Does anyone know what the rear shock sag should be on a 1984 TY 250 mono?

My 220 lbs [ rider and gear ] gets alot of sag, about 50% of shock travel. The shock only has reboud adjustment and no sag adjustmet. Did yamaha offer heavier springs for these bikes as an option?

Thanks.

They do have preload adjustment though, there are two rings that lock against each other, are they done up to the stop?

I'm only about 175lbs, so with gear about 190lbs I reckon, and it sags loads and bottoms out all the time, my rear mudguard always has marks on from where the tyre hits it.

I'd look to go for a significantly stiffer spring, then you can play with the preload adjustment.