Agility Cylinder head removal

[Emil]

Hi,

My scoot (2009 Agility 125)  is having low compression and the issue points to the valves.
The scooter still runs fine, but is missing the 'oomph' that it used to have.
Unfortunately it seems impossible to just buy valve stems and seals, so I want to try my luck with doing some valve grinding.

Aside from welcoming general input I am having the issue that I cannot seem to remove that screw on the cam chain tensioner. It is now resting, soaked in pb blast, but in case that doesn't help - do I even need to touch that thing in order to remove the camshaft etc?

For the valve grinding I was planning to do something like this guy here: but without gluing anything to the valves.

Thanks,
E.

[Emil]

Ok, so I did get that cover screw off but now I am wondering what to do next.
The manual says that I should tighten the tensioner screw, but there's this outer ring with grooves and a screw beneath.
Does anyone know which one I need to turn? See attached photos from manual and scooter.

Thanks,
E.

[JJJoseph]

I can't make heads nor tails from your photos, but you can't remove the cam until the tensioner has been REMOVED, and the chain becomes slack.  Check the manual again, and look for a YouTube video on topic.

[Emil]

The maual says 'turn the cam chain tensioner screw clockwise to tighten it'
Sounds weird, I know.
The image shows what it looks like from the top: An upper ring with grooves and a seal around it and a regular screw beneath it.
Well, I will try my luck again one of these days.

[JJJoseph]

Be careful "trying your luck"!  It's easy to screw up this device, and it's hard to find a reasonable replacement, so do be careful and get expert advice (or a good YouTube video). On my Kymco, you have to remove the plastic engine shroud before you can properly remove the cam chain tensioner without wrecking it.