I finally got my hands on an old 73 cb750. Got it pretty cheap so I jumped at it. I started to tear it down today and thought something looked funny. I took of the tank and noticed the two spars underneath the main tube(underneath the tank) were chopped back to the beginning of the seat mount. Not worried about looks here but has anyone done this? Any opinions on the integrity of the frame without these supports?
Cut frame question- opinions please...
- Thread starter cafeguy78
- Start date
killerdwarf
Been Around the Block
fix it, or replace the frame. That looks pretty weak, and flexable to me.
The reason this is done is so you can pull your head off without having to remove the whole motor.
Go search around here: http://forums.sohc4.net/. there is a guy who builds (or at least built) a bunch of "kits" that made your missing section a removable/replacable section.
You do need those bars for frame support and integrity however. I wouldn't recommend very much riding without them.
Go search around here: http://forums.sohc4.net/. there is a guy who builds (or at least built) a bunch of "kits" that made your missing section a removable/replacable section.
You do need those bars for frame support and integrity however. I wouldn't recommend very much riding without them.
rockcitycafe
I make things.
the welds will be a strong point actually, if done right... I wouldn't do this on anyone's bike but my own just for the liability, but here's what you do:
find the appropriate size steel pipe, nothing fancy, that frame was just mild steel, then find smaller pipe that will provide a good slip fit inside the larger pipe. cut the smaller pipe in 2" lengths, cut the larger pipe to fit the missing sections minus about 1/4", drill two holes 1/2" from the end of the missing section, and from the ends of the new pipe, fit the pipes together with the inserts in the ends, plug weld the inserts, tacking the pipes in place before heating causes anything to move around, then do the final welds, which will end up as a butt weld with a backing "plate" (pipe). this will be stronger than it was before, which is what you want
find the appropriate size steel pipe, nothing fancy, that frame was just mild steel, then find smaller pipe that will provide a good slip fit inside the larger pipe. cut the smaller pipe in 2" lengths, cut the larger pipe to fit the missing sections minus about 1/4", drill two holes 1/2" from the end of the missing section, and from the ends of the new pipe, fit the pipes together with the inserts in the ends, plug weld the inserts, tacking the pipes in place before heating causes anything to move around, then do the final welds, which will end up as a butt weld with a backing "plate" (pipe). this will be stronger than it was before, which is what you want
Appreciate the help. I am also looking into the removable section to fit in there. I am going to go to a shop today and talk with them and see what their take is on the subject and how much this is going to set me back. Can't wait to get into the motor and see that that the cam chain is actually being help together by a paperclip or something or how else it's rigged. I'll keep ya guys updated.