Howzit - so bought my kid a 50cc - had very low compression - around 30psi - after removing the psiton I saw that the lower piston ring had an expansion ring behind it that had broke.... my question is what is the purpose of these rings - I installed new rings but still low compression .... I have now ordered the expansion rings to see if it helps ...

 

I assume they keep the rings pressed hard against the cylinder walls. Not many bikes have them, seems to be a 2 stroke thing, fairly sure standard Suzuki LT80 pistons have them but oversize LT80 pistons don't

 

ordered a new set and came with the compression ring - after installing it bike runs well - just over 90PSI