That is the cam chain tensioner. Don’t remove the large nut. If you do, you will need to complete a procedure that I’m guessing you won’t know how to and can make a mess. The smaller nut is ok to remove and check the baby oring that helps seal it.

 

That's your cam chain tensioner. Have a look at your service manual for part number and location of o ring and its seal. Check them to ensure it isn't loose. Do not remove anything without following service manual procedure exactly. You can cause engine damage.

 

Okay thank you, the bike has a dirt tricks cam chain tensioner in it would that make a difference in being able to remove the big nut?

 

If it had a stock cam chain tensioner i would say you need to remove the valve cover, lock the crank, then set the hyd plunger correctly. I’m not sure with the manual tensioner.
check online and see what they say

 

If it had a stock cam chain tensioner i would say you need to remove the valve cover, lock the crank, then set the hyd plunger correctly. I’m not sure with the manual tensioner.
check online and see what they say

Additionally, I’m a KTM tech and have never seen a leak from that area. Did you tighten the big nut against the copper crush? And check the baby o-ring on the small bolt?