V4 Broken powerhead mounting bolts

After heating and gentle hammering mounting bolts, I tried to remove the powerhead on my V4 Yamaha, and ended up with two of the six main mounting bolts broken. The two remaining bolts appear to be well coroded into the mid section. I would really appreciate some advise, has anyone been in the same situation? Is it possible the powerhead can be prised off with the bolt studz still in the mid section? I have heard of guys having to drill out the bolts through the side of the mid section..

Desparate for suggestions.

[cyrillefrenchy]

hello
it happened to me one time, i drilled the mid section along the studs and digg out the corrosion, and banged a little to break them loose.
hammer, pray bar and torche are the tools you need .
it was a pain in the house...
good luck
cyrillefrenchy

Thanks cyrillefrenchy,
The bolts are a small diameter and long, you did well to drill these out. Can you recall how far you drilled them down before you were able to get the power head off? I was hoping the bolts are corroded/seized at the bottom part.

[jb123]

you want to drill horizontally, in the mid section, near the top so powerhead so IT can be removed, then you can soak and beat the studs down/out afterwards.

you can also try heat first and it will take patience, just a propane or acetylene.

[cyrillefrenchy]

hello
you drill holes horizontally in the mid section, jb 123 explained better than me, do not try to drill out the stud, you won't .
the studs are 8mm - 5/16, try to drill a little bit bigger than the stud 10 mm -3/8 ant try to bang- digg out the white dust corrosion. take your time, that's the only way.
good luck
cyrillefrenchy

thanks every one, I ll let you know how we go.