Reply To: New problem and I can’t figure it out – Hyosung GV250
Could be pistons/piston rings or valve seats themselves as long as you are certain the valves are 100% straight.
Put a new metal gasket again just incase. (Compression loss due to head-gasket failure can happen , just like cars)
The site’s image uploader seems to have bugs i am sorting soon, so in the interim, use this website to upload images below:
https://postimg.cc
Then just copy & paste forum links that start with "[ I M G ...........]" , this forum will translate them in to live images.
Sorry for the hopping around , I will fix the site’s uploader.