well, i checked the reed valve and it looked fine to me. then i opened up the cylinder and the head had about 1/16th inch of really hard black buildup which hadn't previously been there.
in the end, i have a second spree which i can't license because it's tabs expired in the '90s, so i pulled the engine head, carb, and reed valve+manifold and stuck it on my scooter =p lol. i feel like i totally cheated, but everything looked fine to me, aside from the head!! i'm so confused. there's a chance it was the reed, but. whatever. my scooter works fine now

i went and bought new fuel lines too to fix a separate issue.
thanks for the suggestions guys
