throw in some 100LL Avgas. even 20% makes a difference. 100 "low lead" has about 4x the lead that the old leaded 87 octane had. its $5.50 a gallon where I am but it works. old bikes love leaded gas
and yeah, those additives are a joke
I run Avgas in all my machines. Cleanest plugs ever. No deposits. Avgas here right now in this valley is $4.25 to $4.95 self service. Avgas has a long shelf life and doesn't stink bad like pump gas.