Quick question, what's the easiest way to clean the engine block,  specifically in thr fins,  seems to be a yukky deposit building up, 

Go to your local pound shop. buy their pack of kitchen brushes then get yourself a tin of oven cleaner, go home, grab a bucket of hot water and your preferred soap, then have at it, don't leave the oven cleaner on to long (5mins) then rinse it off, run your motor till it's dry and job done, oh yeah tea & a biscuit helps as well!

Like slice said, oven cleaner works well for me when I give my bike it's bi-yearly wash