I did a little digging around and found that you should have a Kohler K582 and I already had the manual uploaded so here's the link.I don't have a diagram but if you tell us what kind of problems your having maybe we can help. The 520 has a simple electrical system since it doesn't have the BICS. Also I have the service manuals for most Kohler engines if you tell me what the model number is I can post a link for you to download it.
Not able to download from Media fire.I did a little digging around and found that you should have a Kohler K582 and I already had the manual uploaded so here's the link.
http://www.mediafire.com/file/gnjmirmdzwn/Kohler_K_twin_cly_service.pdf
Go here and scroll down near the bottom to K582 and you can download it direct from Kohler.Not able to download from Media fire.