crankcase rot repair

what does anyone recommend for repair? i have a set of case that besides the crankcase, are very nice. even all the original bearings are smooth and tight. non of the corrosion is completely through and is mostly contained to the bottom third. long ago i knew a former husky dealer that used devcon to repair his. anyone have suggestions on a good epoxy?

"Devcon" is the best if it can't be welded. I have used it for years to fix pump cavities on corroded magnesium water pumps side covers (CR500 Hondas) and it is a better product for this then JBweld is in my opinion.

sounds like a plan..thanks!

its all in the preparation. it must be spotless or it can peel off fairly quickly.

Both devcon and jb weld Have lots of products. http://www.devcon.com/products/products.cfm?brand=Devcon&cat=Metal Repair

I bought a similar sort of set of cases years ago and never used them. Researching it seems the airplane industry by 1930 was coming up with things. I have found more cases with problems at the rear insert than corroded insides. I feel the chances of the corrosion repair not holding up and questionable strength of the casting compared to new vs using the epoxy at the rear help me choose between the bent one the busted one and the rusted one so to speak. I would say two good condition swingarm inserts are worth about what the (just in general) whole corroded case set is.

I agree, the most important thing you must do is get it as clean as possible, bead blast the case and don't even touch the area you are repairing until the epoxy is applied. If it has powdery intergranular corrosion, die grind it out so it doesn't erupt again at a later date under the epoxy. This will cause the epoxy to start to peel eventually also.

Bead blast to get all corrosion out. Clean with auto metal prep solution then soap and water.
Apply your epoxy then sand to reshape area.
Brush on KBS rust seal paint in black. Then I sand and scuff. Recoat with second coat. Scuff/sand then spray over with Vht paint. Don't get to crazy with KBS paint. Just start with 1 thin coat to dry over night. As it digs into metal pores it has to let gas escape. Too heavy and you get bubbles.
KBS paint is just like what Husky factory used. It digs deep into pores of metal. Don't get on hands. Stuff has to be sand blasted off to remove. Just did about 6 cases and turned out great.

time to break out the die grinder. i agree about the swinger inserts, these ones were very nice..hard to lose for a bike that cost 265 or so!

If the Corrosion is Intergranular you'll need to go in with a die grinder. I've had a $8000.00 Zero Blast&Peen Cabinet for over 25 years that's big enough to put the bike in. It won't dig that corrosion out from deep in the layers in the metal like a die grinder will.

Hello.

One possebility is to solder it up with Zinc.
Have fixed a cracked gearbox on my old car with it and it still runs and yesterday I fixed a crack in my clutch cover.

Just an Idea for you guys.

Don't see a picture showing the level of damage you have but the best thing if possible even after I've suggested using Devcon myself is to Tig weld the offending section and repair it correctly. That of course may not be feasable in your case though, so lets see a picture of the corrosion damage you are speaking of ?
Ideally Aluminum should be repaired with aluminum!
Magnesium should be repaired with magnesium.

You may be correct however my luck with massive welding on these cases has been accompanied with clink clink sounds which must be cracking due to cooling/distortion. Chances are a heated argon chamber would be necessary. Even then magnesium to me anyway seems to not wet in and spread out very much. There are quite a bit of impurities in these cases and cast magnesium in general I do believe. It isn't like I didn't pre heat for an hour either. There is a whole family of low temp alloys I know little about besides eutectic seems to be or was a major player.

Will it really corrode more if the engine is coated in two cycle oil. I have plenty of cases where the black coating is gone from a portion of the insides near the crank on one side but no corrosion. I kind of figured the corrosion was caused by race gas and mystrey chemicals in it, or storage of the bike in a high condensation environment.

Who knows whether it needs massive welding or not fran...k ! Lets see a picture of the damage "justintendo". Too much conjecture here not even knowing what we are talking about.

Thanks for the pictures justintendo, That damage being in the crankcase area is not good. It looks like the case mating surfaces are about gone? This is going to be a decision you will have to make whether to try and save it or not.

it would be a no brainer for me if the cases looked like crap, lol! i am thinking of pressing the bearings out along with swingarm pivots and being happy happy i got a good crank, rod, and stock bore jug..i have bedded rifles with success so i know i can fix the cases but i would probably worry about it..noy to mention the labor time fixing it..

these pics are with everything a flathead screwdriver would remove. so everything there is at least half solid. these cases had definitely not been split before

Those look good to me. Remember, the inner area for the 250 cases dont have to seal, the outer area will make the case area air tight, so you are better off than if it was a open class crank.

If the inner surface isn't required to seal than I would just beadblast it all clean and as long as the pitting doesn't go any deeper or isn't all the way through I wouldn't use any epoxy whatsoever. Knock out the seals an bearings replace them and stay away from the heat of any welding unless absolutely needed. I now see the original paint still on that edge and on the inside. Re apply the proper paint case coating if desired. Prep well like dartyppyt suggests.

A trick I learned years ago is remove the Case locater dowel from each end of the cases 1 at a time and use some valve lapping compound (Clover compound) on the mating surface and rub the cases together with a wiping motion like you are wiping your hands. This will lap the case mating surfaces if done properly. Then install the first Dowel and remove the opposite end dowel and do the same thing the other way. Open up the cases so you can look at the mating surfaces. If it all looks good, than go ahead and run them.

you lap cases against each other i use a granite slab i have a good size chunk of tempered plate glass too

The intent of the massive welding part of the post you quoted was to indicate I have had success welding up limited amounts (read an inch or so edege or end) on these cases but there is a downside involved with welding, I didn't even go into the distortion aspect. It had nothing to do with this particular set of cases.