Cutting off rear of frame, any problems?

I am putting a short rear fender on my bike and was wondering if there is any downfall to cutting off the rear hoop portion of the frame that supported the rear fender? Would I need to weld in a new brace or would it be fine to cut off and cap the frame tube? This is a 78 kz650 sr and I will not be carrying passengers so there will not be any weight on the tail section.
Thanks,
KC

I would weld in a new brace for peace of mind.

I wouldn't take anything off a frame without bracing. It's just putting your safety on the line. Stress is carried in many ways in a frame. It's like which is stronger a roll bar or a roll cage? If you must cut it at least brace it. These frames do an amazing amount of flexing just look at how many floggers brace and gusset their frames just to get extra stiffening. Flex and welds are very bad things. Metal fatigue will take out anything and sometimes suddenly!

Ok, just wanted to check, I have seen some hondas without anything more than the sheetmetal bridge across the back where the seat pan rests. I will weld a crossmember in, just need to clear the tire and the taillight. Thanks for the replies.