Topic: Are 1977 CB550K3 seats different from earlier CB550Ks?

[cb_n00b]

Hi All,

Long-time lurker here. My buddy has a seat from Motorcycle Seats Direct that they sent him for his 76' 550F but it doesn't fit because they sent him the seat for a 550K.

He says I can have it, but would a '74-76 CB550K seat fit a '77 CB550K? Or are the seat mounts/pan different? Thanks!

[Scott S]

 Technically, it'll "fit", as in bolt on. But the '77 pan is different and it doesn't match up with the tank correctly.

[jonda500]

Technically, it'll "fit", as in bolt on. But the '77 pan is different and it doesn't match up with the tank correctly.

-so you wouldn't be able to close the seat as the rear of the tank would be in the way - exactly the same problem your buddy had with it!
John

[cb_n00b]

Technically, it'll "fit", as in bolt on. But the '77 pan is different and it doesn't match up with the tank correctly.

-so you wouldn't be able to close the seat as the rear of the tank would be in the way - exactly the same problem your buddy had with it!
John

Well the problem with his is that it's too big for his bike; the 550F seat is shorter than the 550k. I don't think there's going to be a tank clearance problem, I'm mostly just concerned if the brackets will bolt into the same places. Other than the way the gas tank cap is placed, the '77 and earlier model 550K tanks are almost exactly similar.

[jonda500]

I have the 3 seat and 2 tank types. (77-78 'K' tanks are the same as 'F' tanks except for the petcock):

- the 71-76 'K' tanks are smaller (14 litres) but will fit on to a 77-78 'K' or a 75-77 'F' (leaves a gap between the tank and the seat)

- the 71-76 'K' seats have the hinge and lock striker mounting points further back on the pan than later models so wont fit straight on to 77-78 or 'F' models because the seat wont close with the later model tank in place
 
- the 77-78 'K' and the 'F' seats are both similar - and have the mounting points further forward than the 71-76 'K's but these will fit on to a 71-76 'K' (and will leave a gap between the tank and the seat)

- the 77-78 'K' and all the 'F' tanks are bigger (17 litres) so can't be used with 71-76 'K' seats

err, there you are - as clear as mud now??
John

[cb_n00b]

I have the 3 seat and 2 tank types. (77-78 'K' tanks are the same as 'F' tanks except for the petcock):

- the 71-76 'K' tanks are smaller (14 litres) but will fit on to a 77-78 'K' or a 75-77 'F' (leaves a gap between the tank and the seat)

- the 71-76 'K' seats have the hinge and lock striker mounting points further back on the pan than later models so wont fit straight on to 77-78 or 'F' models because the seat wont close with the later model tank in place
 
- the 77-78 'K' and the 'F' seats are both similar - and have the mounting points further forward than the 71-76 'K's but these will fit on to a 71-76 'K' (and will leave a gap between the tank and the seat)

- the 77-78 'K' and all the 'F' tanks are bigger (17 litres) so can't be used with 71-76 'K' seats

err, there you are - as clear as mud now??
John

John - Thanks for the info - I think I'm following, but it sounds like based on bullet #2 that a seat designed to fit an older model "K" won't work with a newer model because the hinge and lock striker mounting points are further back than they are on a '77...Right?

Also - Can't believe someone knows all of this detail...Very impressed.

[jonda500]

"a seat designed to fit an older model "K" won't work with a newer model because the hinge and lock striker mounting points are further back than they are on a '77...Right?"

Yes, that's correct. It's because the newer tank is slightly longer (the mount tab at the back is recessed under the rear of the tank so it ends up in the same position on the frame as the earlier tank.
John

[Scott S]

 I don't know about that....
 I had an earlier seat on a '78 for a skinny minute. It bolted up and worked, but the length was wrong. I can't remember now if it was too short in the back, didn't match the tank correctly, etc., but it definitely "fit". Just not well.
 





 That said, go for the '77-78 seats. They fit much better for those frames.

[jonda500]

Well I can't understand that - I have both later model K and F seatpans and they are both missing an inch and a half of pan forward of the mounting points relative to an earlier seat (in other words they both have the mounting points positioned 1.5" closer to the front compared to the early model seat).

Here's pics of a later model pan and an earlier model seat
John

[Bankerdanny]

You can use a 77-78 K seat on any 550, but will have a gap between the tank and seat when using a 74-76 K tank.

You cannot use a 74-76 K seat on a bike with a 77-78K tank or 75-77 F tank because the seat is too long.

[Bankerdanny]

This is what an early K seat looks like fit to an F model bike. Without the tank the seat hinge and latch work just fine.

[jonda500]

Maybe the PO of Scotts skinny minute bike ('78 that has an early seat with a gumtwo cover on it) moved the hinge and latch forward a little...
John

[Scott S]

 Actually that's a '77 seat on a '78 frame on the black bike.
 That's the same bike with original paint and a pre - '77 seat in the other pics. It bolted up and latched but wasn't the right length.