How do i change the cylinder head

[Beddy]

The threads where the spark plug fixed into the cylinder head have become damaged. The spark plug is now screwed in, but cross threaded. That said it appears to be in fairly tight.
Firstly does anyone know if this will affect the performance of the scooter?
The scooter appears to run fine, at top speed but struggles as the revs are building? Could the dodgy spark plug fixing be the cause?
If so can anyone tell me how to change the cylinder head? Does the entire engine have to be removed? Ive tried searching the forum but the search facility doesn't appear to work.
Many thanks.

[Gid]

i wouldn't say u have to remove the whole engine but strip down the cowling so u can see the engine and acces it, simply remove and plug/pinch cooling pipes and watever else is there and remove the old one and put the new one on, then tighten it up, put everything back on and away u zoom !

[williamr]

i wouldn't say u have to remove the whole engine but strip down the cowling so u can see the engine and acces it, simply remove and plug/pinch cooling pipes and watever else is there and remove the old one and put the new one on, then tighten it up, put everything back on and away u zoom !

No need to replace the head for this. It's a common problem and the standard repair is a helicoil insert. Best done with the head removed, but it can be done in situ as long as care is taken. If you don't have a bike dealer handy, most car mechanics should be able to fit a helicoil.

Rob

[Beddy]

I did have some work done on the scooter by a dealer. They told me, for some reason, that they couldn't Hellicoil it. Not sure why?
Any comments about the affect on performance?

[williamr]

. Not sure why?
Any comments about the affect on performance?

Not without seeing it.

If the plugs down on its seat I can't see it having anyreal effect.

Rob