peterl95124
Well-Known Member
- Joined
- Feb 22, 2020
- Messages
- 509
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I have a Magnum (chinese made from japanese OS molds) 120 four stroke that needs some work,
I thought being a model engine builder this should not be too hard,
only to become extremely disappointed with the Magnum internals once I got it apart,
the valves need to be replaced because they're steel rather than stainless and in a methanol
engine that doesn't last, mine are so rusty the stems looks like they are about to break
the bearings need to be replaced because they're steel rather than stainless and in a methanol
engine that doesn't last, mine are so rusty they don't turn smooth even after cleaning and oiling
I can make my own replacement valves from stainless,
and I can buy replacement bearings in stainless,
but firstly I can't get the bottom camshaft bearing out, its at the bottom of a blind hole,
and its in there tight, no amount of heat and whacking it on a wood block will get it out.
I also read about hydraulically forcing it out by pouring molten wax
down the bearing ID and then pounding a close fit rod down the hole, but my bearings aren't
sealed so the wax, after cooling and hardening, just oozes out past the retainer.
design wise the camshaft bore needs to be open at both ends and capped at both ends so
the bearings can be removed, but that's 20/20 hindsight and doesn't apply to an already built engine
has anyone else solved this problem, if so how ?
TIA,
Peter A Lawrence.
I thought being a model engine builder this should not be too hard,
only to become extremely disappointed with the Magnum internals once I got it apart,
the valves need to be replaced because they're steel rather than stainless and in a methanol
engine that doesn't last, mine are so rusty the stems looks like they are about to break
the bearings need to be replaced because they're steel rather than stainless and in a methanol
engine that doesn't last, mine are so rusty they don't turn smooth even after cleaning and oiling
I can make my own replacement valves from stainless,
and I can buy replacement bearings in stainless,
but firstly I can't get the bottom camshaft bearing out, its at the bottom of a blind hole,
and its in there tight, no amount of heat and whacking it on a wood block will get it out.
I also read about hydraulically forcing it out by pouring molten wax
down the bearing ID and then pounding a close fit rod down the hole, but my bearings aren't
sealed so the wax, after cooling and hardening, just oozes out past the retainer.
design wise the camshaft bore needs to be open at both ends and capped at both ends so
the bearings can be removed, but that's 20/20 hindsight and doesn't apply to an already built engine
has anyone else solved this problem, if so how ?
TIA,
Peter A Lawrence.