Topic: 1978 CB750F_Stock Rear Sub-Frame or Weld on a Hoop??

[CB_Jeff]

I have a new to me F2 that the PO was trying to cafe, in general the bike is pretty clean and complete, should be a good project candidate.
The one issue that the bike has going that almost stopped me from buying it, was that the rear subframe outboard of the rear shock mounts was cut off... not a bad job, clean cuts.
Anyhow, I am at a point where I could either try to track down a stock sub-frame that someone removed from their project and weld one back on my this frame, or I could go the hoop route.  Not to offend anyone, but being an engineer, I have to think that the stock sub-frame may be a bit more robust than a hoop.
Also, I like the Aerotech F2 fiberglass seat, which may require a stock frame.
Any thoughts... and anyone have a cut off stock sub-frame?
I will post pics later as I don't fully recall all of my Photobucket login info at this time.
-Jeff

[Puntas13]

I cut the rear frame off my bike in the same place to weld a hoop. If its already done then just weld a hoop on or just leave it as is. The piece that's been cut off is just flimsy stamped metal so to me the thicker hoop seems more structurally sound anyway.

 I honestly wouldn't see an after market seat needing any point of the frame aft of the shock mounts. With the seat I installed there was actually a clearance issue with the stock frame and that's what prompted me to cut it off.

I've noticed no difference in the bikes handling with the rear frame cut off. And i still haven't even welded the hoop up.

[Djfob]

I welded a piece of 3/8 flat bar across the hoop mimicking the original rear section.

If the seat you like requires the stock frame then go that route. Either way will be fine.