| Also known as | R1620.040 |
| Listed in parts books | Not catalogued by year yet |
PISTONS TRI 500 8.5:1 -66
Oversize (.040) piston for the Triumph 500 twin, listed at 8.5:1 compression, for engines through 1966.
This is a piston listed for the Triumph 500 twin, called out at an 8.5:1 compression ratio and tied to model years up through 1966 in our records. The R1620/040 number is a supplier code rather than a Triumph factory part number, and the .040 designation tells you this is an oversize piston for a rebore, not a standard-bore replacement.
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Beyond the compression ratio and the oversize marking, our records on this one are brief. If you're rebuilding a 500 twin top end, get your barrels measured before ordering so the .040 over size actually matches what your machinist cut.
Call the shop if you want us to confirm this against your specific engine before you order — pistons are one part where guessing at bore size costs you twice.
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