Confused
 

I want to convert a 25cc homelite weedwacker engine to a plane engine and I have been sitting here reading post after post and after all the reading there is one thing I know and that is I am confused.

I purchased a reconditioned weedwacker from a traveling tool equipment show in the summer. Supposedly it is a 25 cc engine but the exhaust port is not bridged so is it a 25 or a 30? The displacement is really not why I am confused. The confusion points are this.

So I take this engine (which is sitting on the table next to me) and I carve it down. Now I am left with a cut down engine and what is next is what I am asking my self.

The engine is reconditioned. Does that mean I need to install a Bowman ring?
It came with a 9mm Zama I guess that means I need to go to a 11 mm Walbro
Do I go with CDI or stay with the mag ignition?
Twister manifold seems to be a must as does a new muffler?
If I do not go with a CDI I need to have the flywheel fins cut off and the flywheel rebalanced?
If I stay a mag ingition I am looking at a boat anchor of an engine
Do I need to remove the base gasket and adjust the port timing?
Do I need to cut down the squish?
Is a 35mm (protruding from the front bearing) a long or short shaft?

The plane I want to put it on is a Birdi Big stick or an Old Timer. These are 9 lb planes with 80" wing spans which should support the square inch to weight recommendation.

I would really appreciate some guidance with this project.

Thank you.

RE: Confused
 

I happen to of just finnished my Old Timer and they take a lot of weight up front to balance right.
I did put a Quadra 35 on mine with the starter spring and flywheel and I onlu added 4 ounces I think to the tail.
The 25 is going to be real light for this airframe so I would leave the flywheel on, because weight will not be an issue.

You probally only have one needle on the carb. so if you hollow out the muffler, or put on an after market one you will need to upgrade to a 2 needle setup. The twister manifold only is needed if the needles are to close to the prop to adjust safetly.

There is a lot of stuff you can do for that extra 500 or if your lucky 1000rpm.
But there is a lot to be said for flying it as is.

I'd get it setup and fly it first. If you need more then there are things thak can be done.
But if you fly at 3/4 throttle or less it won't make much of a difference.

Check these guys out, you should have a lot in common. http://wackerengines.com/

By the way I'd get the 1.5 inch engine mount. You are going to need the weight far forward to balance the Old Timer.

My Old Timer is done up like the picture by my name, well almost.

RE: Confused
 

Hey, you probably have a 30cc. Most of the late Homeys were. Even the Ryobis with the yellow boom were Homeys. I have just finished one of these. It has been redesigned with a new cylinder. I was skeptical if it would match the old Homey as maybe it was an emmisions engine, but it runs fine. Mine is on a 16lb H-9 Super Cub and it flys it with reasonable authority. You should be fine. Do like Ralph says and dump the carb.

RE: Confused
 

By the way this engine will hand start, (with the stock mag) where as the older Homeys require an electric starter

RE: Confused
 

Most of the concept with rotating the carb on a manifold is to have a straight shot for the throttle pushrod. You can make your own if needed. I just made a new one for my 31cc Honda so the carb lines straight up. You can read till your eyes burn but for the most part run what you have. Everyone has their favorite engine or tricks, I like Echo's for my planes but I have done others. The idea here is to fly gas for sure but also to do it cheaper than buying a new engine. Find a combination you like and apply it to every plane or engine you do. When you go to bigger size and higher performance planes you will find a larger window of engine possibilities. I have 2 large concrete saws to do, a Partner and a Target. Ralphbf has a Partner saw and will be done before me so maybe he can say how it is going. FWIW if you have access to a mill and or a lathe you can do anything you want with these engines. Cheap too.

RE: Confused
 

In spite of all the info (good and bad) that's out there, this ain't rocket science. Check out Carr Precision [link]http://home.att.net/~carrprecision/[/link] for conversion parts and accessories.

Don't put $200 worth of upgrades on a $50 engine. Most of these engines will fly our planes just fine with the basic conversion parts. If you need a hot-shot engine, then buy a hot-shot engine.

Dr.1

RE: Confused
 

Thanks for the input. I was beginning to wonder about this process. Start with a 50 dollar engine then add in a EI, and conversion kit and Bowman ring and.... It does not take long too break the 300 dollar mark. For that much I can purchase a "regular" 25/26cc engine.

I am going to do the normal stuff (mounts and muffler and such) and see how it works.

RE: Confused
 

Perfect.

Get it going, then see what it needs.