ringed engines start off with less compression then get better.my new magnum .91 4 banger has the most compression i have ever felt
adjusted the valves on it and wow talk about compression.i was sure it was hitting the valve or something but it wasnt.
im not sure if ill be able to start it with my dinky starter and old lead acid battery.

check the compression when its cold. it should feel the same as when you first got it, or a little less.
check to make sure you arnt to lean. if you are not then i would keep running it.
i have a old magnum .40 that has some,but not a lot (compared toa semi-newgms .47) ofcompression. but it runs really well. not very powerful by design (bushing engine)but it wont quit in the air and could care less what plug/fuel i ran through it.
the only problem is it spits out loads and loads of castor. my gms.47 and .32do leave oil on the wing, but this engine just covers everthing in oil (the plane is aspad so i could care less)