span class="footertext"> 5.5 kg (12.1 lbs.) </span></td> <td> <p class="footertext">530 cc (18.0 oz.)</p> </td> </tr> <tr> <td class="footertext">FS 110</td> <td><span class="footertext">31.4 cc (1.9 cu. in.)</span></td> <td><span class="footertext">1.05 kW (1.4 bhp)</span></td> <td style="width: 19%;">

<span class="footertext"> 5.8 kg (12.8 lbs.)</span></p> </td> <td><span class="footertext">530 cc (18.0 oz.)</span></td> </tr> <tr> <td bgcolor="#cccccc"> <p class="footertext">FS 130 R</p> </td> <td bgcolor="#cccccc"> <p class="footertext">36.3 cc (2.2 cu. in.)</p> </td> <td bgcolor="#cccccc"> <p class="footertext">1.4 kW (1.9 bhp)</p> </td> <td bgcolor="#cccccc" style="width: 19%;">

<span class="footertext">5.6 kg (12.3 lbs.)</span></p> </td> <td bgcolor="#cccccc"> <p class="footertext">530 cc (18.0 oz.)</p> </td> </tr> <tr> <td><strong class="footertext">FS 130[/b]</td> <td><span class="footertext">36.3 cc (2.2 cu. in.)</span></td> <td><span class="footertext">1.4 kW (1.9 bhp)</span></td> <td style="width: 19%;"><span class="footertext">5.9 kg (13.0 lbs.) </span></td> <td><span class="footertext">530 cc (18.0 oz.)</span></td> </tr> <tr> <td bgcolor="#cccccc"> <p class="footertext">FS 250 R</p> </td> <td bgcolor="#cccccc"> <p class="footertext">40.2 cc (2.45 cu. in.)</p> </td> <td bgcolor="#cccccc"> <p class="footertext">1.6 kW (2.15 bhp)</p> </td> <td bgcolor="#cccccc" style="width: 19%;">

<span class="footertext"> 6.0 kg (13.2 lbs.) </span></p> </td> <td bgcolor="#cccccc"> <p class="footertext">640 cc (21.6 oz.)</p> </td> </tr> <tr> <td><span class="footertext">FS 250</span></td> <td><span class="footertext">40.2 cc (2.45 cu. in.)</span></td> <td><span class="footertext">1.6 kW (2.15 bhp)</span></td> <td style="width: 19%;"><span class="footertext"> 6.3 kg (13.9 lbs.)</span></td> <td><span class="footertext">640 cc (21.6 oz.)</span></td> </tr> <tr> <td bgcolor="#cccccc"> <p class="footertext">FS 310</p> </td> <td bgcolor="#cccccc"> <p class="footertext">36.3 cc (2.2 cu. in.)</p> </td> <td bgcolor="#cccccc"> <p class="footertext">1.4 kW (1.9 bhp)</p> </td> <td bgcolor="#cccccc">

<span class="footertext"> 7.2 kg (15.9 lbs.) </span></p> </td> <td bgcolor="#cccccc"> <p class="footertext">710 cc (24.0 oz.)</p> </td> </tr> <tr bgcolor="#ffb060"> <td align="center" valign="top" colspan="5" class="bold">Forestry Brushcutters &amp; Clearing Saws</td> </tr> <tr> <td><span class="footertext">FS 360 C-E</span></td> <td><span class="footertext">37.7 cc (2.3 cu. in.)</span></td> <td><span class="footertext">1.7 kW (2.3 bhp)</span></td> <td style="width: 19%;"><span class="footertext">8.5 kg (18.7 lbs.)</span></td> <td><span class="footertext">750 cc (25.4 oz.)</span></td> </tr> <tr> <td> <p class="footertext">FS 460 C-EM</p> </td> <td> <p class="footertext">45.6 cc (2.8 cu. in.)</p> </td> <td> <p class="footertext">2.2 kW (3.0 bhp)</p> </td> <td><span class="footertext">8.5 kg (18.7 lbs.)</span></td> <td> <p class="footertext">750 cc (25.4 oz.)</p> </td> </tr> <tr> <td bgcolor="#cccccc"> <p class="footertext">FS 550</p> </td> <td bgcolor="#cccccc"> <p class="footertext">56.5 cc (3.45 cu. in.)</p> </td> <td bgcolor="#cccccc"> <p class="footertext">2.8 kW (3.75 bhp)</p> </td> <td bgcolor="#cccccc" style="width: 19%;"> <p class="footertext">10.0 kg (22.0 lbs.)</p> </td> <td bgcolor="#cccccc"> <p class="footertext">755 cc (25.5 oz.)</p> </td> </tr> </tbody></table>

The Stihl engines are good ones for sure, but in general harder to find used than the other brands. Echo is another excellent engine, and somewhat more commonly found. They are from 21 to 25cc in the brush cutter/weedeater sizes.

