Fred is correct, you have an Elto Special Speedster. The first year it was available was 1932, and 1932-33 was the entire life span of the model 905.
It used the same dual-knob flywheel as the Quad. They are a different sort of Elto. They are rated at 12 HP but some say a good 7 HP Service Speedster will outrun it.
Here is one that is owned by Rick Eichrodt
Hope it helps.
Best,
PM T2
He's livin' in his own private Idaho..... I hope to go out quietly in my sleep, like my grand-dad did..... and not screaming, like the passengers in his car...