| Also known as | E4322 |
| Diagram | Fig. 2 — CRANKCASE · ref 23 |
| Subsystem | engine bottom |
| Listed in parts books | 1964–1968 |
Right main bearing
Timing-side main bearing bush for the crankcase on Triumph's smaller unit twins.
70-4322 is the timing-side main bearing bush for Triumph's smaller unit-construction twins. It sits in the crankcase and supports the timing-side end of the crankshaft, letting the crank spin true while also playing a part in getting oil where it needs to go on that side of the engine. You'll find it listed under the CRANKCASE section of the parts book, and it also shows up under the earlier E4322 number if you're working from an older catalog.
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This bush takes the wear that comes with holding the timing-side journal steady, and because oil has to pass through it on its way to the rest of the bottom end, a worn one can starve the big-end bearings before you even notice a problem elsewhere. If you're doing a bottom-end rebuild on one of these smaller twins, it's worth checking this bush for wear and clearance rather than assuming it's fine because the rest of the engine looks good.
Our catalog references for this part run from the mid-to-late 1960s, so if your parts book shows a different range for your specific bike, give us a call and we'll sort out what you actually need.
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