Other good choices are Homelite 25/30cc engines, and the Ryobi 30/31cc. These make good airplane engines, though they are a bit heavier and not as powerful as the Echo engines.

All in all, my favorites are the Echo engines. Two examples:

One of my Echo engines is all "hopped up" with porting mods, etc., but it turns an APC 16 x 8 prop at 9400 rpms, weighs only 2 lbs. 9 oz. complete, and creates over 15 lbs. of static thrust.
Another one, that only has a slightly larger carb and a modified free breathing muffler turns a Top Flite 18 x 6 prop at 7500 rpms and creates nearly 15 lbs. of static thrust at a much lower pitch speed. The "hot rod" engine pulls a 72" wingspan Katana around like a rocket, and the milder Echo flies a 60" wingspan Fokker Triplane just beautifully.

Once again, this is a generality, but I have found a good airplane size for the weedeater engines to be from a low of 1000 square inches of wing area and 9 to 10 lbs. to a high of around 1200 inches and maybe 15 lbs. (There are exceptions of course.)

If you have welding and machining abilities, you can make your own mufflers and prop hubs. Most of my mufflers are just "gutted" and modified stock mufflers. You will have to decide if you want to keep the magneto, or convert to electronic ignition. I nearly always convert to electronic ignition for lighter weight, easier starting, and somewhat more power.

Sources for prop hubs, parts, etc.:
www.lambertsrc.com
www.wackerengines.com
www.carrprecision.com
www.southeastrcengines.com
www.valleyviewrc.com
www.milehighrc.com

(The last three are for ignitions.) Here is some other "food for thought" about ignition systems: http://www.rcuniverse.com/forum/m_80...tm.htm#8009384

Good luck. It is a fun (and cheap) hobby converting engines.

AV8TOR

Look at the sticky at the top of the page

You will probably end up with better engines than most China buit ones...except for DLE engines. Capt,n

( but ) if you need to purchase the conversion parts , ignition and the trimmer your cheapest rout would be the chinese purpose built if the cost is the factor. If you want a very good reliable build your own for what you want.

Captn I am still waiting for you and your wife to make it to Houston area.

Well, I don't know about that. Admittedly the DLE engines are good, and the price is pretty low, but...

Score an Echo trimmer from the trash or from the discard pile at a small engine repair shop for free.

RCEXL Ignition = (Let's say 70 bucks, though you can sometimes find them for 50$.)
Prop hub = 20 bucks.
Muffler = Gut the stock one and have some 1/2" tubes welded in. (Let's say 10 bucks for the welding)
Larger carb = 10 bucks used from the small engine shop, plus 8 bucks for a rebuild kit = 18 bucks. (New ones are often available on e-bay for as little as $20.00 as well.)
And let's just say we decide to put a new, high quality piston ring in it from Frank Bowman too. = $11.00

So, we're at $129.00. If you had to pay 20 dollars for the engine, you still come in at under $150.00, with a quality ignition system, a new ring and a rebuilt carb. The cheapest DLE is $269.00. And by converting the engine yourself, you have the intimate knowledge of the engine itself, the gratification of having done it yourself, and the fun of telling people you have a "weed whacker engine" flying your plane! Works for me! But watch out, once you start doing this and letting people know you are looking for old yard equipment, before you know it you will probably have a whole PILE of engines!

If you decide to stick with the original magneto, then you can actually do a gasser engine conversion for less than $100.00. Some airplanes, like World War 1 planes need heavy engines, so in that case leaving the magneto on is a good option.

AV8TOR

I agree 100%, I was just concidering buying new trimmer or saw to start with all new parts but going used is cheaper unless it gives you that disease and can't stop the conversion craze

Oh yeah, I've got the "disease" alright. BOXES of engines!

AV8TOR