505 SX +1 valve Questions
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  1. #1
    Junior Member Rookie
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    Nov 2019
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    Minnesota
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    505 SX +1 valve Questions

    Who has been running +1 valves and where did you get them? What springs are you running with the +1? I'm new to the KTM world and I'm finding these unicorns are kinda hard to find parts for. Any info is appreciated.

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  2. #2
    Senior Member KTMATVHQ Guru
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    Dec 2008
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    I've never heard of anyone running +1mm valves in a SX head. It is a more popular mod on the XC heads, but that's a completely different engine family. I don't know if it's because there's no room to go bigger in the head, or if the stock size valves are already big enough to flow the volume of air that the rest of the intake can deliver. Members on here have hit a strong 65hp with cam(s), good port work, piston, open intake, 43mm carb bore, exhaust, and ignition. Also, the factory Ti valves are produced by DelWest and are really high quality.
    Mine:
    2017 Husky FX 450
    2009 505 SX
    2008 525 XC-modded for mx (currently 450 cylinder)
    Dad's:
    2009 450 SX
    2008 540 XC

  3. #3
    Junior Member Rookie
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    Minnesota
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    Quote Originally Posted by quad97 View Post
    I've never heard of anyone running +1mm valves in a SX head. It is a more popular mod on the XC heads, but that's a completely different engine family. I don't know if it's because there's no room to go bigger in the head, or if the stock size valves are already big enough to flow the volume of air that the rest of the intake can deliver. Members on here have hit a strong 65hp with cam(s), good port work, piston, open intake, 43mm carb bore, exhaust, and ignition. Also, the factory Ti valves are produced by DelWest and are really high quality.
    That's what I figured when I couldn't find any off-the-shelf +1's. I'm from the Honda/Yamaha side so everything is +1 or even +2 on big bore/stroker engines. Already have a Dasa Exhaust, SXF ignition (can't find a Vortex), & 43.5mm FCR. I'm just trying to decide on compression ratio, cam spec, and valve/spring combo.


 

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