Some engine work, latest project

[BillH]

Well, that thread on the Merlin engine was amazing, but if you want to do some engine work thats quick and a lot of fun, this is what I've been doing.
This was a stock run of the mill 25cc Homelite weedwhacker engine that I am modifying to be water cooled and used on one of my R/C boats. I've been told by nearly everyone that my 40" long R/C boat was too small to be gas powered. Well, I never bought into it.


As you can see, I cut off the huge fan shroud around the block, leaving the bracket for the magneto, I milled back the lower part of the block so I could drill and tap for 2 engine mounts in front, and I turned down the cooling fins on the cylinder on my South Bend 9c. The mill I used is my tiny harbour freight micro mill and it did the job. Next couple of things I need to do is turn off the cooling fins on the flywheel, remove the starter prongs, and rebalance the wheel, and to make a water jacket for the cylinder. Naturally I would of loved to keep the pull starter, but its too much bulk for my boat, and when I originally aquired this engine, I had it in mind for an Aircraft engine, so I threw out all that stuff. Really dumb, considering how drastically my mind changes all the time.
I also have a Ryobi 4 stroke 26cc weedwhacker engine Im going to save for a future project. These engines are a lot of fun to work on and are dirt cheap.

[This message has been edited by BillH (edited 05-18-2004).]

[This message has been edited by BillH (edited 05-18-2004).]

[This message has been edited by BillH (edited 05-18-2004).]

[G.A. Ewen]

Neat idea Bill! Please keep us updated on this project.

[winchman]

Just curious.

The crankcase appears to have four holes for mounting the cylinder. The cylinder has two mounting holes, which are not on the corners. It looks like the cylinder will be mounted with the exhaust port at a 45* angle to the crankshaft, which is very unusual for this size/type engine.

It doesn't look like a Ryobi cylinder, which has two mounting holes (one on either side) with the exhaust out the back.

Are there some other holes we cannot see in the crankcase for mounting the cylinder? It almost looks like the cylinder doesn't go with the crankcase.

Roger

[This message has been edited by winchman (edited 05-19-2004).]

[BillH]

The cylinder has 3 mounting holes, 2 on one side, 1 on the other. It is not a ryobi, but a Homelite engine.

[This message has been edited by BillH (edited 05-18-2004).]

[Paul Gauthier]

If you have no pull start, how will you start it????
I expect it will go really fast. Very interested to see end result.

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Paul G.

[BillH]

What Im doing has been done by countless other people for R/C boats and model airplanes. Well, I figured I would put a smaller pulley on crankshaft and crank it over with my electric starter I use for my airplanes. Same way glo powered boats are started.

[gizmo2]

I think what I love most about the fractional hp motors is the response when you make a change. I'm running my bicycle on a 31cc four stroke weedeater motor, and a little tweaking can make some major changes in performance. If you add 10 hp to your 200 hp car, how often do you get to enjoy the fruits of your labor? Add .1hp to your weedwhacker powered gizmo YEEHAW! it screams. Cheap thrills, and you're in it every time you fire her up.