Topic: 77 CB400F frame welds

[rluser]

rickmoore24 inspired me to inspect the frame of my 400 more closely and newday777 showed me the nature of the particular problem with a 750 example.  That cause me to notice that my frame has welds that look like this.  Notice the end is not closed.  Did Honda not weld all gusset edges in 77? 

[calj737]

There’s no benefit to welding the top of that closed. With it open, it can also allow moisture to drain out. The strength is in the latitudinal welds along the tube.

[Quattrocilindri]

Watch out for the weld integrity on the side stand lug.
Back in 1975, on a relatively new 400F I had, the weld cracked. I saw it again in a 1976 400F that I was interested to buy a couple of years ago; when on the side stand, the bike leaned about 45 degrees on the left, and a 1/4" weld  gap on that lower frame tube was visible at the lug!! 
I never bought that bike, because it meant that the motor would have to be removed to get access to a repair weld without melting the engine!

[rluser]

rickmoore24 suggested the possibility of frame rot from the inside out in that region

[Alaxy Galaxy]

Watch out for the weld integrity on the side stand lug.
Back in 1975, on a relatively new 400F I had, the weld cracked. I saw it again in a 1976 400F that I was interested to buy a couple of years ago; when on the side stand, the bike leaned about 45 degrees on the left, and a 1/4" weld  gap on that lower frame tube was visible at the lug!! 
I never bought that bike, because it meant that the motor would have to be removed to get access to a repair weld without melting the engine!

The side-stand mount was changed for the 77 model year to strengthen it. The tab was bent 90deg in front to prevent bending and a plate was added to beef up the mount (as seen in the picture).

The 76 and 75 bikes have a simpler mount welded directly to the frame tube, which is prone to detaching.