How do i go about putting a heatsinc on the rectifier just to ensure it runs cooler? any idea's or known ways? the one ive got on my bike isnt like the original one, its a bit bigger but doesnt have any finns?
The fins on the original rectifier don't do most of the cooling. Most of the cooling comes from the frame that the rectifier is mounted onto. Just make sure to put a thin film of heat transfer paste on the back flat side of the rectifier that gets mounted onto the frame. Also before adding the paste make sure the frame area and rectifier area that are mated is clean of any dirt and oil.
I found that the previous owner of my bike had put grease on this area and grease is not a very good conductor of heat. So I cleaned it off and put the (white) paste on the affected area's. This is the most important part towards keeping the rectifier cool!