swa45 wrote:
I strongly suspect that this BGM 24T straight cut clutch gear will mate with a Malossi 63T straight cut primary, but Scooter Center/BGM say otherwise:

https://www.scooter-center.com/en/clutch-sprocket-bgm-pro-vespa-cosa2-px-1995-bgm-superstrong-superstrong-cr-for-62/63-tooth-primary-gear-straight-24-tooth-bgm6224g
That makes it look like BGM and DRT are compatible.

I have a short 36 tooth 4th and DRT 24 tooth cosa 2 clutch cog. With the 24 tooth, 1st doesn't seem to short and the short 4 th gear doesn't have the 3 - 4 shift gap I noticed with my 177 motor.

Maybe try a DRT 24 tooth clutch cog and see what you think?