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07 Phazer MTX Air Box Mod

Discussion in '4 Stroke Air Intake' started by UP bushman, Sep 26, 2011.

  1. Snowmixer

    Snowmixer Pro

    Snohomish, Washington
    2007 Phazer Mountain Lite
    2008 Phazer MTX
    2012 Arctic Cat M800 153
    I'm currently working on a project that will require some modifications of the airbox, and I feel that there are significant improvements possible by increasing the airflow, and especially if that air is colder. On my last sledding day of this season (June 1st), I had an unfortunate run-in with some trees as a result of the left-hand throttle being engaged unintentionally, resulting in a broken airbox and headlight. Okay, so it wasn't just accidentally engaged, it was pressed fully open and stayed that way until the sled and I came to rest in a stand of trees. Probably the scariest thing I've experienced on a sled so far!

    After we pulled the sled out and got it started, I was able to drive it back to the truck (only a mile or so), and it basically had no restrictions to the intake at all. The only part of the original 'intake' that was left was the two curved rubber 'horns' that direct air into the throttle body. I'm not sure exactly why, but the throttle response was INSANE! I don't think I had to press the throttle lever more than 1/8" for the whole drive back, and even the slightest press caused the sled to lurch forward. I was just relieved that it ran and I was able to limp it back to the trailer so I didn't mess around, but it surely felt like if I had just gone full-throttle for a second or two, the sled would have certainly pulled the skis off the ground, the torque just felt immense! As you can imagine, it was also pretty loud and sounded very burly, about like a 2-stroke motor with a loud can.

    So to sum it up, the throttle bodies had virtually no restrictions, and the two little hoses that run from the throttle body (one for each cylinder) to the air pressure sensor had pulled off. The sled didn't want to stay running at idle, but ran fine while driving. After I got home and re-attached the small hoses to the air pressure sensors, it idled fine again. At this point, I'm not sure if the extra throttle response and power was somehow just a result of those hoses being disconnected, or the fact that there were NO restrictions to the intake airflow. I'm leaning towards the unrestricted intake being the cause of the extra power, which has intrigued me and makes me wonder just how much power could be gained by a much more free-flowing intake.

    Since the headlight is broken (just the reflective back part where the bulbs mount) and I'm not too eager to spend $130 or so on another whole assembly, I've been considering making up some kind of velocity stack or intake tube arrangement that would be integrated with some projector beam headlights into one whole "intake/headlight" assembly. I'm curious if anyone else has had a similar experience with running their Phazer with no intake. Not that I suggest it, just wondering if anyone has had a similar experience with the extra throttle response and power.
  2. ATV PRO #11

    ATV PRO #11 Lifetime Member Lifetime VIP Member VIP Member

    Garson, MB, CANADA
    2014 Yamaha Phazer XTX
    Alot of good info here for guys like me getting ready to do a few mods!!

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