I could make this short ....go by the manufacturer of the paint .
O.K.Peter,painting i do no,well so can any-one ,Paint will not last unless prepared right.period.paint cannot stick(stay stuck to) raw metal without A chemical reaction to cause it to,etching,appropriate primer/sealers,"Heat" causes chemical reactions in some paints,most say no primer needed(wont last),i use V.H.T.500degree paint all over my bike's,(but engine),ever thing seems to close to heat is why.
barrels and head should always be pre heated in order to last,Many new products out there so others may no better,but let us no after the fact about your experience,My El Camino engine block just starting to peel been 5yrs since painted used it's own heat after running long time v.h.t.5,000 paint ?...Piute...
..also used v.h.t. primer in places.
1977 CB750 F2 Super Sport
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