Hello all, Run in is very improtant and i think it realy depends on the engine brand as to how you should run the engine in Most of my exprence is with Sirio engines and There is only one way to run a sirio engine in properly and thats full throttal at a supper ritch carb setting and useing the fuel tank lid to keep the engine running. But I think there is a defrent methed for A novarossi based engine thats novarossi rb concepts novabase engines and maxpower shark ppx I find they like the idle heat cycle methed. It realy should only take about 40min of running for an engine to be fully broken in. A Properly run-in engine you should be able to remove the glow plug and the piston should turn very ezy and not lock or grab. But when the plug is in the engine has a tone of compreshion. An engine like that is ready to rev very high and hard. But Apart form that I think it realy depends on the type of engine you would not run a force engine in like a sirio. Thats my thoughts It is a very tricky subject to comment on as so many difrent way can be used and Probaly all of them work if done properly. Regards Jeremy.