Any ideas on this...

How to lower the rider seat keeping the original one....I think to cut some foam off the seat, but once started there is no going back and it's really not easy to find parts here so I do not want to mess it up. Someone did it before?
The reason I want to to keep the original seat is because I bet once some foam is remove you'll have a very good support for your lower back with this design... plus I won't need to cut nothing... Any ideas?

 

That's what I did a few years ago, no write up or pictures but here's the details:
1. Carefully remove seat cover, it is stapled down to the plastic seat pan (my original cover was in nice shape so i wanted to keep it)
2. Traced profile with sharpie and ruler to keep lines straight and spaced appropriately
3. Cut out desired sections with knife and sanded down with a wood file and some medium sandpaper
4. Once i got the desired shape and height, i covered with some plastic window covering, 2 layers i believe. I used something like this, http://www.amazon.com/3M-Indoor-Window-Insulator-5-Window/dp/B00002NCJI
Not sure if it was needed or not but thought it would help with waterproofing the foam. I basically heated it on there tight with a heat gun
5. Use adhesive to stick the seat cover back on, and then fasten it to the seat pan. I ended up using a high powered staple gun with really short staples but it was a PITA.
I ended up cutting about 1" from the lower portion of mine out, and trimmed the sides down a little too. Left the passenger area intact and recovered with the original cover. Still looks stock and it does give you a little more support from the passenger seat as you mentioned. Good luck

 

If you mess up or just want some firmer padding get some scraps of carpet pad.
You can stack it up and make a whole new seat if you want.

 

Look at my xj700 in the gallery, then look at my xj700 pseudo-mod in the gallery---- same bike, different clothes. Seat is an oem pan, foam, and cover. Just cut down and re-shaped. The original seat goes on the shelf when set up as the pseudo, so the bike's own original seat stays intact. I picked up another one from eBay to modify.

 

Hogfiddles, I saw that bike in the gallery I even post a messege for you asking if you can explain me the process, How you did it with the seat...

 

1. I bought an extra seat on eBay
2. Unstapled the seat cover
3. Heated and re-shaped the pan
4. Re shaped the foam with a hack saw (fine teeth make smoother cuts in the foam) files, and sandpaper
5. Re-stapled the seatcover back on.

 

This might help:
http://www.diymotorcycleseat.com

 

Getting an used seat is not an option, because there is none walking around and will be too expensive for me plus the "thing" with customs here even if you buy in internet. That's why I do not want to mess it up...
Thanks K-moe, I already started to read the whole site.

 

Go slow, and check the "feel" VERY OFTEN. You'll be fine.

 

Thanks Hogfiddles....

 

"The reason I want to to keep the original seat is because I bet once some foam is remove you'll have a very good support for your lower back with this design... plus I won't need to cut nothing... Any ideas?"

Bike ergonomics (how YOU best fit to the bike) is determined by your preferred riding style and your body measurements. Typically, most people find that a "standard" riding posture/style works best for most riding as you can still use your legs to cushion road bumps, your arms do not tire out early because your forearms are in a pretty much horizontal position, and your body is in about a 3-5 degree lean into the wind (unless you plan to also have a fairing mounted) so you avoid excess neck bend. Another big influence on riding comfort is seat width; too narrow a seat is uncomfortable regardless how much or what type foam you put on top (see: the DIY Motorcycle Seat site). I seem to prefer the ergo layout found on many "dual-sport" bikes, but I'm 6' 2" and my knees and back do not bend like they used to so I tend to prefer about an 80 degree knee angle (or better), and my feet slightly in front of my hips. You don't say which XJ you have, but on http://cycle-ergo.com/ you can select a bike (they have a couple XJ Secas, but no Maxims - but the Maxim positions are very similar to the Seca), plug in your body dimensions and see how "you" look. You can then mod the bike (seat height, bar pull-back and height, etc.) to achieve the fit desired.
More research material (in addition to the excellent DIY Motorcycle Seat site):
http://www.motorcycledaily.com/2012/03/upright-ergos-the-new-trend/
https://prezi.com/0nneqyc0kb2u/ergonomics-motorcycle-riding-posture/
http://blog.jafrum.com/2013/08/07/how-to-avoid-back-pains-on-your-motorcycle-ride/

 

Zap, thanks you... I'm also 6'2"about 110 kg. I'm not saying my maxim (xj700 '85) unconfortable... but for long rides I'd like to place my legs further than they already are...It's an awesome position to ride but after 3 or 4 hs I get tired specially in winter weather...