My question about lubricating automotive gears and chains also got me thinking about cleaning said contrivances which is required prior to lubrication. Oftly, kerosene is used as a generic cleaner. Other chemicals harmful to the environment could also be used.
I know there are biodegradable cleaners available, such as some citrus-based solvent I have to clean bicycle parts, but those come in small and expensive containers, and I could easily use a quarter- to a half-litre of fluid to clean, say, motorcycle chain, depending on the degree of contamination. And it could prove really spendy in the long run.
Is there generic category of biodegradable solvents that can be purchased cheaply and/or in bulk, and at the same time provide decent cleaning performance?