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FJR Motorcycle Forums
Technical & Mechanical Problems
First gen timing chain questions.
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<blockquote data-quote="Fred W" data-source="post: 1284893" data-attributes="member: 3828"><p>Wow. 7600 miles is barely broken in. But you probably already knew that when you bought it.</p><p></p><p>The original FJR timing chain tensioners, which your original '03 would have in it, had a wimpy spring in them. and since there is no ratcheting mechanism in the tensioner design, there was a possibility of the chain compressing the tensioner and creating enough slack for the chain to skip a few teeth on the crankshaft drive sprocket. Since it is an interference engine, skipping a few teeth results in piston valve collision that bends the valves at best, and can damage piston crowns at worst. The rate of occurrence is not huge, but the unfortunate consequences are, so many owners will replace the old tensioner with one of the newer design. The part number will automatically change up to the new one if you order the part from Yamaha. When you have the part in hand, the updated part will have either a blue, or more lately green, paint dot on the body of the tensioner.</p><p></p><p>The job is a bit tricky (tight spaces) and you do want to open the timing cover and restrain the chain while swapping the tensioners, so browse around and find one of the accounts of the job here on the forum that gives you the details before you begin.</p><p></p><p>edit - and this time Professor ionbeam beat me in the typing. <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite2" alt=";)" title="Wink ;)" loading="lazy" data-shortname=";)" /></p></blockquote><p></p>
[QUOTE="Fred W, post: 1284893, member: 3828"] Wow. 7600 miles is barely broken in. But you probably already knew that when you bought it. The original FJR timing chain tensioners, which your original '03 would have in it, had a wimpy spring in them. and since there is no ratcheting mechanism in the tensioner design, there was a possibility of the chain compressing the tensioner and creating enough slack for the chain to skip a few teeth on the crankshaft drive sprocket. Since it is an interference engine, skipping a few teeth results in piston valve collision that bends the valves at best, and can damage piston crowns at worst. The rate of occurrence is not huge, but the unfortunate consequences are, so many owners will replace the old tensioner with one of the newer design. The part number will automatically change up to the new one if you order the part from Yamaha. When you have the part in hand, the updated part will have either a blue, or more lately green, paint dot on the body of the tensioner. The job is a bit tricky (tight spaces) and you do want to open the timing cover and restrain the chain while swapping the tensioners, so browse around and find one of the accounts of the job here on the forum that gives you the details before you begin. edit - and this time Professor ionbeam beat me in the typing. ;) [/QUOTE]
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FJR Motorcycle Forums
Technical & Mechanical Problems
First gen timing chain questions.
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