Reply To: No spark gt125r 06
1 brown valve in he picture looks like it has been through some hell judging by the edges of it.
A valve head change or valves alone + seals could be a safe call to change up. The valves are very hard to press down with your fingers , so amazon a cheap tool that allows you to compress or extract valves so you can see the full state of them and the seals (compression loss? or tiny bit of oil burning possible)
Pistons & The Cylinders, you would end up needing to remove the pistons and the cylinder walls now to judge their condition with your eyes
, if they all look good, grab a spare piston and use its rings to see if compression improves.
Remove the piston slowly! = So you can see which position each ring was, they have a notch on them and mark them. So next time you fit a piston, you can remember how they were.
Like this one:
