Crankcase crack on an 86 Spree

[KeithMcFly]

Would a cracked crankcase affect the performance on a motor? The crack is small but the cost of a new crackcase is on the higher side. Thanks for your advice guys.

[kpa2004]

Got a Picture? Maybe stop-drill it so it doesnt migrate.

[Wheelman-111]

Greetings:

A lot depends on where the crack lies on the crankcase. If it's anywhere near the crankshaft's cavity it should not be run like that, because it will produce the equivalent of a vacuum leak. That will cause your engine to burn a very lean mixture, overheat and fail very quickly.

If the crankcase is cracked farther back - in the section that serves as a swingarm - nothing bad will happen to your engine. Only the wheel can fall off, and what's so bad about that?

I have seen posts and eBay items where ham-fisted "Mechanics" have managed to crack the alternator housiing. Except for water penetration, that shouldn't cause any issues. Perhaps the water can be repelled by silicone sealant once the build is assembled.