Misfiring on 1 & 4
Aircraft is an Ikarus C42. Rotax 912-UL
Symptoms are misfiring on no 1 & 4 cylinders. Occurs whether on mag1 or mag2.
All wiring has been resistance checked.
'Black Boxes' have been swapped out with another engine. Continuity carried out on all wiring. All ok.
Changed all triggers, checked all pins in plugs for corrosion, swapped the stator wires from 1 to 2, swapped coils from 1 to 2.
Compression check on all cylinders - 140 to 160 psi.
Rocker covers removed for broken valve springs etc.
Checked all wiring to mag switches.
Replaced spark plugs with new ones.
Removed plug caps and resistance checked coils and caps. All ok.
Still same fault on cylinders 1 & 4, misfire, rough running. Removing plugs 1 & 4, both black.
Any ideas as what more can be checked before paying $$$ for stator or new coil to see if this is the problem.
Thanks in advance
Michael