Chainsaw Repair

Quote:
"Finally got around to finishing my Stihl 62cc out of an 036 chainsaw. It was a bit of a labor intensive conversion, but it turned out nice. Turns a Zoar 22 x 8 prop at 7400 rpms.

I had to make an intake manifold adapter to fit the oddball round intake port. My first idea was to use a homemade aluminum adapter, along with a spacer that used the carb mounting bolts. I was going to insulate the bolts themselves with shrink tubing, and use fiber washers under the heads at the carb, all to insulate it from heat. This didn't end up working too well, as the carb still got too hot. Also, that setup was too long to fit the cowl of my 28% Wild Hare Extra. So I milled down my aluminum adapter, and made a new insulator that bolted to the adapter, and had separate holes in it to mount the carb, thus properly insulating the carb. That setup works perfectly.

Of course cutting the engine out of the saw was a bit of a chore, but it really doesn't take too long when you get right down to it. Just be careful with those magnesium shavings and grindings....

I didn't want to use the tapered end of the crank, because it had a very small threaded end that I didn't trust to screw a prop adapter to. So I cut the other end of the crankshaft to length, then bored and tapped it for a stud. The prop adapter screws onto that stud, and seats against the shoulder where the stud screws into the crankshaft. The prop adapter extends back over the crankshaft in that area, and is also supported by radially placed set screws. The crank is a real "bear" to work with, as it is super, super hard. Anyway, I then cut the tapered end of the crank off right at the bearing, and made a plug for that end of the crankcase.

Instead of using the original screws to hold the crankcase halves together, I made up studs. The aluminum mounting stand offs are tapped, and screw onto those studs, thus holding the crankcase halves together. The standoffs are also machined to be a snug fit into the counter bores of the crankcase half, thus increasing their security even more. Extensive test bench running showed the mounting system to be stable and problem free.

It weighs 4 lbs. 8 ounces complete as shown, and handles very nicely. No porting was necessary as I checked the port timings and found them to be quite adequate. So, it is a bit lighter than a Zenoah G-62 Lite, and makes more power too. But it wasn't a "slam dunk easy" conversion.....

AV8TOR"

Note: Engine runs backwards from original rotation using a Hall Effect triggered CDI ignition. The cylinder is turned 180 degrees on whats left of the original crankcase. Otherwise the engine is stock including a Walbro HD18A carb. This gentleman lives in Mexico but is originally from Lukeville, AZ

Adapter for intake









The copper fittings on the muffler are for smoke fluid

7400 rpm with a Xoar 22 X 8 prop would be pretty much normal for a 62 cc engine as the ones made from the Dolmar's do about the same.

The Zenoah G62 (Red Max 625) does about the same though most people run a 22 X 10 prop and the rpm is around 7000.

The plane he put the engine in is a Wild Hare Extra 300 28%. It is somewhat pre-built and you have to assemble it and install your engine and radio. The plane is made in China.

Here is a build article but I'm not so sure you can see the pictures without belonging to the site?
http://www.rcgroups.com/forums/showthread.php?t=585157

Here is the assembly manual in a pdf
www.wildharerc.com/downloads/documents/Extra300manual.pdf

Here is a guy playing around with one in the air
http://www.youtube.com/watch?v=tEIsrsgyAK0

Here is another guy of one taking off
http://www.youtube.com/watch?v=e11syOmJPDI&feature=related

They generally fly around in the 50 - 60 mph range.

Some people still build the kits and cover them with silkspan, tissue, silk, or Dacron using the Nitrate or butyrate dope paints. You can get all this stuff from Sig Manufacturing Co. in IA just like back 50 years ago...

Anymore some people use Tyvec and water base clear Polycrylic paint or even the Elmer's type glues thinned down with water as paint.

Most people use a heat shrink vinyl covering know as Ultracoat or Monkote.

Some cover them with light weight fiber glass cloth (3/4 oz / yd) and epoxy.

Latex house paint works pretty good on the gasoline engine models