85 CR250 water pump repairs

[ideasman]

Rebuilding an 85 CR, has the standard corrosion issues (rather severe) in the magnesium casing, I have repaired this type of pitting with success in the past, however someone has had a go at this in the past with something that looks like superglue and sand. My question is how to best remove the remnants of the old muck. I am considering sandblasting, has anybody any experience with this and the magnesium casing?
any and all experience appreciated.  Cheers

[Nathan S]

Yamaha magnesium brake plates and clutch covers will bead blast just fine.

Most epoxies are quite hard but not very tough, meaning that the bead-blaster will make fairly short work of them.

My gut feeling is that it will be fine.

[Rossvickicampbell]

I took the easy way out with my 83 and sent it to Geoff Morris who removed the old playdoh and repaired the case and pump area etc?

cheers

Rossco

[ideasman]

Hey Rosco, how do i get in contact will Geof Morris, and what sort of dollars would i be looking at.

[Hoony]

Geoff Morris is a forum member here look for "GMC" in the members section and shoot him a PM or Email. he also advertises in VMX Mag.

[vandy010]

sometimes the "poopy" glue stuff can be quite hard as Nathan said.
if you're able to use the die grinder first to remove the bulk of it, that'd make for less impact on the cases with the blaster.

[Slakewell]

I have repaired this type of cover before, You need to use alloy bur and get back to the parent material then you tig weld with Mag rods, you can build the case back to newish useing this meathod.

[Rossvickicampbell]

watch out for warping when welding though?

[smed]

I have the same problem with an 85 cr125,whilst searching for a good cover thats repairable cause mine is too far gone I came across a thread on thumpertalk,saying that the clutch cover from 89 will fit all cr250,s back to 85 & they are ally not mag,they may also have the 2 part cover for quick clutch access,I cannot verify if this is true or not but it might be worth looking into,also they may not look the same so if you were doing a correct resto no good but for a ride/race bike it would solve the problem for good,88 & 87 may also have the ally cover,once again you would have to research that,now if only the gods of 85 cr125 clutch covers would smile upon me i,d be a happy little vmx,er

[Slakewell]

watch out for warping when welding though?

Mag covers dont warp much as they need such low heat to weld 10 to 15 amp's in most cases, you just dont put much heat into them, still clamp them to a flat surface