Matt@TYGA wrote:
[...] The insulator doesn't normally use a gasket as there's a seal built into it, but closer inspection showed that the seal was actually below the clamping face so was basically useless.
I checked whether the seal on my insulator is also below the clamping face and yes, it was identical to Matt's (Arrows point at seal's lip):
On the other hand this seal must have worked in the past because one can clearly see an "imprint" on the reed cages:
Maybe the rubber on the insulator shrinks over time and creates leaks on ALL of our NSRs irrespective of how well they were assembled? (correct torque etc.)
Opposed to Matt I think the main issue is the seal that no longer seals. The insulator, the reed cages and the crank case mating surface are pretty solid and I cannot believe that if the bolts are tightened to 12 Nm, anything would warp irreversibly. But that is just my opinion.
Btw, other than suggested in the thread, there is NO tightening sequence in the manual; but just like with multi-cylinder cylinder heads I would start on the four inner bolts and tighten the bolts in a cross pattern.
I will probably follow Matt's advice and use some Three Bond 1107B (same as for crank case) to seal it once and forever (replacing isn't an option because it is no longer available).