I recently converted a weedeater engine. I wasn't happy with the backplate I cut from the housing, so I machined a backplate from black nylon.

Jeff

Sounds pretty cool, any pics??

I was considering cutting one from aluminum, but then I found the original that I had put somewhere safe

I had good luck rough sawing most of the excess then grinding/sanding to final size, but I've been practicing. Next step is to chuck up the crank case and turn down the front nose to minimum thickness.

I'm having problems trying to upload an image, will try again

Jeff

IIRC, you have to sign up with a photo hosting site like photo bucket, then you can post a link to the photo bucket image. It's a little bit painful to set up, but the next picture is a cake walk.

jp1961,click on ,Reply to Thread,then the Go Advanced button.Go down to Manage Attachments.In the box that comes up click on Add Files at the top right of Upload Manager,then click on Select Files at the bottom of the box. Pick you pics from your computer and click Upload Files.After you see the pic in the long box at the bottom of the Upload Manager,click on Done and you pic will be posted in the reply.I posted a pic of one of my converted engines to show what it looks like when your done posting your pic.

Nice looking conversion, powder coat on the crankcase?

I just started powder coating a couple of weeks ago, works pretty good. Have to finish soda blasting my latest conversion so I can se how it works on engines.

No,the green is 500 deg engine paint with 500 deg primer under it. The cylinder is 1200 deg paint.

hopefully this picture uploads

Jeff,

Nicely done! (both the back plate, and posting a photo) That looks like it was done in a pro shop. How big of a chunk of black nylon did that take? Did you do it manually or on a CNC machine?

I don't know about anyone else, but I think I enjoy the build more than flying. I was out cutting down a crankcase on the mill this morning, heading back out with the camera to get some picks.
Al

Thanks (for both the positive comment and help with the image upload). *I machined it from a round piece of black nylon rod 4" in diameter on my lathe (Emco Super 11), then cut the flat areas with a manual Bridgeport. Then recessed the back to save weight. *The nylon does seem to absorb some of the vibrations.*

Did you stuff the crankcase to decrease the crankcase volume or use original spacing from the inside of the backplate to the crank? I don't go any lower than.015" and to a max of .020" Also I know of an r/c boat engine modder and converter that cuts out for the port to give better flow.He does this by filling the area on the back of the backplate,where the cut would be with JB Weld and then cutting it out in the right area.I haven't tried this yet on an aluminum stamped or plastic backplate.I had a cast aluminum backplate on the engine above that had this done from where it was made.I don't know what it was made for ,but it fit the 30cc Homelite and gave me a space of about .018.Also adding an 11 mm venturi carb will wake it up .Ask my 21cc Weedeater Featherlite trimmer.Here's a pic of the backplate.

The backplate has a plug, with the same dimensions as the original. *I machined a slot similar to the original. *I'm assuming that wedge taken out of the backplate allows fuel/oil to lubricate the rod (not 100% sure).

Jeff

I cut down the front end of a Homie 25cc crankcase (I think it was a 25cc Homie, it's been in the engine drawer for awhile)

Take care when cutting the magnesium cases as it is easy to start a fire if you get a little carried away on speeds and feeds.



First pic is the original Homie case with cut down flywheel and prop mount.

Second pic is the Homie jug after turning fins with a 21cc Weedie stock crankcase and flywheel for comparison.

Still needs cleanup and powder coat.

The stock 25cc Homelites have a bridge in the exhaust port and the 30cc doesn't.I have a 25cc that was modded and the bridge was cut out by the modder.