” Do you want us to give you a ride home? “
Such were the joking words of one of Jan Johansson’s fellow pilots, participating in the 2024 Fly-In at Blokhus Beach, Denmark. The reason was that Jan had been trying to convince the de Havilland Gipsy Major engine in his beautiful 1946 SAI KZ-II Trainer to start for more than an hour – his arms already pretty sore.
The Gipsy Major is a 145 BHP naturally aspirated in-line-four aero engine produced in the 1930’s. A total of 14650 Gipsy Major engines has been built, and they have been widely integrated in many aircraft designs. Beside the SAI KZ-II, the Gipsy Major is also found in de havilland DH.82 Tiger Moth, DHC-1 Chipmunk and Auster Autocrat to mention a few.
Right: BTH Magneto
The stock Gipsy Major engines utilize two BTH magnetos as independent ignition systems – one with an impulse coupling used for starting, and one without. The magnetos rely on the magnetization of its permanent magnet to be able to create sparks. Among other things, it is this magnetization that has a tendency to decay over the many years of operation, and that cause many of the starting issues of the Gipsy Major engines. The BTH is a bit sophisticated compared to other magneto brands, such as Slick or Bendix magnetos, as it allows for variable timing through a retard-linkage system connected to the throttle handle of the plane. This allows for lower ignition advance angles as low engine speeds and a smoother idle.
In June 2025 Jan was planning with some of his buddies to fly the KZ-II from Denmark to the vintage fly-in called “Hahnweide Oldtimer Fliegertreffen” in Germany. He decided that something had to be done to increase the ignition reliability of the Gipsy prior to the journey, so he approached Drino for guidance. After a bit of sparring Jan decided to go for an electronic ignition system, with an adaptor that would fit his Gipsy Major.
Over a few days, the CVI-4 with the Gipsy Major adaptor was retrofitted to the plane in July, and once timing and finalization checks was done, the KZ-II was ready for its first test flight with its new ignition system.
Prior to the first flight Drino received a phone call from Jan:
” What a difference!
She now starts in the second turnover after priming, when cold.
Three turnovers when hot! “
After the successful first flight with the new ignition system Jan made a shout-out recommendation to all fellow pilots having trouble with BTH magnetos. The post is in Danish, so we have taken the liberty to translate.
Not and “RV-smile”, but a “Drino-smile” 🙂
Yesterday I testflew OY-FAT with newly installed “Drino – Reliable Aircraft Systems” ignition system.
Now it starts on the second turnover, so what could be better?
Big thanks to Strut Nordjylland and Knud Johannson for the help, and to Claus Vad (DRINO) for the sparring.
And to all of you with BTH-magnetos: Buy Drino before your neighbor – that will get you in the air swiftly.
The week after Jan participated in the Blockhus Beach fly-in again, this time having no troubles with starting the old Gipsy, making the trip much more enjoyable. Here’s a few pictures from the day at the beach with magnificent weather.
The KZ-II is now ready for the trip to Hahnweide, Germany!
We’re glad to have been of service Jan!
Safe Flights!
Best regards,
Claus Vad
Founder of Drino – Reliable Aircraft Systems.