Hi Frederic
regarding your annoying ticking sound:
--probably just the valve clearance too big.
piston slap is not ticking but more hammering sound
ring noice.
--???
But the real reason (and the one my wallet hoped for) was that the
fuelvalves which are vacuum controlled where ticking.
--you wouldn't hear that
I also had a little leakage on the intake side.
--normal
The reason for the tick may also be worm O-rings in the valves
that lets metal hit metal.
--No
these o-rings do not impede the valve touching its seat!! if so your valve would burn!
I Have two advices
1. try adjusting the valve clearance:https://www.tr1.de/tr1/tech_info/page2e.htm
2. wear a soundproof helmet
cheers,
Klaus
vous êtes par chance francais?

Hi Frederic!
funny thing that ticking!
i just had a similar problem but it was clearly the front cylinder Valves
after adjustment the noise is gone..
I couldn't image that you might hear sth as small as a fuel valve ticking
in all that racket!!!
anyways..
give me a mail once you pass Karlsruhe on your way down south
cheers,
Klaus