I've always been able to get my jugs clean by liberally spraying them with whatever flavor of ammonia free Windex Renea has laying around, brushing the fins with a soft bristle brush, and then I use copious amounts of rinse water under low pressure. After drying it off, I'll run it until the engine, primary, and transmission get warm........not hot. After shut down, I'll spray the whole engine, primary, transmission powdercoat area with armor all and let it sit for about an hour. Then I wash the bike as normal. First, It really blings up the powdercoat and brings out the new looking silver we all saw in the showroom, and second, it makes future bug removal easier. Always works for me. Same procedure I've always used even with my black powdercoat engines.