If you crack the case, you're going to have to reseal the entire 
 thing.  the sealant that's there is the whole way around and a very 
 thin layer of the stuff.  Try just tightening them thar existing 
 bolts, maybe you'll get lucky. Also, are you sure it isn't leaking 
 from somewhere else?  A light seep from the countershaft oil seal 
 rolls down to there, as well as over-oiling the chain.  Opinions 
 only, you might have a cracked case and tightening won't matter.
 millerized
 
 --- In 
DSN_klr650@yahoogroups.com, "rfcullison" 
  wrote:
 
 > I have a very slow oil leak from the lower back of the crankcase, 
 > between the second and third crankcase bolts on the bottom. Just 
 > noticed it after comming back from the PA ride.  There aren't any 
 > cracks that I can see, it just seems to be weeping at the joint.  
 > It's not leaking a lot, the oil level is not noticibly down over 
  
the 
 
 > last few days, just enough to spot the driveway and be annoying.  
  
On 
 
 > the other hand, it does make me a bit nostalgic for the several 
  
old 
 
 > British singles I owned back in the 70's.  Question to the group.  
  
Is 
 
 > there any way to fix this without pulling the engine and splitting 
 > the cases?  From the parts diagram there doesn't seem to be a 
  
gasket 
 
 > there, I assume some sort of liquid gasket material is used.  I 
  
was 
 
 > thinking it might be possible to drain the oil, loosen up all the 
 > crankcase bolts I could find and possibly get enough of a gap to 
  
get 
 
 > some gasket compound up in the joint.  I can live with this leak 
  
for 
 
 > a while, so don't want to cause more problems than I solve.
 > 
 > Thanks
 > 
 > Richard