No, a full rebuild isn’t cost effective. A full rebuild would consist of the con rod, all bearings and bushings (where applicable), piston and sleeve, gaskets, O rings (where applicable), head buttons etc...

You have to keep in mind the #1 failure in an R/C engine is the piston/sleeve. In time, it all wears out but the piston/sleeve usually wears first. More often than not, by replacing just the piston and sleeve, you get many more hours, days, months and sometimes years out of the same engines “bottom end”. That’s cost effectiveness that works.

Prices of parts differ from manufacturer to manufacturer. That’s just the way it is.

At times, with some engines and manufacturing pricing, it’s just as cost effective to replace the whole kit and caboodle.

If a piston/sleeve kit is cheap enough and I have an engine “going bad”, I’ll pick up the kit and a new engine. Nothing beats a spare aye?

Example: (the numbers aren’t accurate, just an example)

Lets just say an OS .15 piston/sleeve kit sells for $40 but a new OS .15 engine sells for $120. I purchase both. Why? Now I have two good working engines for $160.

See the benefit yet?