Clean out wells
Drain oil tank and wash out with petrol
Fill with Castor R40 Castrol R 40 is what I use
Pilgrim works better
Thicker oil film on bores stays after engine stops for better hot start sealing. Engine lasts longer and is more smooth.
And it smalls great.
If you leave the bike stored for more than a month, take off doors and mop all oil from wells before starting
If you get stuck for supplies on long journey, go into Boots and buy a big bottle of their pharmacutical grade castor oil. Elf used to make an R40 Castor racing oil called White Ideal Racing. They bought it from Boots!
Try it! If it works for you, write your experiences for us.