KZ750 LTD seat foam

I've got an 82 kz750 ltd with an aftermarket seat which looks nice but is far too short for me. My hips and knees get sore after 45 minutes of riding. I'm thinking of getting a reproduction LTD seat cover from Z1 enterprises, get some high density foam and rebuild it like a stock seat.
What I don't know though is how thick I need the foam to be to fill the cover. Can someone with an LTD seat get me a rough measurement of the foam thickness? 4-5"?

I don't have the original upholstery on mine, but I'm pretty sure the foam was stock when I got it (it has since been replaced but has the same size and shape). I can measure it tomorrow if you want.
It has virtually no miles since the seat was redone so it hasn't been sat into submission yet.

Here are some pics of a 1982 750H Ltd seat that I recovered. measurements:
Fr rider section = 5-1/4" thick at center of seat. hooked tape measure at bottom edge of seat directly above the side cover emblem.
Rr passenger section = 6". measured from bottom edge of seat directly above the frame grip bolt hole.
Rear of seat = 5". measured from bottom edge of seat directly above Rr fender to seat cover trim.
note: first 2 measurements, laid straight edge across seat to get thickness of center. Fr section of seat has quite a bit of arch to it.






1981 KZ650-CSR w Ltd seat. the csr has the same seat as some of the 750H models.

Thanks Martin, I forgot that they did away with the two piece seat on the Ltd.

Cool, thanks for the info guys. I have a suzuki dr650 gel seat laying around that I might cut up for a top layer. Here's the current seat:

If you need any more measurements, let me know. The rear pillion is pretty easy, especially from the bottom edge to the trim. The passenger section has about 1" of arch, so the sides are about 5" to the trim. it varies by about 1/8" either way.

Can you tell me how far up the tank the nose rises? I got all my materials and this is the current mess. I might need another layer of rebond, definitely in the rear. Each layer is 1". Comfy so far!

From rear of tank to where Fr seam of seat contacts fuel tank = 4-3/16"

From front edge of seat to Rr of fuel filler cap = 10-7/8" .... maybe a tad less (the tank is curved, so it isn't a straight-forward measurement).

ps: is that multi-colored foam suitable for a motorcycle seat?

The rebond foam was recommended for powercraft seats because of how resilient and dense it is. That said, it was a pain to shape! I also used some dense boat cushion foam a coworker gave me and the blue stuff is the softer top layer. I probably went about it the hardest way but somehow it all worked out under the cover. It passes the ten foot test at least and it made the bike so much better to ride. No more tensing up at the sight of a small crack in the road. I don't get why people want to beat themselves up on cafe racer seats, I just want to ride for hours.

It came out pretty darn good.

That speckled foam looks like a carpet pad, that's why I asked. hee.

Never heard of anyone using it, but boat foam should be perfect.