can someone please chime in on the possible negative effects of frame strengthening via gussets and downtube welding? i've heard it can cause the frame to actually "pull" itself apart because it's not allowed to flex like it was designed to. certain parts are more rigid leading to stress concentrations at the points of the gussets and possibly causing failure? i've love to add some strength to mine to help the handling out as much as possible when i get around to building the frame... good thread, great pictures!!
First lets quantify the real risk. NO ONE in my experience has ever had a CB750 frame fail. Gusseted or no. An occasional crack or weld separation is going to be within production expectations. Any one else have expereince otherwise? Was it the direct cause of something that was done to the frame, or a statistical outlier?
Theoretically, anything you do to stiffen one area will show weakness at the next point. If you can ride hard enough to feel that next weak spot, more power to you. Obviously the racer guys are on top of this.
The main points are above the swingarm pivot, the 2 spots (on each side for 4) under tha gas tank, and welding up the gusset where the headstock enters the downtubes. Quick simple, yields results, I daresay no downside. All the normal caveats about experienced welder etc. Only the biggest baddest racer with tons of HP and high banks etc. can feel problems beyond that.
Further triangulation in the area where the airbox would go, and the area between the front downtubes and above the front motormounts, would make it seriously stiff, but likely more than we'd ever notice on the street.
Or so I think.
PS: Oh yeah throw in some of Rob's motormounts!
