Frame issue

So for my winter project I decided to strip down the XJ to the frame and start again. Got the motor out and started wiping off some of the accumulated crud. On the left lower frame rail I feel something sharp on the tube. Look at it and it's cracked. Only thing I can figure is it sat for 8 years on the sidestand and water collected inside the frame rail and froze. Anybody have this before?

 

My left lower frame rail had something similar around the middle of the rail when I bought it. http://www.xjbikes.com/Forums/viewtopic/t=16212.html

 

i found a drain hole under the swingarm pivot cover that needed redrilled

 

Dude, I have the same long split, just forward of the side stand! WTF??

I am gonna have a welder weld it closed for me, but what's happening here?

I am suspecting that the bung holes on the front down tubes, if not plugged with bolts, allows\ water directly in and possibly it could freeze.

 

I think my frame tubes are open in the back, underneath the seat. I've heard of the drain holes but don't know where it's supposed to be (or if I closed it up when I had it welded shut), and for now, the bike's staying in my basement garage so I shouldn't have to worry about freezing again.

 

It happened to my 82 750 as well. I found it very unsettling. Sure water expands when it turns to ice, but to blow out the frame is crazy. In my mind that means that the water slowly rusted the inside out for any number of years, it got weak, it broke. So I began to wonder, where else on my frame is it weak. The location of the break makes sense, side stand down, thats the low point for water collection. Even up on the center stand water would collect there. But what about the other side? is it weak. Or what happed all the times I just parked the bike in my drive way and the front wheel was higher than the rear. The water would collect back by the swingarm. Ohh boy....
I ended up buying a frame off of a guy who also had a collector for me, the price was right, it looks better than mine. It could just be waiting to split open but who knows. I feel like I bought alittle more piece of mind and saftey. I will be drilling drain holes in this frame as well as plugging up the openings on the frame under the seat.
DRat

 

This was a common problem with the older Ski-Doo's trailing arm. A friend of mine had a good preventive fix for it.

He would drill small holes in the bottom of the tube. Make sure it is real dry inside, then spray "Great Stuff" expanding foam inside. Not only would it keep the inside from collecting water, it would also strengthen the trailing arm.

If you are doing a frame off resto, and not running the wiring through the frame, this may work.