Pictures will help, they are worth at least a 1,000 words and can save a lot of confusion and misdiagnosis.
You can just drag and drop them into your post.

 

Thanks. I will take off radiator tomorrow and get dome good pics to post. I do realise that it can be very misdirecting and misinterpreted.

 

Can you clean it out with brake cleaner and a Q tip and see if it has threads?
Or if not maybe it is an oil passage drilling that a plug fell out of- ???
But 1 MM is pretty small.

 

Here are some pics off the leak

 

To me that looks like a valve cover gasket leak on the left side of the engine that is working its way across the front of the engine through the gaps and fins and the exhaust port is just one place it has ended up. It looks as if it has been leaking for a while judging by the build up on the cylinder fins at the front, that flow probably occurred while on the side stand and now you have it upright and in use it is making its way to the exhaust port area.

Clean it all up with solvent and a brush, wash it off so you are looking at a clean surface and can see what you are actually looking at and can track any new leakage flow.
I'd replace that valve cover gasket or at least remove it inspect it, reseal and refit it to eliminate that source before going further.

I will now turn this over to @swifty2014 and he can explain about using baby power or talc to track oil leakage as he is better at detective work that than me.

 

I think we found it. Looks like oil leaking through the spark plug, and then drains at the hole.

 

Good. These are normally pretty much leak free engines so it is unusual to see one leaving oil tracks.
When it happens it is usually a gasket or a seal gone bad somewhere.

 

I wasnt sure. I know Yamahas dont have issues... But ther

Good. These are normally pretty much leak free engines so it is unusual to see one leaving oil tracks.
When it happens it is usually a gasket or a seal gone bad somewhere.

I know Yamahas dont have these issues... So was a bit unsure about this Honda ?

 

That hole appears to be a drain hole for a recessed area in the top of the head, purpose is to keep water from standing in the area. possibly one of the spark plug holes, so CS is most likely right about a valve cover gasket. Blow some brake cleaner in the hole, see where it comes out, may need to remove the spark plug boots.

I'd bet it's #7 on here: 1999 Honda VT600C A CYLINDER HEAD COVER | Ron Ayers

looks like the front head cover gasket has that extra bit to go around the left front plug hole.

 

Figures, I started typing that 2 hours ago, then got tied up on the phone... came back and hit enter...

might just need to re-tighten the valve cover bolts, see if it stops. And it IS 21 years old,,, gotta expect some issues.

 

I think you guys are on it. I remember there is a drain hole from my spark plug wells. But the 600 is different with a plug in the top,so maybe it is from a seep at the valve cover on that engine.