View Poll Results: Do you use the manual advance/retard option?

49. You may not vote on this poll
  • Always and actively

    20 40.82%
  • Only when kick starting

    25 51.02%
  • Occasionally when I remember

    1 2.04%
  • Never bother or disconnected it

    3 6.12%
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Thread: Ignition Advance

  1. #1

    Ignition Advance

    Do you actively use the ignition advance/retard other than when kick starting a bike?
    Buzz Kanter
    American Iron Magazine Harley forum
    American Iron Magazine Digital Delivery

    "It is always fascinating to watch the development of rationalizations for an argument"

  2. the factory put it there for a reason and i use it when i start the bike only

  3. yes

    when sitting in traffic the old flathead gets to hot so I turn back the advance so the bike has vary slow idle then turn back half way to roll in traffic then full advance when traffic clears

    she rides like a train and stops like a boat

  4. Howdy Buzz,

    Absolutely, it's a dynamic as important as your throttle. To put it in perspective, the greatest gains in efficiency in the last decade with EFI systems have been in the area of ignition control and many of the earliest motorcycles relied on ignition advance/retard to control speed rather than the poor carbs of the day - it has an important bearing on efficiency and mechanical preservation.

    HP, ie, max torque or cylinder pressure generally occurs at about 15-18 degrees after TDC with full flame propogation. Imagine standing there, hammer in hand, hitting your piston with the head removed to achieve the most efficient transfer of energy to the crank. Hit it too soon after TDC and rod/main bearings must absorb that energy as the rod angularity at that point prevents translating that energy transfer into crank rotation. Too late and the energy from your blow is dissipated or partially lost as the piston approaches/swings through BDC.

    Our old machines (flat heads and Four cylinder F heads especially) are inherently inefficient resulting in alot of residual partially combusted ignition byproducts which lead to accelerated ring/cylinder wear even when ridden with a conscious effort to provide the right advance for the situation. Unlike OHV/OHC motors, especially with Fours, operating one too far on either side of the ideal setting is is hard on them. They carbon up pretty quickly when run either retarded or too advanced - if the heat from retarded settings doesn't do them in first - and motors still fitted with babbit bearings can experience rod bearing failure in pretty short order if asked to absorb too much advance, or worst yet accomodate detonation under load.

    Start it it and idle it retarded, but from there, any situation where the engine's put under load (cylinder pressure gain) - as opposed to lift throttle or light cruise - I'd vary the ignition advance if for nothing else, out of mechanical empathy.
    Last edited by peterg440; 06-12-2008 at 10:13 AM.

  5. thanks Peter good info, nice to know the reasons why

    one night during a group ride is was playing with the advance, and found out how to shoot fire out of the pipe, and everyone thought how cool! till the next day when I had to clean the plugs, not so cool
    Last edited by stevodigitalfly; 06-12-2008 at 11:45 AM.

  6. Howdy Steve,

    You'll notice I didn't mention rings here. That's one area where these motors, when fitted with old fashioned fat compression rings utilizing tension - as opposed to the thin ones using gas expansion - are very tolerant of detonation and carbon. Modern ring technology assumes two criteria in their design that we do not meet with our old motors: accurate spark and fuel control. Modern iron rings do not like dirty combustion chambers and will wear quickly when exposed to excess carbon. Though immensely strong/efficient they can be pulverized and the ring lands damaged by detonation, so it's something to keep in mind when fitting those expensive forged pistons with Mahle rings to that lusty 80 incher you plan to scare Gold Wing riders with on the highway. As the Nascar guys say, you've got to be a little more "up on wheel", no more set and forget.

    I was on an AMCA road run in the Ozarks with a chap on a freshly built Chief motor with all the goodies who ruined it in only the second day, miffed, his previous build had lasted 10,000 miles - but that was with some forgiving old 4 ring Egge slugs absorbing the punishment.

  7. I got one for you
    when I use the sidecar the bike sits straight up, and then I need to advance the advance, what do you make of that?
    Last edited by stevodigitalfly; 06-14-2008 at 07:42 PM.

  8. I went for a group ride fri night for about 3 hrs, with the wife in the sidecar.
    and I know you dont believe me, but I had to move up the advance about 1/4 inch. at full retard she wont start and at full advance ain't enough, give it a 1/4 inch twist and all is well.
    I removed the sidecar just now and will ride in the morning and tell you how it goes
    Attached Images Attached Images

  9. Ok
    went for a ride today with the advance 1/4 more than usual, (sidecar setup) and the top end is great, she was screaming at about 85mph but when starting is wish I was a little more retarded, (ha ha) but she didn't kick back so I will leave it for now and see how the next cold start goes
    Last edited by stevodigitalfly; 06-17-2008 at 11:47 AM.

  10. #10
    Jack Hester Guest


    Just rode the '59 FLH (my rolling restoration) down to Farmington, NC. 125 miles one way, from near Roxboro. Lots of curves and hills, and no Interstates, as was my intention. Whenever I loaded the engine for any reason, I could back off the spark just a bit, and feel the engine take a second breath. I've experimented with it for years, and found what the engine likes under different loading. Of course, when I do a complete rebuild on it, all that will change somewhat. But, it's all in the feel. So, it won't take long to figure it out.

    On a side note. Farmington hosted the '08 Smokeout, put on by The Horse magazine. I went because I used to frequent the place back in the 70's and 80's, at the all Harley drags. Haven't been down there in about 20 years. As expected, lots of new machines and posers to go along with them. But, a fine showing of old machines and old geezers to well represent them. It was like going to a state fair. Side shows everywhere. But, met some really fine folks, as they were attracted to my machine like I was to the other 'older' machines.

    It's worth the venture out to see another part of motorcycles. Those will be the geezers of tomorrow. No telling what they'll be riding. Whatever we preserve for them, I hope.


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