Home › Forum › Ask A Member › Johnson 5hp TD20 ignition timing facts & figures? › Re: Johnson 5hp TD20 ignition timing facts & figures?
The reason I’m keen to learn the correct timing figures, is that when I measured the ‘problem’ motor, it seems to be firing at about 30′ ATDC at the lowest throttle setting. My main experience with 2-stroke motors is in motorbikres, and in most cases, older 2-stroke bikes are spec’d to fire at TDC, or with some advance.
Most 2-stroke bikes have no advance mechanism, though, and this outboard does – albeit manual via the speed control lever. But that said, I have never in my life encountered any engine that timed at 30′ ATDC at any speed.. the most retard I’ve ever seen was a very old 4-stroke engine that timed 2-4′ ATDC at full retard.