I've spotted an oil leak on the right hand side of the engine just below the front valve cover. it seems to be coming out of a hole that appears to be cast into the block.

What's going on?

I may be wrong but it Looks like were you plug a carb tune into should have a small screw and washer to plug it
least I think that's what it's for

water drain hole for the spark plug.
remove the plug and cap, and check oil isnt passing the plug sealing washer. if not then its just residue after washing the bike i bet.

Awesome. that explains it then.

i have got an issue with the plug sealing washer on that cylinder (when i put the spark plug in i can feel that the seal is not seated right as it is protruding into the hole wher you drop the plug in.

I was going to whip the rocker cover off and replace the rocker gasket so hopefully doing this will solve both issues.

cheers lads.

just need so sort out why the bike feels like its 'missing' at low revs now- Was thinking it could have been this oil getting into the chamber but when i took the plugs out the oil hadn't got past the plug thread so can't be it.