Thinking of doing mine too as large sections are now peeling.. I intent to rub down with wet and dry first.. but paint on or spray?.
Ta
To make a decent job, you're probably going to have to remove your heads and barrels - it'll be just about impossible to manoeuvre round them and paint them in situ (assuming you're spraying). Obviously this makes it a bit more of a job....
Regarding brush or spray - Most people (me included) choose to spray. It can be very difficult to get a decent finish when brushing (not so much of a problem on your garden gates but it matters a bit more on your bike). However it can be tricky to get an even coverage between the fins unless you attack it from just the right angle (another reason to remove the part from the bike). I did my front engine cover and rocker covers and even the shallow finning in them was tricky - I don't know how you'd get decent coverage on the much deeper barrel finning without getting too much build and runs on the fin edges (I think they're powder coated in the factory?).
<a href="https://picasaweb.google.com/lh/photo/hbrgsqboHln1wP5PgfCaOBJAieIP4IByCYmMpeOVcwI?feat=embedwebsite"><img src="https://lh6.googleusercontent.com/_SSn2CtCOKnU/TG_4IdIdJJI/AAAAAAAADps/OyojCM2BOI8/s800/IMG_5641.JPG" height="600" width="800" /></a>
Where the existing coating is sound, it's rock hard and stuck very well indeed. To strip the old coating I used home made brass scrapers and home made dremmel tools to get between the fins to remove flaking coating and feather the edges of sound coating (obviously easier with the shallow finning on the rocker covers). It was a long winded faffy job though...
<a href="https://picasaweb.google.com/lh/photo/ATpB4VsUwzLIdLBwoblURhJAieIP4IByCYmMpeOVcwI?feat=embedwebsite"><img src="https://lh4.googleusercontent.com/_SSn2CtCOKnU/TG_4jA_I3YI/AAAAAAAADqA/xZHBNWoFhcQ/s800/IMG_5635.JPG" height="600" width="800" /></a>
A final thing is that I'm not sure how well Hammerite will cope with the heat of the barrels. I'd imagine you might get some yellowing but perhaps not enough to worry about.
