Does anybody in the USA know what the stage 1 download really does? Harley EFI & Harley Carb Discuss Does anybody in the USA know what the stage 1 download really does? in the Harley Tech & Harley How-to forums; I've posted this question on other sites and have never seen a definative answer, just opinions.I know about the increased redline and I know that the download is specifically designed ...

I've posted this question on other sites and have never seen a definative answer, just opinions.I know about the increased redline and I know that the download is specifically designed for SE slipons/SE air filter, but what does it change in the ECM?This must be one the most closely guarded secrets in the USA rivaled only by the UFO phenomenom.

[47knuck]

Originally Posted by RAWHIDE

I've posted this question on other sites and have never seen a definative answer, just opinions.I know about the increased redline and I know that the download is specifically designed for SE slipons/SE air filter, but what does it change in the ECM?This must be one the most closely guarded secrets in the USA rivaled only by the UFO phenomenom.

Because the new Harleys are set up to run very lean (hello EPA!) when you let an engine breath in (air cleaner) and out (exhaust) better it would get even leaner, so I'd bet the the change would be to fatten up the mixture.

[Wrightturn]

Just a guess but either richen the mixture or retard the timing. My bet is to retard the timing to stay EPA legal. Is the bike really faster ? Wouldn`t be the first time that SE parts don`t scream.

[PeterV]

A good discussion. clicky here

[hdnt1550]

The download changes the program in the stock ECM with a new fuel map but I believe it still runs to lean.