ThunderMax® Adjustable Idle on a 2011 Road King®

A lower idle will help your EFI H-D® Big Twin run cooler and improve the sound of your exhaust. This new “Low Idle” video demonstrates the adjustable idle feature available in the ThunderMax tuning software. This feature is available for both cable-throttle and throttle by wire applications. Tel: 410-579-3828. Zippers. ThunderMax.

Zipper's

10 Responses to “ThunderMax® Adjustable Idle on a 2011 Road King®”


  1. 1 A 1 CYCLES Jun 22nd, 2011 at 9:43 am

    i dont see how lowering idle will lower engine temps…it will trun oil pump slower and increase oil temp, decrease oil pressure and volume? seems like it would run hotter

  2. 2 fuji Jun 22nd, 2011 at 10:04 am

    A 1 CYCLES.

    You are absolutely right.

    Years ago on my old scoot my mechanic at the time made me raise the Revs to no less than 1000 for better oil circulation for cooling. I liked the sound below 1000 but one does damage.

  3. 3 Magnumbob Jun 22nd, 2011 at 12:07 pm

    While I would be hesitant about setting a customer’s bike to idle that low, I do idle my own 103″ TC at 850 rpm via HD’s Super Tuner, as I did my personal 95″TC before it (65k, no problems) and my 88″TC before that (68k no problems).
    Note that although older big twins are generally set to idle lower than that, they all had less displacement and heavier flywheels too allow them to idle smoothly at the lower rpm. As soon as you put a set of lighter, stroker flywheels in, they didn’t idle as smooth either. Seat of the pants tells me idling a TC below around 800 feels too clunky as the motor drastically slows down on the compression stroke and speeds up quickly on the power stroke.
    Just like all of you, I’ve been beat over the head with all the reasons you should never idle an Evo or TC below 1000, but I’ve never first hand seen it to be a problem. I’ll bet the vast majority of carbureted Evo and TC owners that do their own work have their bikes idling well below the recommended 1000.
    As to the heat issue, remember that Harley’s own injection map drops the idle RPM to 800 in extreme high heat conditions. I’m pretty confident it’s not to make it run hotter. It may be true that the oil isn’t circulating as fast, but the engine isn’t generating as much heat either.
    If you don’t believe it, simply idle your bike at 2000 rpm on a hot day and see what happens.

  4. 4 Richard Jun 22nd, 2011 at 2:53 pm

    I look at it this way….800rpm is 20% slower than 1000rpm. Therefore there will me 20% fewer power strokes resulting in 20% less heat being generated. My gut tells me that oil volume at those slow speeds is likely a non-factor….

  5. 5 A 1 CYCLES Jun 22nd, 2011 at 4:30 pm

    richard…like your math but..20% less oilf low to get to the cooler. if there is one..20% less flow to cool the parts that are still making heat regardless, and it isnt just power strokes creating heat..its also tons of friction, rings bearings, pumps cams, rokaer arms…lots of heat. cant hurt to run them at 900 to 1000…is the way we will continue to do it at my shop..wrong or right.

  6. 6 A 1 CYCLES Jun 22nd, 2011 at 4:33 pm

    love tech articles on here instead of haters picking on bikes…thank you all for the intelligent responses.

  7. 7 Bradley K Jun 22nd, 2011 at 9:47 pm

    950 to 1050 rpm’s. Any less & I feel you will be taking an unecessary risk.

  8. 8 ROGUE Jun 23rd, 2011 at 6:52 am

    I have the ThunderMax on my 2009 FLHTC and I am very happy with it.
    I have 18,000 troble free miles on it.
    I recently downloaded the software that allows me to change idle, max rpm and even the different programs I have stored in the ecm.
    I personally run my idle RPM around 900 and that is because of air cleaner and exhaust.
    Those that have other engine modifications may chose a different idle.
    Harley does give the owner of the motorcycle the option of dropping a cycliner at idle if engine gets hot. I do not use this but to each his own.
    With that said The ThunderMax works very well and as advertised. It is up to the person purchasing it to determine if it does what they want it to.
    Not everyone wants the same out of their engines and motorcycles

  9. 9 tom wroblewski Jun 23rd, 2011 at 11:01 am

    Great responses ‘;’;’;’

  10. 10 John Botts Jun 23rd, 2011 at 11:25 am

    On Power Commander’s Power Vision tuner website, it states that although you can change the idle speed to whatever you want, they don’t recommend below 1000 rpm, as it can cause an issue with oil pressure in Twin Cam engines.

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