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  • vacuum at idle

    Brent, I know it's supposed to be 20in. Sorry if I made it sound like you were wrong. The only thing I have never checked is valve timing. But if valve timing is off that bad wouldn't I have lower compression (175psi)? 39 MPG. It seems to run great. I say "seems" because I have never had it on a dyno or road with another 11.
    79 F full cruiser, stainless brake lines, spade fuses, Accel coils, modded air box w/larger velocity stacks, 750 FD.
    79 SF parts bike.

  • #2
    Originally posted by red bandit View Post
    Brent, I know it's supposed to be 20in. Sorry if I made it sound like you were wrong. The only thing I have never checked is valve timing. But if valve timing is off that bad wouldn't I have lower compression (175psi)? 39 MPG. It seems to run great. I say "seems" because I have never had it on a dyno or road with another 11.
    No apology needed, as I already knew my statement was correct. To add, that vacuum at sea level is normally 22in.vac. and at 10-12,000ft. elev. it drops to 16in. vac. I just know this from using a mas-port vacuum pump at a variety of elevations, which was work related at the time.
    81H Venturer1100 "The Bentley" (on steroids) 97 Yamaha YZ250(age reducer) 92 Honda ST1100 "Twisty"(touring rocket) Age is relative to the number of seconds counted 'airing' out an 85ft. table-top.

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    • #3
      Also, those variations of vacuum based on elevations is why these vacuum slide/metering rod operated carbs are altitude compensating to a certain extent......less vacuum equals less rise of slides/metering rods that push up against vacuum slide sring assembly, which in turn equals less fuel/air as elevations rise.
      Last edited by motoman; 09-04-2017, 04:20 PM.
      81H Venturer1100 "The Bentley" (on steroids) 97 Yamaha YZ250(age reducer) 92 Honda ST1100 "Twisty"(touring rocket) Age is relative to the number of seconds counted 'airing' out an 85ft. table-top.

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