Because it cracked on the weld when the guy tried to drive a ball bearing back into it's recess . It's obvious that the weld material mixed with the base metal , when it broke it took part of the base metal with it , leaving a crystalline-looking surface . Weld is very brittle , not at all like aluminum should be . I used 5356 the first time , but I also have 4043 on hand . I've considered buying some of that low-temp aluminum brazing rod to redo this ... this part is apparently difficult to replace , I've been looking around on the web and get conflicting data - some say it's the same , some differ . This is the outer right side crankcase cover on a 1987 CBR125R dirt bike .
- posted
10 years ago