Runner 2T head cover spark plug seal leaking!

Hi. Just put a thermostat in my runner 125fx, last owner must have removed, it never warmed up as it was! I've put the head cover back on 3 times now and cannot get the spark plug seal to do its job, I've tightened the bolts as much as I feel is safe, tried new seals and the old one but nothing stops it leaking!! Any advice please??
Thanks,
Rob

 

Replace skull cap for a new one and new seal.

 

Guess you mean the head cover? Odd thing is it didn't leak before removal and it doesn't leak if I do the bolts up loosely, only when tightened.

 

Then in that case if it was mine, I'd open the 4 bolt holes a little bigger 1/2 mm should do, don't over tighten bolts as they are shouldered! The "gold coloured " center plug head I once used had this problem , drilled holes out, sorted it.

 

Hmm, interesting, I guess the assumption is that something is warped slightly and the more it's tightened the more it goes out of line.

Sorry to say I've bodged it for the time being, used some instant gasket on the spark plug hole in the head cover. Seems to be holding water now. Typically, one of the water hoses split due to all of the installation and removal, no longer available from Gilera/Piaggio so the I've cut the end off and reinstalled. Still long enough not to interfere with flow due to stretching/kinking.

I'll do a proper job on it if I ever get around to a complete overhaul.