My DA50 with ignition & prop bolts is 51.9 oz

The muffler (stack uncut) is about 5 oz (Mine cut was like 4.1 oz)

Custom 4.25" standoffs should be right at 6 oz. (close calc based on weight of 1.72" ones)

So we'll round it all to 62 oz or 3 lbs 11 oz... or ballpark 3 3/4 lbs

Keep in mind this is complete mounted to firewall... not sure what standoffs you might need to make up to mount the 75...

That's the 75iUS version with the side carb?