Hi,there is a product to clean the alloy of cylinder and head, or the only way is to blast?And with what material you blast?

Hello Mac (is that your name?)
Everybody has his own method, they all seem to work as long as you are patient.
I always clean an old cylinder first with paintremover (dirty job), then remove difficult dirt with a scraper. This you do only with streetbikes of course, racers never get so dirty. Afterwards I always beadblast (fine glass) the cylinders (also crankcases). When you use very fine glassbeads you get (anyway I do think so) a very good finish. Finally a small touch-up with fine steelwool does the rest!
With kind regards,
Ludy Beumer

I find using a wire wheel in a drill works on most things, using a strong solvent to dissolve the worst is the way to start & then soak in WD40 or similar & go at it with the wheel. I sometimes polish edges of fins/rocker boxes etc with Autosol & a cloth wheel too depending what bike/finish I'm after.

Generally it's what works best for you though.