1977 Polaris Air In 1977 Honda Express NC50 Oil Lines, Any Ideas Why? And How To Remove Them?

Air in 1977 Honda Express NC50 oil lines, any ideas why? And how to remove them? - 1977 polaris

I recently put the oil (synthetic Polaris 2-stroke) and I noticed air bubbles in the oil pipelines. Follow the instructions on how to bleed the oil pump, but I'm still in the air lines! I have tried everything to get (and keep) out.