Engine running in

[madmog]

How many km does a rebuilt or new ETZ 250 take for the engine to run in (loosen up) please?

[hiha]

That depends on how you pratice running in. And of course, whom you ask
I would say, piston rings are the only thing to run in, and that's the case after 250-400km.
Don't use more oil than 1:50, let the engine spin, but only short time with high load. Have a look that carb setting is more on the rich side, than on the lean.
Cheers,
Hans

[madmog]

Thanks