Topic: anyone ever put a flat cafe seat on a curved cb650 frame?

[81cb650]

The back of my 81 cb650 is curved up from the seat part to the fender, it has about a 1.5-2 inch rise at the rear shock. its not straight like most all the bikes from that era. And im looking to put a flat cafe style seat pan on it. So im thinking to just make a gusset that will fit in the gap that will be under the seat part. or maybe find a seat pan that will slide over the sides of the frame and hide the gap. but then it will still be hitting on the shock and creating a gap underneath. anyone delt with this? ive never used fiberglass so dont think making my own would be a good Idea, although it may come down to it. ill get pics up as soon as i can so you get an Idea what im working with.

[Triffecpa]

I did one on a race bike.  Just took a piece of angle iron that was about 1.25 x1.25 and laid a piece from the "hump" to the rear tank mount area.  I obviously put the flat side on the top and the other side of the angle on the inside of the frame.

Interestingly enough, I compared CB650 frames side by side with CB550 frames.  I thought that the seat area was lowered on the 650, but instead they raised the rear area which in essence dropped the rear of the bike.  So on my second 650 track bike I cut the frame just ahead of the shock mount and extended the seat area frame rails straight back and then eliminated the dropped area and raised the back of the bike up.

Tracy

[TicoCafe]

I did one on a race bike.  Just took a piece of angle iron that was about 1.25 x1.25 and laid a piece from the "hump" to the rear tank mount area.  I obviously put the flat side on the top and the other side of the angle on the inside of the frame.

Interestingly enough, I compared CB650 frames side by side with CB550 frames.  I thought that the seat area was lowered on the 650, but instead they raised the rear area which in essence dropped the rear of the bike.  So on my second 650 track bike I cut the frame just ahead of the shock mount and extended the seat area frame rails straight back and then eliminated the dropped area and raised the back of the bike up.

Tracy

I am having the same issue as for the seat area being lower than the back...I was thinking of the angle iron idea or also maybe use rount pipe to fill in the lower area to bring it up closer to the rear...

Did you have to re-locate/weld the shock mounts to the new area? Im assuming yes the way you are describing it.
Philip

[Triffecpa]

Did you have to re-locate/weld the shock mounts to the new area? Im assuming yes the way you are describing it.
Philip

yes.  I cut them off the stock frame arrangement and then using an old set of shocks for a jig (bolted the clevis end to the swingarm and the upper shock mount to the shock) I welded them back onto the new frame section.

Tracy

[65Ch3v3LL3]

You can also try to find a 79 650 frame. They are straight and look similar to the 750 frames.

[KingCustomCycles.com]

Doesn't the stock pan hump up in the rear and already have all the mounting and support points?  Modify the stock pan with a rear cowl, cut the foam to the shape you want, have a professional upholstery shop tidy things up for you.  I have done many "cafe" seat and cowl installations and I always like to use the stock pan if I can and modify it.

[TicoCafe]

You can also try to find a 79 650 frame. They are straight and look similar to the 750 frames.

That was my other option...older frame and it should be a straight bolt up....but no luck so far finding one in Texas. 
Looks like welding angle Irons to bring it up would be the best option for now.