We will be creating a YouTube video in the near future showing cracked motorcycle crankcase repairs.
We come across this enquiry so often, we decided to create a web page to help people solve this problem.
Chains breaking and smashing the crankcase across the engine casings.
Unfortunately, this can’t be welded without splitting the crankcase because the gasket will get destroyed from the welding heat which is 660 degrees C.
A number of my customers have experienced great success following these repair method instructions.
The JB weld, or epoxy repair method does work. But the secret to success is in the preparation, which is vital.
If the preparation is not done methodically, no epoxy on this planet will work.
Cracked motorcycle crankcase repairs
Scrape out all the old JB weld material, if a previous attempt has been made.
Get some degreaser spray and clean out the area to be repaired, making sure all surfaces are perfectly cleaned out. There must be no traces of oil or grease at all.
Oil is used as a release agent when casting moulds. So there must be no traces of any oil whatsoever.
That’s just the start of the preparation.
Then find yourself some abrasive tools like a pointed wire brush to fit on the end of a drilling machine. The courser the wire brush the better. Or, even better still, small sanding discs to fit in your drilling machine.
You must also use very course sand paper say 40-60 grit and get in using a stew driver to push and shove over the surfaces.
You need to get the aluminium casing as rough as possible. Not smooth. The epoxy will stick to a rough surface, not smooth.
Once you have made sure every part of the surface is sanded down, use a 4mm drill bit in your drilling machine and run over the surfaces using the side of the drill bit to scrape over the aluminium surfaces. Cleaning and roughening it all up.
Next, get yourself some thinners.
Use a small paint brush and clean all the surfaces making 100% sure there are no traces of any oil.
That’s it. Now apply JB weld around the area to be sealed off.
This repair applies to any casing crack repair. Not only as described. This will work on hard plastic, steel, cast iron….. too. As long as there is no flexing
All the best.
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