valve's question again

2 replies to this topic
  • iron_savior

Posted February 09, 2004 - 11:03 AM



i just wanted to find out a few things - what happens to a bike (xr650r)if the valves are on the tightish this
a bad thing ?

and i was also under the impression that valves loosen up
as time goes on, but according to other people they say they
actually get tighter.


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  • qadsan

Posted February 09, 2004 - 12:00 PM


It depends on how tightish we're talking. If you're talking a half thou or less as the difference, then the worst of the matter might be harder starting, less performance, etc, but the valve clearances on these bikes do have a tendancy to tighten up after a while. Remember, the valves are what lets the engine breath in and out based on the bump stick's profile. If it can't breath in a full mixture, then you can't expect the best from your bike. If it can't breath out a full breath, then perhaps some of the remaining exhaust gas that has already been burnt will contaminate the intake charge and combustion may not be as effective as it could have been. It just depends on how tight you're talking because too tight of valves can lead to burned valves or other expensive damage where as too loose could cause excess valve train noise, premature wear of the rocker adjuster screw or the valve stem itself. A good rule of thumb is that if you're not going for a perfect adjustment, then adjusting looser is less harmful than tighter, but it's best to get it right even if it means a little more tinkering time.

  • iron_savior

Posted February 09, 2004 - 07:04 PM


thanks quad - i learn something new everyday


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