| Also known as | I204F |
| Diagram | Fig. 5 — GEAR CLUSTER · ref 75 |
| Listed in parts books | 1968–1971 |
BUSH,KICK START B25/50
Kickstart bush for the B25/50, also listed under the older I204F part number.
57-2642 is a kickstart bush, the part that lines the bore where the kickstart shaft or quadrant rides. The canonical description ties it to the B25/50 family, which tells us this is a BSA-model application even though it's filed under a Triumph-style part number — that's common on unit singles where BSA and Triumph shared components across the line. It's also known under the older I204F designation.
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A kickstart bush like this is a wear item. It takes the friction load every time the kickstart shaft rotates against its housing, and over years of use the bore opens up, the shaft starts to slop around, and the kickstart action gets sloppy or the shaft can bind. Swapping in a fresh bush restores that fit and keeps the shaft running true against its bore.
We don't have much more on file for this one beyond the basic description and the old part number cross-reference. If you're not sure whether this is the right bush for what you're working on, give us a call with your parts book number and we'll confirm before you order.
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