A FrankenFour Inline?


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Well-Known Member
Oct 31, 2005
Evans Head Australia
I did a lot of experimentation with the G10, I bought a Suzuki conversion built by Bilsam, who have long ceased business. The engine was a modified G10 tilted over at 70deg with a gearbox reduction 2.2:1, they never got the fuel injection to work so I used a Bing cv carb. After running the engine for a fairly short time I found that the rubber blocks that were used for torsional dampening were being dissolved by the gear oil. I discarded the gearbox and bought an SPG 2.
The SPG2 was quite heavy and the lighter starter of the Bilsam didn’t fit. The SPG was robust but the upright position of of the motor didn’t suit my installation. I built another sump and laid the engine over at 90deg, it ran fine but if the lean was anything greater than 90deg, oil was thrown out of the breather on the valve cover - I could have run it like that if I had fitted a reasonable dia tube between the valve cover and the sump to return the oil.
I found the best position for the flattest cowl was the engine at 70deg lean and about 45deg on the gearbox.
I then built an adaptor for the Rotax “E” gearbox, the drawings were for the upright install but I drilled it for the 70deg/45deg and tested it like that.
As I said the engine had been modified by Bilsam - raised compression, cam grind - the results I got were very promising, the G10 could turn a prop set for my Rotax 618 at approx the same revs at the same gear ratio, so it was producing almost the same power. I ran the engine for many hours on the test stand and it ran flawlessly.
At this time I was offered a very cheap overhauled 912 so the Suzuki was never installed.