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Thread: Wide Inlet margin

  1. #1

    Wide Inlet margin

    Hi folks i noticed that my inlet valve extend about 1 mm. from the face of the valve and i was wondering if i should grind the valve down so the diameter is no bigger than the actual face area in order to improve airflow at low lift.
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  2. #2
    Senior Member MadMax's Avatar
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    No, if it's as it came from the factory, leave well alone, if you've modified the valve seat, please explain?

  3. #3
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    Sinking the valve moves the valve seat closer to the SSR and losses air flow as a result.

  4. #4
    Quote Originally Posted by MadMax View Post
    No, if it's as it came from the factory, leave well alone, if you've modified the valve seat, please explain?


    I think this what happened, its deformed. like this ;
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    Last edited by rex; 11-13-2017 at 07:54 AM.

  5. #5
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    I'd say that valve is worn out beyond repair.

  6. #6
    Senior Member MadMax's Avatar
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    I'm curious as to what the valve seat in the head looks like? If it has worn/eroded as badly as the valve face then a new one will never sit correctly and it'll need re-cut (assuming there is enough metal left).

    That looks like the result of typical valve seat recession due to unleaded fuel which shouldn't happen (I won't say can't), more likely due to incorrect valve clearance, a badly worn valve guide or overheating due to a weak mixture?

    I've never had to have valves re-cut on any Japanese bike engine (just a 3.0 Capri a long time ago) so I'm no expert on the thickness of hardened seats and how much can be safely machined out of them to recover the correct profile, hopefully one of our resident expert engine builders will be along soon to advise....

    Max
    Last edited by MadMax; 11-13-2017 at 09:27 AM.

  7. #7
    Quote Originally Posted by pcnsd View Post
    Sinking the valve moves the valve seat closer to the SSR and losses air flow as a result.
    +1 to what Paul said.

    Also what MadMax said - something is wonky if it did that.

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