Causes of HD Twin Cam Engine Noise

by Jamie Rankin
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A twin cam engine has two camshafts — usually double overhead cams. The camshaft is the part of a car or motorcycle engine that operates the inlet and exhaust valves. A vehicle with a twin cam engine has one camshaft controlling the engine’s inlet valve and a separate one operating the exhaust valve. Harley-Davidson (HD) motorcycles come equipped with these types of engines, and sometimes, riders report engine noise. These sounds can result from several possible causes.

Worn Cam Chain Tensioner

A cam tensioner, as its name implies, adjusts the tension on the engine’s cam chain. When the tensioner requires replacement, the cam chain can become slack and begin to make noise. Chain tensioner tools on the market will allow you to adjust your Harley-Davidson cam chain manually. If the noise continues, however, it may mean that the cam chain itself has become worn and requires replacement.

Worn Cam Sprocket

If you need to replace your cam chain, you should probably replace your cam sprocket as well. Because the chain rotates this part, which is connected to the end of the camshaft, a worn, loose or malfunctioning chain will not rotate the sprocket correctly. By the time you notice the problem and replace the chain, the cam sprocket will most have become worn out as well. Instead of sitting securely in place, a worn sprocket may jump, causing further engine noise.

Cam Bearing Failures

The Harley-Davidson Twin Cam TC88 engine replaced the company’s Evolution engine and, for the most part, improved on it. However, some riders found the TC88 to have a problem with its cam-support bearings. The problems occurred in only a small percentage of the bikes, and the company quickly identified and corrected the issue. Still, if your twin cam engine is noisy and you drive a Harley with this engine style, check your cam bearings just to be safe.

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