I’d like to know if it’s true that a Rotax Max FR125 pre-Evo junior has lower porting than a senior, which would make it slightly more powerful at low revs. A good mechanic told me this, and I somewhat believe him, although sometimes I have a slight doubt because the track I ride is small and winding, with a single straight where the exhaust valve can open a little on a senior, and I’m quite efficient, sometimes even more so at low revs than a senior. In comparison, I’m more of a gear person, 82-11, and the seniors 84-11. I tried 83-11, and it’s less good, too powerful for anything at low revs, and it loses a bit of lap time. If anyone can tell me if this is true, please explain what they mean by lower porting, I think from the exhaust and the rest.
And is it true that I only have to change the cylinder with an exhaust valve, to put my Rotax Max Junior in Senior. Nothing else and everything else will be ok!
Thanks!