Rotax Illegal ECU problem

Hi everyone, I’m looking into what’s going on with illegal Rotax ECU’s still out there in the sport. I have heard about a Gen 1 and Gen 2 Rotax ECU and what I understand is the new Gen 2 ECU’s don’t rev the engine as high as the previous Gen 1 ECU’s. Is there a way to distinguish between a Gen 1 and Gen 2 ECU besides using the ECU tester via a serial number or some kind of reference? Both generations still use the same part numbers and the problem now is that only a tester can identify it.

The current part number for the Senior/|Micro ECU is 666815, and has been for about 4 years. So if you are running a 666815, regardless of its age, you are not running anything “illegal”. I have ECU’s from day one of the 666815 series, and don’t see any difference at all in power or the ability to rev. Getting a Rotax to rev over the limit (hitting “turbo” as people call it) is a function of jetting and gearing. On tight tracks where we have to stack teeth, we can see 15k on our Seniors, on both old and new 666815 ECU’s. That said, our goal is never to hit high rpm’s, it’s finding the smallest rear sprocket that gets us out of the slowest corner and keeps the engine in it’s ideal powerband the longest.


I’ve a programable cdi in my senior max. The guy that supplied me ( eastern europe ) sells various igntions for motorbikes etc.

But what he used to do with the old rotax, was programe the cdi and install it in the standard coil for some guys in europe.

I can imagine its easy done now with the standalone cdi box.

Funny thing I’ve actually never driven it with the cdi, had the engine ported and fully rebuilt with a new ignition curve and then never drove it. I moved onto KZ. Rotax just doesnt do it for me anymore.