The formula of berrymens says plastic and rubber is Ok ??? But I remember having issues with both . Berryman Carb Cleaner
Berryman® Chem-Dip® Carburetor and Parts Cleaner
Fast-acting immersion cleaner for all metal parts, including alloys. Removes gum, varnish, sludge, carbon, and grease without heat or agitation. Non-chlorinated and nonflammable formula is VOC-compliant in all states. Safe on plastic and rubber and will not cause rusting. Use for cleaning carburetor and transmission components, valves, and other small, hard-to-clean engine parts.