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  1. #1
    SJL Custom's Avatar
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    Oversized Valves

    Quick question. Thinking of going with oversized valves (32mm Exhaust, 39mm Intake) and wanted to know if they require any additional machining to fit. Do the piston reliefs have to be enlarged as well so that the valves dont make contact with the pistons, or will they clear no problem, untouched?


  2. #2
    Eastside Powersports Slow 91's Avatar
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    +2 mm exhaust valves *should* work in stock reliefs. Intakes will need to clearanced. I dont need a point at all to run larger intake valves, they are big from the factory. Just run big exhaust valves. The seats need to be cut for larger valves as well.

  3. #3
    SJL Custom's Avatar
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    Just the guy i was looking to answer this. So +2mm on the exhaust is ok but +1mm on the intake side will need to be clearanced?

  4. #4
    SJL Custom's Avatar
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    Anyone else have any insight into this?

  5. #5
    BLACK MAGIC HEADERS hydrojunkie's Avatar
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    yes at high revs be prepared to loose your valve seats. been there done that.

  6. #6
    SJL Custom's Avatar
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    lose the valve seats on the oversized or stock sized?

  7. #7
    BLACK MAGIC HEADERS hydrojunkie's Avatar
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    when you cut into the stock valve seats, there really isnt alot of material there to start with. now once you cut the seats to accomodate the larger valve you risk the seat coming loose from its pocket. it has happened to me and it sucks ass. i will never go down that road again. EVER.

  8. #8
    SJL Custom's Avatar
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    so what do you suggest, staying with factory sized valves?

  9. #9
    BLACK MAGIC HEADERS hydrojunkie's Avatar
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    yes all the way.

  10. #10
    Don't know why u would want to put bigger valves when there are alot of guys running over 400hp with stock valves.

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