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Exhaust sound gets quiet on the way. Valves too tight?

Discussion in 'CARC' started by Kuzya, Mar 14, 2017.

  1. Kuzya

    Kuzya Tuned and Synch'ed

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    1200 sport 2V with Mistral silencer.
    In the middle of the road, suddenly, the exhaust sound almost disappears, gets very silent. The ride feels smooth. Usually happens on hot days, irregularly.
    Can it be because of too tight valve clearance and exhaust valves not closing properly, so smoothening the pressure wave? Or would I have felt the not closed valves as a total power loss? Cause the bike is rolling kind of ok, just scaringly quiet.
     
  2. GT-Rx®

    GT-Rx® Administrator Staff Member GT di Razza Pura

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    This is a physics question, not a running question. Could be a dozen things. If the bike is in a decent/recent state of tune, and the fueling is still stock, I would highly recommend a fuel map revision that I can be of help with.
     
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  3. kiwi dave

    kiwi dave GT Reference

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    You're not by chance climbing up to a reasonable altitude and then returning down to sea level by any chance?

    My bike gets very quiet in these circumstances (and then my ears hurt!).
     
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  4. Oz1200Guzzi

    Oz1200Guzzi High Miler

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    Going deaf - try earplugs
     
  5. Kuzya

    Kuzya Tuned and Synch'ed

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    Thanks Todd! I'm a happy owner of the O2 tuning box of yours, runs much cooler sinse than, reacher than stock, and so much smoother. Only the silencer is non-stock, and snorkeloctomy with stock air filter. Does not seem to be overlean. Will look at spark plugs state and come back to your offer.
     
  6. Kuzya

    Kuzya Tuned and Synch'ed

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    Also interesting sympthom. But not my case...
     
  7. Kuzya

    Kuzya Tuned and Synch'ed

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    After this happened to my other bike, w800, it proved that the small hill climb is the reason. Interestingly, the other street sounds appeared ok through the full face helmet, no sign of pressure change deafness, which is usually noticeable on all the sound picture.
    Good thing is - bike okay, me - learned something new. Amazing how the jokes on possible deafness looked strange above at the first glance....
     
  8. John Warner

    John Warner Cruisin' Guzzisti GT Contributor

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    Unlike many Engines, the Valve Clearances on the 1200 CARCs increase as the Engine temp increases.
     

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