Topic: adapting seat moutning from different year/model CB

[YogiBear]

My 750 was in need of a seat and my 500 had a stock seat on it. Im turning my 500 into a cafe racer and so I bought a cafe seat for it. I too kthe 500 seat and put it on the 750. However, im running into a littel snag. The 750 and 500 stock seats mount differently. Has anybody ever used a seat from a different year and/or model CB on another? Im kind of looking for options on making the seat work to flip open and mount correctly.  Thanks.


PS: my 750 is a 74 and my 500 is a 73.

[mystic_1]

You should be able to take the 500 seat apart and modify the seat pan.  Drill holes for the hinge mounts and the latch hook, and weld nuts to the inside of the pan.

mystic_1

[FargoFour]

I replaced a king/queen seat that came on my CB750K1 with a seat from a CB750K7. It was a chore since the K1 opens to the right and the K7 opens to the left.

I cut the hinges from the K1 and then cut the hinges and seat lock from a K7 frame. I then welded the new hinges and seat lock on the K1.

It worked OK. I got the seat positioned back a little too far, about a 1/2 inch gap between seat and tank. But it was nice to have a seat lock. I had to add about a 1/4 inch of rubber to the seat blocks since the seats seemed to sit at different heights.

I don't know if it was my fault or not but the I had to take the left side cover off to open the seat all the way.

The new seat looked good and rode fine. The ironic thing is that I ended up keeping the K7 and now need the seat, but I found a used K4 seat for the K1, so I have to cut and re-weld all the hinges again!  O well, a good winter project for up here in the north tundra.

So it can be done.

bud.

[YogiBear]

ok, well its good to hear that its been done. Im guessing that when the go to modify the hinges, youre using the stock hinges not something else? correct?

[westondc]

i'm not sure what the hinges look like on a 750 but maybe this would work... http://cgi.ebay.com/ebaymotors/Honda-CB750-Cafe-Racer-SS-Hinges--CB-750-SOHC-Kit-K0-K6_W0QQitemZ270473639583QQcmdZViewItem?rvr_id=&itemid=270473639583

[YogiBear]

i'm not sure what the hinges look like on a 750 but maybe this would work... http://cgi.ebay.com/ebaymotors/Honda-CB750-Cafe-Racer-SS-Hinges--CB-750-SOHC-Kit-K0-K6_W0QQitemZ270473639583QQcmdZViewItem?rvr_id=&itemid=270473639583

I like the looks of that kit. Thanks.  $30 seems a little high though. That might make my endeavor easier however.

[mystic_1]

Sounds like FargoFour modified his frame to fit the seat.  I recommend instead modifying the seat to fit the frame.


The linked hinges will work great, they are stainless steel hence the price.

mystic_1

[FargoFour]

I cut the old hinges off the 71 and welded on the hinges from the 77.

A pain to be sure but I thought I was going to keep the 71 and sell the 77 to some guy that was going to cafe it and said he didn't need the seat. That sale fell through and so I kept both bikes. I then came a cross a 74 seat at a GREAT price and so here I am putting everything back to the way I started. Gotta learn to think ahead!

Anyway, it can be done but like mystic_1 said it may be better to mod the seat than the frame.

bud.

[Ricky_Racer]

i'm not sure what the hinges look like on a 750 but maybe this would work... http://cgi.ebay.com/ebaymotors/Honda-CB750-Cafe-Racer-SS-Hinges--CB-750-SOHC-Kit-K0-K6_W0QQitemZ270473639583QQcmdZViewItem?rvr_id=&itemid=270473639583

The hinges on the CB500/550 and CB750 K0-K6 are very different: the 500/550 uses one long hinge on the left side with two studs 75mm apart. The CB750 K0-6 uses two hinges on the right side, each with two studs 27mm apart. The CB500/550 seat pan is also slightly wider than the CB750.

The stainless hinges won't help you very much; they are made to the same measurements as the stock CB750 K0-6 hinge. Where they really come in handy is as a dress-up replacement for the standard hinges, or as an excellent solution for mounting a fiberglass cafe racer seat pan to a CB750 since the hinge plates mount through the pan and sandwich the fiberglass between the two components. 

Good luck on the conversion. Trying to mount a CB500/550 hinge and lock on a CB750 factory pan, or visa-versa, is a ton of work and takes a lot of trial and error fitting since the pans have a different profile. You're probably better off looking for a factory seat to fit the frame you want it to fit.    RR