Broken Crankcase Repair Options

[Black_Widow]

In the process of restoring an ATC 110 and I noticed the case has some pretty deep grooves from a loose chain. Oil leaks mildly out of the area behind the front sprocket at all times whether it's running or not. I'm sure I'm not the first one to run into this so my question is, whats the best repair option? :wondering I'm trying to stick with an epoxy type solution to avoid switching out the case or welding it. So..... JB Weld, Permatex, Loctite Metal, etc???? Any suggestions would be greatly appreciated.

[ironchop]

Ive used Loctite Magic Metal and JB Weld both to repair janky cases with chain rash.

Loctite Magic Metal sets up way faster than JB Weld and a little faster than JB Kwik Weld. I did feel like the JB products "stuck" better to what you applied them to before they dried. I like to rough up the surface with aggressive sandpaper. Blast it with brake cleaner to ensure no oils are left over on the part you want to epoxy. Put screen over any holes to keep the epoxy from falling through the hole. I`ve fixed a few beater bikes like this with great results before I learned to weld aluminum. Your results may vary.

[RubberSalt]

This is assuming the repairs to the mechanical part has been completed and only the cases need repaired.

As for repairs, welding is always going to be your best bet. Anything besides welding that uses heat, such as alumiweld, will probably hurt seals and what not, causing you to split the cases. In that event might as well use different cases. So at this point, we've got to omit anything of the such and go with epoxy.

Prep work is the most critical part here. The cleaner the surfaces, and the rougher the material, the better it will stick. Heavy sandpaper, or even a razor blade on the aluminum. Work around it, not in it).

Depending on the size of the hole:
If it's pin holes. Normal JB weld 2 part epoxy. I'd tilt the machine so oil isn't running out of the hole. Then hit it with break clean(or acetone/something to clean it all the oil and debris off), scrub it with a wire brush, more break clean. Make sure it's scuffed up for the Epoxy to grip onto. Mix up some epoxy, work it in to the groves that you made earlier, then smooth it over the hole. Leave the machine tilted for 24 hours to set up. Apply more epoxy to on top of the to give it more strength. You may need to roughen that up some.

If the holes are big enough that epoxy will drip into the motor. I'd roughen areas at least 1/2 inch around the hole. Apply epoxy to roughened part, then take mesh (window screen is example), the screen into the rough part. It'll cover the hole and give the next layer of epoxy something to grip onto. The Epoxy should be oozing through the screen around the hole. Apply epoxy on screen, lightly working in in. Once it's set up, make sure it's roughened, apply more epoxy.

If the hole is on a flat area, clean everything up very well. Get some flat aluminum that is thin and roughen the backside of it. Epoxy flat aluminum over hole.

[83ATC185]

Just my .02, this is great stuff, although not what you would call cost effective :)

http://www.3wheelerworld.com/showthread.php/179991-Belzona-1111

:beer

[Black_Widow]

To clarify, it is the area right behind the sprocket on the crankcase where the chain rubs. There are not any noticeable holes, just two lines gouged into the case about 2-3mm deep and likely a very small crack somewhere in the gouge. I've taken the left cover and sprocket off because I can't get in there at all to work, but one of the lines hit's right on the gasket seam with the left cover. I'd need to sand the epoxy on that edge once the repair is made to make it perfectly flat again... can you sand/or shape the globs of epoxy once you're done to form a decent gasket surface?

[Ghostv2]

To clarify, it is the area right behind the sprocket on the crankcase where the chain rubs. There are not any noticeable holes, just two lines gouged into the case about 2-3mm deep and likely a very small crack somewhere in the gouge. I've taken the left cover and sprocket off because I can't get in there at all to work, but one of the lines hit's right on the gasket seam with the left cover. I'd need to sand the epoxy on that edge once the repair is made to make it perfectly flat again... can you sand/or shape the globs of epoxy once you're done to form a decent gasket surface?

You can sand it, whether it seals is up to you. Without a picture I can't give exact advice. And without knowledge of your choice of epoxy. Like others stated JB weld isn't recommended for structural applications. It usually only has a 3-5 minute workable time period and some only has a temperature rating of about 250 degrees continuous. I'm not sure how hot a bottom end usually gets in the summer. You might have to get some more expensive epoxy if that doesn't work for you. And since JB weld isn't structural they recommend applying it 1" past the area you're trying to fix. So I'm not sure how filling in some scratches and sanding it flush again would hold up. Like I said, you might have to spend the money on the high quality stuff to get it to last. But since they are only small hairline cracks that weep, it might work for all I know.

[atc007]

I have had nothing but amazing things with OATEY epoxy. However,I am very intrigued by 185S' stuff he posted :) Whatever you use. CLEAN clean clean, Sand/prepare a surface it will adhere too. Final clean with ether/alcohol. Then your fancy epoxy ;). It will last a lifetime. I let it sit at least 24 hours with no oil in it. Then skimcoat it with threebond rubberized sealant. It is a lifetime fix for this area of a case..