Topic: Just found a big hole in the bottom of the frame!! Need advice

[inv3ctiv3]

There is a huge hole in my frame!!!! I don't know how I didn't see this before but it looks like it maybe had rust and someone cut the frame to get rid of it I don't know what to do about this, what do you guys think? I had no intentions of taking this down to the frame but now I feel like I have to in order to fix this and at that point I might as well powder coat the frame...Can this be fixed? Is it worth fixing?

[PeWe]

Acid leak from battery? When bike has fallen the battery can leak thru the vent hose. I have sealed battery, GEL type.
CB750 had a Service Bulletin about that.

Bike apart, weld it, check for more holes and paint the frame into good shape

[MoMo]

see my post on cause and repair in your other thread

[oldbob]

My first CB400F had some pretty wild looking repair in that exact spot. It seems that the 400 frames were a bit weak there. Imprudent side-stand use can cause the failure that you are seeing. I talked to with Charlie of "Charlie's Place" and he told me that it is a common and easily repaired problem.

I didn't repair mine. Instead, I sold the bike (after showing the area in question to the eventual buyer) and bought a cleaner example. After having the second 400's frame powder-coated, I left the side-stand off.

Bob