one of my head bolts ( connected to the lower motor) cracked when i was tightening the nut onto it.
what do i do to fix it?

Pull it and the rest of the bolst out and replace with new ones. better yet replace with studs and nuts.

Cheers

Aaron

_________________

If it still has those POS bolts (used on Oz 1098s mainly) they are 30+ years old, fatigued and prone to breakage.. I'll never ever use them again.
As Aaron says, studs & nuts are better. Either use the later flanged nuts, or put proper thick Mini head washers under. Not the crap Chinese soft thin flat washers every hardware has now..

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

can they just be pulled out? it is stuck in there quite hard

I take it the head is off?
Various methods to get the remains out (in order of severity) after you spray some WD40 at it:
1. grab it with vicegrip pliers.
2. tap it anticlockwise (gently!) with a hammer and centre punch.
3.drill a hole in centre of it and use an Ezi-out.
4. drill a 3/16" hole exactly in centre of of it. Nice and square too. Drill that out to 5/16", again nice and square. Carefully screw a 3/8" UNC taper or intermediate tap in there and it will clean out the thread.

If #1 & 2 don't work and you are aghast at trying the rest, take it to someone who has experience... it's easy to strip the thread in the hole if you are not careful.

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.