Topic: 1978 550 seat on a 1974 550 frame

[Greaser Greg]

Anyone know if this is a straight swap, or what is required to be changed to make it work?
Greg

[TwoTired]

78 tank is longer than than 74.  So, there will be a gap between 74 tank and 78 seat.
 Also, the seat grab rail will need to swap as well.

I suppose if you swap all three assemblies on top of bike, it could work.  But, then you get the large turn sigs on the back.

Cheers,

[Greaser Greg]

Thanks T.T.. I'm expecting a sweet 77 tank today! Nicest one I found at a reasonable price. Plus I prefer the shape. So, no issues with latch or hinge, does the grab rail interfere with mounting?

[Bankerdanny]

There are no issues with the latch and hinge, I don't know about the grab rail. The rail shape is different on the F and later K bikes, but I don't know about length.

Here's my old '77 K for reference. You can see that the turn signals are mounted farther back than on the earlier bikes.

[Bankerdanny]

This is the stock seat and rail setup from my 75 F

[TwoTired]

Thanks T.T.. I'm expecting a sweet 77 tank today! Nicest one I found at a reasonable price. Plus I prefer the shape. So, no issues with latch or hinge, does the grab rail interfere with mounting?

Hinge and latch should line up.  74 grab rail will interfere with the 78 seat, as the 78 seat extends rearward farther. Tlhinking more about it, the 74 tail light may get hit with the 78 seat, too.  The 78 grab may interfere with the 74 tail light, as well.  Its been a while since I tried the swap around. But, if you still want a stocjish look,  I think you'll want to shop for a 78 rear fender and tail light, too.

Cheers,

[Greaser Greg]

The seat arrived and it fits, mostly. The front edge is about an inch too long to allow the seat to lower completely without more pressure than usual being applied.  I don't have a grab bar.  Seems to be the aftermarket cover being installed over the original is part of the issue. Trimming the pan a little will make it better, I think. Whenever the gas eats through my current tank's one spot of bubbled paint I'll make my move. Thanks for all the replies.
Greg

[Bankerdanny]

The seat touches which tank, the '74 or the '77? With either tank no trimming of the pan should be required. A '74 tank is shorter than a '77 and the '78 seat is made to go with either a 550F or 77-78 550K tank.

[Greaser Greg]

I don't really know which seat I have, but the 74 style tank fits with it, and the "77ish" tank I got prevents the seat from closing by contacting the tank. There is no grab bar.

[Bankerdanny]

Then you have a 74-76 500/550k seat. It won't work with the 77ish tank because it is too long.

[Greaser Greg]

Hacksaw, plywood, carpet pad and boat seat vinyl time whoop whoop! Gonna get me some rear sets and clips ons, too!  Wanna buy some fenders an a air box?

[Scott S]

 What shape is the rear fender in?

 Better hold on to that air box....

 But if you decide to sell it, keep ALL of the random hardware bits and brackets with it. The air box is the easier part to find. People rarely keep all the mounting hardware with it.

[Greaser Greg]

The seat arrived and it fits, mostly. The front edge is about an inch too long to allow the seat to lower completely without more pressure than usual being applied.  I don't have a grab bar.  Seems to be the aftermarket cover being installed over the original is part of the issue. Trimming the pan a little will make it better, I think. Whenever the gas eats through my current tank's one spot of bubbled paint I'll make my move. Thanks for all the replies.
Greg

Meant to say the TANK arrived, not seat.  Oops!  Will not be any chopping, either. Just trying to ad some humor and troll a little. (Where's the "devil" emoji?). I like fenders and a regular seat.