well, if you want to clean the engine inside out! take it apart ( there is a certain way to do it) clean up the internals/ inspect for damaged parts, re-oil the internals with castor oil which is found in mother nature supermarket etc... put the engine back together carefully! re-seal parts needed to be sealed and your good to go! theres no need of re-breaking in the engine b/c it is already broken in , for me i run the engine rich a couple of runs then tune it up again! this is what i do! taking an engine apart isnt going to do anything bad! this is what you do to maintain your engine after a long long long usage! dont do this all the time , but as your question it doesnt harm the engine unless you mess it up!