Need you're guidance!

Discussion in 'Airheads' started by sh1bby69, Oct 29, 2012.

  1. sh1bby69

    sh1bby69 Been here awhile

    Joined:
    Aug 17, 2010
    Oddometer:
    635
    Location:
    Orange County, CA
    Some of you may know I picked up a '79 R100RT to be my tug for my hack. Before I mount it I want to go through the bike and have it tuned up. I'm still consider myself a noob working on Airheads. So I want to know how you would go about tuning the bike. As for how the bike sits so far, it'll idle but kind of rough. I bought it from a gentalman from Missouri and the bike has been sitting for 2 years. I do notice a leak around the oil pan and oil drain plug so I know I'll have to replace the gasket and o-ring. Lately it's been tough to start, maybe it's cause the tank is almost empty...but when starting it sometimes it'll back fire pretty good. Almost like a gun shot. Also sometimes when trying to start it it'll make a spinning noise like the starter is not catching...i dunno. Can anyone help with trouble shooting with the issues so far?
    #1
  2. Mark Manley

    Mark Manley Long timer

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    Back home in the UK
    I would start by giving the bike a full service, drop the sump and clean it out, drain the tank and carbs, new plugs, caps and leads, check valves and points if it has them, then see what you have from there.
    #2
  3. sh1bby69

    sh1bby69 Been here awhile

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    Aug 17, 2010
    Oddometer:
    635
    Location:
    Orange County, CA
    Sounds great! Easy enough!
    #3
  4. boxerboy81

    boxerboy81 Stay Horizontal

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    Jul 22, 2009
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    3,096
    Location:
    Melbourne, Oz
    YOUR advice is good. Ensure you don't over tighten those sump bolts as they only need to be a poofteenth past finger tight to do the job.
    #4
  5. sh1bby69

    sh1bby69 Been here awhile

    Joined:
    Aug 17, 2010
    Oddometer:
    635
    Location:
    Orange County, CA
    Anything different about tuning a bike with dual plugs? Valve spacing different?

    Sent from my Galaxy Nexus using Tapatalk 2
    #5
  6. disston

    disston ShadeTreeExpert

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    Mar 22, 2011
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    Does this bike have dual plugs?

    The valves are set the same.

    The timing on a dual plugged bike is usually not the same as stock. But it's a more involved discussion.

    Some methods for balancing carbs don't work so well on a dual plugged bike. For instance the shorting method doesn't work so well. But there are ways to work around this.
    #6
  7. sh1bby69

    sh1bby69 Been here awhile

    Joined:
    Aug 17, 2010
    Oddometer:
    635
    Location:
    Orange County, CA
    Yes the bike has dual plugs.

    Sent from my Galaxy Nexus using Tapatalk 2
    #7
  8. disston

    disston ShadeTreeExpert

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    I don't know enough about the history of the bike or the rider. Here's what you need to know. When dual plugging was originally set up was the ignition tailored for this. Dual plugging involves customizing the ignition curve sometimes no more that just making sure the F dot is not in the window at full advance. Ignition timing needs to be retarded for dual plugging because two plugs burn the gas faster.

    So when you put a timing light on the timing window and time the bike, what sort of picture do you get in the window, at idle? At 3000 rpm?

    There should be a custom mark of some sort, usually a paint dot, on the flywheel. May also be a dot hammered into edge of flywheel with a hammer and chisel. This mark should appear before the OEM dot when turning the engine in the direction of normal rotation.

    Again the point is a dual plugged engine needs custom timing and if you didn't build this thing then the person who sold it to you should have told you something about it.
    #8
  9. Boxer Metal

    Boxer Metal Mad Scientist

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    Nov 3, 2003
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    Location:
    Chico, California
    Start with a valve adjustment, then check the timing and it is different for dual plugging then adjust the carburetors. From there you have a good base point.
    #9