250 cases?

[herman]

I have now had two motors split by a old penton dealer, one that was the one that came with the bike,(74)the other one was sent by the person who sold me the bike(He didnt even charge me for the second engine as he had no idea of the condition)and one thats 76. My problem is they both had pitted cases,the 76 a little nicer. Should i use the 74 so that the numbers match or the 76 that in better condition? And what do you do to stop the problem of this metal brek down or the pitting in these cases?Both had bad rods and the clutch in the 76 is totaly shot.Some one has to have a idea of how too stop the deteration of these cases. Thanks Herm Knoll

[dirtbike]

I really don't know! The magnesium is a bad material and can't stand water or moist. I came to think of a Kawasaki 250 I had before. When I disassembled the engine the cases where actually painted black inside too as well as the outside. The paint on the inside looked really good and didn't appear to be affected in any way. Frankly, it was shiny and bright like it was on the outside when new, I guess!

I don't whow what paint the use original but it seem durable. I would guess that carefully blasted cases could be painted with such a paint keeping the deterioration away for a while??

I have that scrapheap material in my 250GS cases too and I have the same problem. My cases are pretty good though but the signs is coming.

[Kip Kern]

Glas Bead blast the cases at 80psi, 60/80 grit glas,  brush paint the pitted area/s with Red Glyptal paint (available at Eastwood company) put it on thick in the pitted areas it will soak in and dry quickly.  Major magnesium damage you can have welded.  The key to magnesium is to keep it clean, dry, and painted.

[john durrill]

herm,
 Bobby Lucas has a man that built a cabnet just to weld up cases that have damage like you describe. he can also machine them back to origanl condition.
 John D.

[herman]

Thanks Al has told me to call Bobby too. So iwill try that tonight. Herm