KDXRIDER.NET

There's a small crack in the case of my kid's KX85. It's near the countershaft, seeps a very small amount of oil, and I'd rather not split the case to fix it. I'd leave it alone, but my wife is already pissed about all the dirtbikes in the garage, if they wet their pants, it's even worse. The guy that I bought it from tried dabbing some JB weld on it, which worked for a while. I was thinking that if I could get a vacuum to build in the case, I could get a small amount of adhesive to draw into the crack and seal better. Anybody try this? Another thought was those aluminum welding rods they advertise at the home shows that only need a low temperature torch. Think that would work?

Take the oil out. Lay the bike on its side and take off whats needed to get a good work at the crack. Take carb cleaner and a wire brush and clean the crap out of the area. Buy JB Weld-Mix & apply. Let dry overnight and wala. You just saved you self alot of Do, Ra, MEESSSS

The area has to be very, very, very clean & DRY. If not the JB Weld will not secure to the metal properly. And do not DAB, apply a good coat of JB WELD

As above but using contact cleaner (unless its the same thing as carb cleaner). I would give it a real good blow with compressed air into and around the crack. I would then scuff the surrounding area a little so the JB sticks better too. Not knocking your method GH just a few extra steps 'I' would take.

I forgot to mention the scruffing, I put a round copper brush on my Makita Drill and used that the clean & scruff. The contact Cleaner, electrical cleaner, brake cleaner, carb cleaner all work the same. Use what ya got.
A CLEAN CRACK IS A HAPPY CRACK
After the JB Hardens, use the copper brush to shape the weld (Go lightly) and then apply your favorite paint

thank guys, I'll give the JB weld a shot. I bet the case wasn't cleaned properly before.

Another alternative that I like WAY more than JB weld is Marine Tex. If you can find it, it's far superior to JB weld in holding strength. Use the same methods as above for prep. I've used Marine Tex to fix cracks in transmissions on my old Isuzu pickup truck. :)

I also have used marine tex. It's made specificly for aluminum I think. It's used to patch holes in aluminum hulls anyways. I like your idea on pulling a vacuum on the case and sucking in some of what-ever you use. Is the crack that big?

YOu could probably rig up some way to pull a vacuum from the oil plug opening. Good luck and let us know how it works.

My 86 KDX had a small crack in the case from hitting a rock. I got my dremil tool and put a VERY SMALL groove along the length of the crack. The depth of the groove wasn't more than .010 deep. I filled it with a product called Metal Set. The metal set is an epoxy impregnated with aluminum particles. The fix worked for two years and was still holding when I sold the bike. The Marine Tex sounds like the same type product.

I was gonna mention the groove trick but wans't sure of the size of the crack or accessability. I also thought about the vacum answer but forgot to reply. I was gonna say you would need a fair amount of 'suck' to draw anything through a fine crack, seals etc mightn't like that much 'suck' either. Sounds like you got it sorted anyway....