First conversion - craftsman weedie
 

Hi all.

Been lurking for a while, finally got the conversion bug. I aquired 4 weed eaters of various types/brands to play with. My first test subject is a craftsman brushcutter model #358.797270. A lookup of the craftsman manufacturers code says it is a Poulan engine. It has a Phelon flywheel/ignition and a walbro carb (I'm not sure what model)

I haven't been able to determine what size the engine is, does anyone have a clue based on the sears model number?

I am working on a deal to aquire a mini-lathe so I can machine the fins off and make a prop adapter for it. I'm wondering what treatment to give the face of the prop mount? Do you just leave it smooth or use something to create ridges in it like what I find on my glow engines to help grip the prop?

I also got a McCulloch 18cc, Ryobi 31cc and a different model craftsman (poulan) 22cc. I haven't torn any of these others apart yet. I know the Ryobi is the only popular one in my collection, but I'm planning on doing my own machine work and then just see how much power/weight I get from each of these. I'm hoping to find a suitable engine for a Dynaflight 89" super decathlon out of this batch as my first gasoline powered aircraft.

Here is a pic of the engine after removing the weedeater parts and cutting the plastic carb mount out of the case:

http://www.rv10project.com/enginesmall.jpg

RE: First conversion - craftsman weedie
 

31cc for the decath for sure.good luck. i just got hooked and now have 6 engines ,one plane that has one, building a second.im still looking for more engines(duh).engines are hard to passs up when given to you.

RE: First conversion - craftsman weedie
 

I beleive your looking at a 22cc engine there. If this is your first conversion and since your looking for an engine for a 89" decathalon, I'd suggest you gut out the Ryobi 31
THere's plenty of ready made parts to either buy or copy and the 31 will make enough power for the plane your planning. If I'm right and that Poulan/sears is a 22cc I'm not sure that you'll be happy with the results

RE: First conversion - craftsman weedie
 

I agree, the sears engine is probably a 22cc. I'm not necessarily planning to fly it, but I've been using it as a test bed to see how to perform a conversion in general. My goal is to develop the skills required to convert them without purchasing ready made parts. So far, I have machined the flywheel, created a prop hub, a rudimentary engine mount, and mounted a prop to it. I'm going to bolt it to a test stand tonight and fire it up. Here is a pic of the progress so far:

http://www.rv10project.com/RCPhotos/Poulan22cc.jpg

RE: First conversion - craftsman weedie
 

Hi! Your engine looks good! I don't think that it's as small as 22cc. I believe those type engines built by Poulan came mostly as 26 or 32 cc versions. They are rugged and run well but suffer from a small carb and little ports. It will be interesting to see how it compares to the Ryobi's as they are very similar.....Bob

RE: First conversion - craftsman weedie
 

Yeah, I'm not sure about the size. If I tear it down, I'll measure the bore and stroke. I have two of the sears/poulan engines and one of them is a 22cc, it has a label on the trimmer head. I looked at the parts diagrams for both engines and they share the same case, but the crank, piston/rod, and cylinder are a different part number. It is from a 'brushcutter' so it probably is a bigger engine.

I got the thing mounted on the test stand last night and tried to fire it up. I discovered that my 12v starter that I use for my small glow engines isn't up to the task. Then I tried my 12v cordless drill and it isn't really up to it either. It spins it, but not fast enough. I put an AC 3/8" drill on it and that does the trick. I couldn't get the engine to run for more than a few seconds though. It was either getting too much air or not enough fuel. The spark looks good. I took the carb off and stopped by a repair shop for a carb kit for it. While examining the carb at the repair shop, I found that a piece of the old fuel line was stuck in the fuel nipple causing about 90% blockage. When I get home tonight I'll clean out the blockage and try it again. If that doesn't do it, I'll rebuild the carb and try again. I'll get some pics of it on the stand tonight (hopefully running).

RE: First conversion - craftsman weedie
 

Great! Looking forward to the pictures and a running report. If you need any extra pieces for that engine let me know. I have a pile of them......Bob

RE: First conversion - craftsman weedie
 

The engine you have is probably a 25cc or 32cc. I have both and they look the same. The 25cc has a larger bore carb than the 32cc. Take a look into the carb, if it's really small, then it's the 32cc model. My 25cc with a bored out carb would turn a 15X6 around 7400 rpm. The biggest problem is they are very heavy for the power they put out. The Ryobi is the better choice here.

RE: First conversion - craftsman weedie
 

I took the exhaust off and this is two-ring piston. I'm not sure it was broken in very well because I can see the original machining marks on the rings. The piston and cylinder walls look very clean, the bearings are tight, engine internals are in good shape.

I Got it running last night. I put a carb kit on it and fired it up. The carb on it is a fairly large bore so maybe it is the 25cc engine. I put a 16x6 prop on. It turns it at 6000 RPM, idle at about 1700. It has a bad reed so I'm going to put a new one on it to see if it improves. There is a lot of metal that could be trimmed off of this engine to save weight and a lighter engine mount could be utilized. Here are a couple of pics of the sears/poulan running:

http://www.rv10project.com/rcphotos/...nningSmall.jpg
http://www.rv10project.com/rcphotos/...FlashSmall.jpg

I haven't decided if I'll continue to play with this one or dive into one of the Ryobi's I've got sitting around next. The 31cc ryobi I have has a Zama carb on it. I think the other Ryobi is smaller and it's carb is trash (no low speed needle).