Author Topic: CB500 cafe seat mounting help.  (Read 1630 times)

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Offline Cleric40

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CB500 cafe seat mounting help.
« on: June 22, 2015, 12:37:30 pm »
Hi all,

I recently ordered in a new seat for my build and I am hoping some of you can help with ideas on how to mount it.

My biggest issue is with the curvature of the frame relative to the straightness/flatness of the seat.  (See pics)There is a major gap from frame to seat. Also accommodating the front mounting near the rubber gas tank mount.  I plan to do a rear hoop also but before I cut up the frame more I was hoping for some help.

The seat is somewhat flexible but I don't think it could or should bend that much.

What have some of you guys done with mounting your flat seats? Suggestions? Looking for any help or ideas you may have to help finish up this project.

Thanks in advance


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Offline calj737

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Re: CB500 cafe seat mounting help.
« Reply #1 on: June 22, 2015, 12:51:19 pm »
That's my buffed beef with flat seats on 500/550 hoops, the damn curvature! A rear hoop welded on to straighten the hoop is easy enough, but you need to slide your seat back a bit from the tank to get better alignment with the hoop forward of the shock.

You will have a gap at the rear of the tank as a result  :-\ Its just the style of the tank I'm afraid.
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Offline SOHC4 Cafe Racer Fan

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Re: CB500 cafe seat mounting help.
« Reply #2 on: June 22, 2015, 01:54:07 pm »
If you want the front of that seat to sit lower to the frame rail, you will likely need to modify the subframe near the tank so the seat can drop down deeper -- looks like interference from the rear gas tank mount.
1975 CB550K1 "Blue" Stockish Restomod (http://forums.sohc4.net/index.php?topic=135005.0)
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1977 CB750K7 "Nine Lives" Restomod (http://forums.sohc4.net/index.php?topic=50490.0) - Sold
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Offline Cleric40

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CB500 cafe seat mounting help.
« Reply #3 on: June 22, 2015, 02:04:03 pm »
Thanks guys. I also thought about cutting the front of the seat a bit to allow it to sit lower.

Anyone who's mounted a flat seat on a 500/550 have any advice or pics?


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« Last Edit: June 22, 2015, 02:08:17 pm by Cleric40 »

Offline SOHC4 Cafe Racer Fan

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Re: CB500 cafe seat mounting help.
« Reply #4 on: June 22, 2015, 02:12:34 pm »
Think about the following. You probably want the line of the bottom edge of the tank to flow through to the bottom edge of the seat.  You can do this by forming a metal seat that folds over the frame reals and reaches down to meet the line of the bottom edge of the tank.  In doing this the lines of the bike will flow from front to back.  The folds of the seat will follow the frame rails so they will have some curve and then the seat pad will re-even the horizontal line. You can form you seat pad to be as thick as you want it, if you want to end up with a flat (brat) style seat pad.
1975 CB550K1 "Blue" Stockish Restomod (http://forums.sohc4.net/index.php?topic=135005.0)
1975 CB550F1 frame/CB650 engine hybrid "The Hot Mess" (http://forums.sohc4.net/index.php/topic,150220.0.html)
2008 Triumph Thruxton (http://forums.sohc4.net/index.php/topic,190956.0.html)
2014 MV Agusta Brutale Dragster 800
2015 Yamaha FZ-09 (http://forums.sohc4.net/index.php/topic,186861.0.html)

"There are some things nobody needs in this world, and a bright-red, hunch-back, warp-speed 900cc cafe racer is one of them — but I want one anyway, and on some days I actually believe I need one.... Being shot out of a cannon will always be better than being squeezed out of a tube. That is why God made fast motorcycles, Bubba." Hunter S. Thompson, Song of the Sausage Creature, Cycle World, March 1995.  (http://www.latexnet.org/~csmith/sausage.html and https://magazine.cycleworld.com/article/1995/3/1/song-of-the-sausage-creature)

Sold/Emeritus
1973 CB750K2 "Bionic Mongrel" (http://forums.sohc4.net/index.php?topic=132734.0) - Sold
1977 CB750K7 "Nine Lives" Restomod (http://forums.sohc4.net/index.php?topic=50490.0) - Sold
2005 RVT1000RR RC51-SP2 "El Diablo" - Sold
2016+ Triumph Thruxton 1200 R (http://forums.sohc4.net/index.php/topic,170198.0.html) - Sold

Offline Desert Dan

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Re: CB500 cafe seat mounting help.
« Reply #5 on: June 23, 2015, 02:34:46 am »
Just idle speculation here, but if you look at the curve of the frame compared to the curve of the seat it looks like the seat is backwards. Perhaps try rotating he seat 180 and see how it lines up, the end of the seat may not flow right with the tank that way but it may fit the frame better.

Offline Cleric40

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Re: CB500 cafe seat mounting help.
« Reply #6 on: June 23, 2015, 06:18:34 am »

Just idle speculation here, but if you look at the curve of the frame compared to the curve of the seat it looks like the seat is backwards. Perhaps try rotating he seat 180 and see how it lines up, the end of the seat may not flow right with the tank that way but it may fit the frame better.

Hi desert Dan, I actually did this! Haha. It does fit better but the seat kinda gets wider at the back so it makes it look weird having the wider portion up near the front of the tank.

I'm thinking I may need to just build a seat....  Anyone interested in a brand new seat?!


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