Howdy guys.
I accuired a weedwacker .It's an old engine but it's not worn out. It's 28 cc .So i rebuilt carburetor and fired it up.Tuned it just right.Lowered rpm to the desirable idle..Boy i noticed this weedeater shakes so much.I have a plans for this motor to fly but if it will vibrate THAT bad in the plane i will leave it as a wacker. Did anyone of you converted 28 cc McCuloch weedeater?
What's your thoughs?

mitty: Try running it on glow fuel with a glow a plug adpter. Do not idle any slower than say 1100 RPM. See if it is smooth there. I have a G38 that will tick over on a idle....but too slow of a RPM brings out the shakes in any single. All you have to do is idle it slow enough, so airplane will not creep forward too mutch. I hope you get the idea. I have heard the glow/gas mix makes them run like a different engine. Good luck Capt,n

I recently converted a Mac 28 and do not see any unusual vibration. I assume you have balanced the prop and the flywheel? You didn't say what the "desired idle" was. Could be too low?

I can't help but ask: Have you taken it out of the weedeater yet?......Bob

No Bob.It's still in a weedeater.Thats why i was asking if others experience vibrations or not because if vibrating in it's nature then i will leave it in a weedeater.It runs great...But if motors overall are alright then i'll cut it out and will convert it. The more i run it the more i like it..I might just convert it ... [8D]

My 25cc McCuloch engines are reasonably smooth throughout the RPM range. Could be that something is bent and out of balance on the weed eater. Could be something simple like string on only one side.

Simply making an airplane engine from the weed eater will not fix the vibration. If it is rough in the weed eater it will be rough in the airplane. It is probably best to do the trouble shooting in current configuration.

Bill

Bills: I have rather strange news today. One of my Mb290 Mac engines throttle shaft just up and broke. To shut it down I had to choke it. After it shut down I noticed the control lever would turn 360 ...so I pulled on it very easy...it was no longer attached. I called the toll free no. They told me where to get service on it. I took it there and the guy called the same toll free no and found out this. If the repair cost 75% ow what I paid...I was to take it back and exchange it for a new one or another brand. Also ther are very few parts you can get...in other words...if they do not have parts....you only choice is to take it back where you bought it. Very strange. We will see what happens. Capt,n[:-]

Bummer Capt’n. A hanger crash. Hope Home Depot has at least one blower left.

Maybe a slightly bigger carb will be needed to fix the shaft. I think the shaft is a simple 3/16 brass rod with a half flat. Maybe flipflop still has the one he removed.

Bill

Bills: The easy parts ....external ones... don,t bother me too much. Its the parts you cannot find replacement for inside the engine that concerns me. The 1 st engine still runs perfect. Lots of use on it too. How you doing with yours? Smooth Landings Capt,n

what internal parts are you planning on failing? there's a whole 3 likely suspects, piston rod and jug, and for the price of those it would probably be worth getting another engine and keeping it around (especially if you can find one used on craigslist or something) and swap all onto the working lower end that you converted...