Picked up this engine at a swap meet from a guy selling it for a friend. Most of the hard work (machining of new hub etc), has
already been done so it seems like a good candidate for conversion to rc. Problem is, all the identifying marks/labels have been
removed so I'm not sure which echo engine it is. The guy just told me it's an echo engine in the 20cc + class, 21-26cc. If anyone
recognizes this engine, please let me know which one it is so I can figure out what spark plug to use and which electronic ignition
to get for it. Going through these threads it sounds like echo's work pretty well for conversions so I'm going to give it a try. The
carb venturi seems really small so I'll probably have to go to a larger one, maybe 9mm. This is my first attempt at doing this so
any advice would also be appreaciated. Thanks!
Jim

it should just take a standard spark plug with 14mm threads, shouldn't matter whether it has a tapered plug or a plug with a seal washer, just get the ignition you can find for a good price...

I don't recognize the engine right off, I don't think it's one of the 16cc engines so it's most likely a 21.6, 23.X or 25.X, to find out if no one else chimes in, if you have a digital caliper measure the bore through the exhaust port and the stroke through the spark plug hole, to get the size use this formula:

3.14*bore*bore*stroke/4

if you measure in inches you will get cubic inches, if you measure in millimeters divide by 1000 to get cc

I'm thinking it's a 21cc echo.

Somewhere there is a hop-up for this engine.
I had the link on my old hard drive.

Perhaps av8tor could chime in on this one.

Guess I'll measure it and see what I come up with. Didn't realize Echo made so many engines in that displacement class!
Thanks for the info! Jim