try atcheaven.com or if you just have a nice rider your putting it on and dont care about it being perfect there is always local upholstery shops that will cut you a piece of foam and even stretch your cover on for you. Last year I has a 185s 1983 seat completely redone and they used their cover. It was just a plain black cover but they only charged me $40 out the door.
I hope this helps and welcome to the site.
R.I.P. John Swinehart
TRIKEFEST 11, 12, 13, 14, 15, 16, 17, 19
Epic Mikfest 17
86 200x
85 250sx
85 big red
85 atc 70
Fabiodriven- cereal goes in first, then milk.
I’ve got an 8” Grip on a 10” turd... Kyle Kiser