I'm just resurrecting my 86 Honda CR125 and encountered something new to me. Many years ago I did clutch plates and perused the water pump. I figured I saw a bit of cavitation damage, not too bad, and forgot about it. Fast forward 20 years and bike stops holding coolant. Turns out the clutch side cover, which has the water pump, is made of magnesium, not aluminum. Two model years later they apparently reverted to aluminum. Why? Because the cover ate itself, corroding. Apparently its the lowest guy on the totem pole and gets sacrificed.
So the fix is clean and JB weld the missing metal.
Anyone else encounter something like this?
By the way, buzzing up an mx 125 and perking up the neighbours briefly - priceless. Score 1 hooligan point.