>When you torque the nuts, you will notice that the flanges (the ones
held in place by the bolts and nuts, not the bevelled flanges welded to
the pipes) begin to bend before you reach the lower limit of the torque
stated by Rotax. Do not apply more torque! The flanges (and the rest of
the exhaust system) are NOT Rotax parts, and evidently don't take the
Rotax stated torque without bending.
I checked this with Andy today: It is difficult to explain why Rotax
keep stating the torque when the nuts are check-nuts and therefore do
not require a minimum torque to stay put. The nuts should, according to
Andy, only be torqued to give a tight connection, to avoid exhaust
leaks. There is no proven need to torque more, the system will stay in
place even though this connection to the cylinder heads is the only
place where the entire exhaust system is anchored to the engine.
Andy will place a note about this in the next Tech Talk column in the
Europa Flyer, and in the f.w. forward manual at next revision.<
Although it seems unlikely the nuts can work loose. In the first year I
had one manifold (the front stbd) come loose enough to allow sooting of
the head due to gases escaping. It needed about 3 turns of the nut
before it even touched the flange. I know that I am not the only case
and have checked the nuts regularly since. The latest nuts are slightly
different (copper coloured for identification purposes) so might stay
put better. One thought is, if there is enough thread available, lock
the nut with an extra half nut.
Nigel Charles
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