| Also known as | E4157 |
| Diagram | Fig. 11 — ENGINE FITTINGS AND EXHAUST SYSTEM · ref 32 |
| Subsystem | exhaust |
| Listed in parts books | 1966–1970 |
Left silencer (muffler)
Left-side silencer (muffler) for the Triumph twin exhaust system, factory number 70-4157, later superseded by 71-2017W.
70-4157 is the left-side silencer, what most folks these days just call the left muffler, off the exhaust system on unit-construction Triumph twins. It shows up in the catalog under the engine fittings and exhaust system figures across appearances running from 1966 through 1970, and it's also listed under the older E4157 alias if you're working from an earlier parts book.
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This part carries the tone away from the head pipe and out the back of the machine on the left side, and it's a factory number, not an aftermarket repro description. The catalog record shows this number was superseded down the line by 71-2017W, so if your parts book lists that number instead, you're looking at the same silencer position updated to a later part.
We don't have finer detail on baffle type, bore, or exact length in our records for this one, so if you're trying to match an original look or a specific year, bring in what you've got or give us a call and we'll work through fitment before you order.
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