Was fitting some new rearsets to my Aprilia RSVR which allowed me to junk a couple of brackets that were attached using crankcase bolts. Whilst doing
so I noticed what looked like a hairline-crack in the crankcase. I put a little pressure on the bolt... and sure enough - it spun reasonably freely.
Someone in the past has obviously tightened the bolt too much and stripped the threads. 
And possibly (probably) stressed that area of the
crankcase causing the crack! 
I've only ridden the bike a couple of hundred easy miles since getting it due to the time of year it arrived, and I've not seen any sign of
a leak.
So what to do!?
Leave it and top-up with oil if it starts to weep?
Notch a groove along its line and seal with epoxy or chemical metal?
That won't leak leave it be. If you really want it fixes the only proper way is to strip it tig it and reassemble.
Cheers Ash. I'm also a bit concerned that the bolt isn't really exerting any pressure in the area. Mind you, it's one of the higher
crankcase bolts and the ones either side are good.
[Edited on 11/4/14 by scootz]
Blank it from your mind and ignore
I have seen that exact type of crack caused Byzantine hydraulic pressure caused by oil trapped in a blind hole when tightening the bolt.
[Edited on 11/4/14 by britishtrident]
quote:
Originally posted by britishtrident
I have seen that exact type of crack caused by hydraulic pressure caused by oil trapped in a blind hole when tightening the bolt.
quote:
Originally posted by mark chandler
Blank it from your mind and ignore
If you want to hide it and provide a modicum of seal I'd use use some silver/ali epoxy bodyfiller - search Silver Hook Big Boy body filler.
Whilst I'd agree that it probably won't spread or weep it will catch your eye less.
May be best to wash out the crack with meths or similar first.
I used a similar method on the plastic timing chest case on the hairdressers to pretty good effect.
HTH and safe riding.
Cheers, Pewe10 
Quote "......Byzantine hydraulic pressure......"?????
What a remarkable description!! So how much would that be - in old-fashioned psi?
[Edited on 11/4/14 by Dick Axtell]
Cheers all.
It would take a very brave man to wash Scootz's crack out with meths.
[Edited on 11/4/14 by CRAIGR]
It'd be worth it for the lucky chap though as he'd get a nice cuddle afterwards! 
Hahaha
Sod that. Next time keep your crack to yourself!
If the bolt hasn't come out it's tight enough.
Another solution would be to screw a stud in with a bit of sealant on the threads and then fit a nut. You can make sure the stud takes advantage of whatever threads are left in the hole and if you use a OEM typre flanged-nut, it won't look out of place.
Hi
From the look of it it should be fine , the crack does not look the be
in the oily part of the crankcase.
If you'r worried about the bolt coming out use threadlock on it.
Whatever you choose , good luck.
Thanks all.