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Assessing cam chain...

Discussion in 'Bling and Appearance' started by mattb, Aug 3, 2007.

  1. How do you assess if a cam chain needs replacing?

    (I'm not having a particular problem, am just generally interested.)

    Obviously, if you know when it was last replaced, you can just plan when to replace it next, eg in 25 - 30,000km from the previous one. But if you get a second hand bike you might lack this information, and furthermore I've had to replace a couple of bikes' speedos - you can't necessarily rely on the odometer to tell you much.

    But I take it your cam chain can be worn out even if there's slack still left to take up with the tensioner? (-just as a drive chain can.) And if so, what then - is there a way aside from removing the top of the engine?

  2. General rule of thumb, [ not applicable to all bikes ] if yah can hear it, replace it. But yes to check it properly you have to remove the top cover.

    Then you look for things like wear on the followers, general slackness and side movement of the chain to cam gears etc etc.

    Some bikes you have to remove and measure the free length, but if you've gone that far i'd be replacing it anyway :p

    Some manuals even give you measuring tables for between X amount of links [ service limit ]
  3. I generally take a rocker cover off an engine, anything so I can see the chain. Then turn crank bolt back and forth. If I find more than about 10mm end of spanner movement before the cams start moving, I see if I can adjust a tensioner, if not, new chain.
    My measurement is not endorsed by any manufacturer, but it serves me well! If you have enough slack to make noise when moved in this way, best to get a chain stat!

    Regards, Andrew.
  4. Sometimes you can see wear marks by the chains rivets. If this is excessive, replace it.
    Some manufacturers give a chain length (links per inch) That makes it a bit easier but if in doubt, chain it. It's a small price to pay as if it snaps, you can total the engine.
  5. As a guide, you shouldn't be looking at it with less than 80,000km anyway.