| Also known as | CH001 |
| Listed in parts books | Not catalogued by year yet |
HEAD GASKET 8 BOLT 650/500 Pre-Unit - .048 thick with oil drain holes (Internal Drains)
Head gasket for 8-bolt pre-unit Triumph 650/500 twins, .048 in. thick, with internal oil drain holes.
This is the head gasket for the pre-unit Triumph 650 and 500 twins, the 8-bolt cylinder head pattern. It seats between the cylinder barrel and head, sealing combustion pressure and keeping oil routed through the internal drain passages back where it belongs. It's cut to .048 in. thick and made for the internal-drain head configuration, so the oil return holes are built into the gasket itself rather than relying on external oil lines.
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This older part number also shows up in some records under CH001, which is the same physical gasket under a different catalog code. If you're rebuilding a pre-unit top end, this is a one-time-use item — plan on a fresh one any time the head comes off.
We don't have extensive fitment notes beyond the 8-bolt pre-unit 650/500 pattern itself, so if you're not sure whether your engine uses the internal-drain head, give us a call before you order.
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