QuestionI have 2 bikes, in both of them, engine casings have cracked. After one was welded, it cracked within 1/2hr.. Can I put another engine in from another year or size of (cc)? What is the best thing to do in your opinion?
AnswerHi George,
A new case is always the best but many people
have had luck repairing engine cases
with 24 hour cure JB Weld epoxy or
Loctite QuickMetal putty epoxy.
The scenario goes like this:
Clean all the oil away around the crack
with brake cleaner.
If you can, grind a V into the cracked area
about half way down through the case.
Use either the 2 part putty or long cure JB Weld epoxy only.
Mix and apply the two part epoxy and then warm the engine case
with a hair dryer or low oven heat to cure the weld a bit.
If you rough up the area a bit the epoxy will stick better.
It has to be very clean and use only the long cure epoxy
letting it fully cure before use. Heating the case
a bit can reduce the cure time as well.
If done carefully these epoxy welds can last
a very long time. Success may vary due
to the area of the crack. If stresses are
high it may tend to break.
You can achieve an almost invisible repair with
some practice. Sometimes this is the only
recourse on an older bike and it works better
than most metal welds if done carefully.
If the hole is large you can use a plastic mesh
to make a backing or even screw on a support
where there is room.
I have seen a clean epoxy weld last ten years
so it is a good alternative to a new
or used case.
You may want to check out a more expensive
but effective product like this:
http://www.markingpendepot.com/browseproducts/Devcon-Aluminum-Putty-(F).HTML
Good luck!
Wayne S.
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