Seat Build w/pics

Since I can't do any michanical work, because I'm waiting for parts, I thought I'd do a little work on making a seat. This is what I've been able to accomplish in a couple of hours w/an electric knife. A good rule of thumb w/working w/foam is that it's better to work w/thicker foam because you can always take some off. The lighter foam is much less dense than the black foam and I expect it to crush down, severly, when I get a cover on it.

early carving

more carving

more carving

shaping continues

still shaping

1st approximation on bike

Why the big hump on the back? I know the road racers use it so they have something to brace against but why on a street bike? Do you have an angle grinder? With a cutting wheel attached it will work great to smooth out the seat. Much better and easier than trying to smooth it out with a knife. I just got done cutting down a seat for a customers GS450. I cut the big pieces off with a hacksaw and the spent about 5 min smoothing it out with the grinder.

The "big hump" on the back will not be a big hump when I cover it. The light colored foam is much less dense than the black foam, so I'm making it big now so that when I put the cover on it, it will compress into something that should be comfortable for a passenger. I'm using various foam that has come in packageing for some very delicate instruments, some is very dense and some not so much. I'm also trying to make it so that it gives me some lower back support, on longer rides, when I lean back. I don't have a grinder but I do have one of those "spiral saws" that has a 90 degree attachment for putting sanding/grinding disks on. Any idea what size grit I should get? Any other advice/ideas are very welcome.
Thanks for the reply

I don't believe it matters what grade you use.

Maybe one of the grinding heads I have will work. Thanks

I doubt that the grit size matters. It will be rotating so fast that anything will work. Try it on some left over foam first.