Small Rant Against Banshee Clean-Outs

Discussion in 'Trials' started by motobene, Apr 16, 2018 at 8:20 AM.

  1. motobene

    motobene Motoing for 46 years

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    This is a repeat rant, do pardon, but I hope it will help further the decline of the frenetic noise and smoke that comes with the cultural phenom of the banshee clean-out of two strokes.

    Whatever riders want to do to their bikes is their own business. Trials bikes are way tough so wringing a bike's neck at a million rpm unloaded may hurt nothing at all, but I find the resulting noise and smoke mildly irritating.

    Please feel free to disagree and challenge the technical merits of my thoughts.

    The admonition to repeat clean-out as some always rule of thumb, even by great riders, is in parts a self-perpetuating cultural phenom. Lacking may be a deeper understanding of air-fuel metering with respect to loading.

    The clean-out can create a false feedback loop that's I think maybe falling out of cultural favor, slowly, like running no idle as brakes did (think vintage bikes with little in the way of brakes).

    Rrringggdingdingding!blubbluh? Who crashed! :p3rry Oh... it's just a clean-out....

    Carbureted two strokes are jetted for various states of loading in a compromise and there are no sophisticated sensors and thousands of lines of code as with FI bikes. In some conditionals carbs don't meter well for the conditions. That they can meter well for what matter is what counts, so I prefer them for simplicity.

    Free revving a bike with only crank inertia loading, with the slide way up on the needle taper can cause 4 stroking on the way up to a million rpm. It's a Newtonian thing of equal reaction to an action. Fueling versus loading. The richness and smoke during the Rrrring and dingdingding phases can be misleading.

    The default over-rich stock main jets add - a little - to the unhelpful feedback, which is one reason I emphasize not sticking with stock main jets. Add altitude to stock main jets and the negative effects increase.

    Reasonably well-jetted two strokes that are not over oiled and don't have other things wrong do not need clean-outs after warm-up! If yours does, and won't rev all the way until you do, please don't consider that as normal.

    The only clean-out that more ideally should needed is coughing up of oil 'lungers' during loaded warm-up. A 2 stroke bike has sat one or more days will collected some oil in the bottom of the crank space.

    Since switching years ago to better premix oil, in my case Maxima Formula K2 full synthetic from a cheaper oil, I noticed notably fewer 'lungers' coughed up at warm-up. It's now like every fourth warm-up that I'll get a one-second hocker coming up, but that's it.

    I don't know the petrochemistry of why there is a difference. Maybe some of you do.

    My warm-up routine is to start the bike on choke for ~5 seconds, click the choke lock off, then pulse the choke at any bogging - no more than 10 seconds long unless it's very cold. TI gently ride around 20 or so more seconds to warm the top end. Then I click it up into third while creeping along, accelerating WFO for a few seconds to vacuum out the 'green stuff.'

    Done!

    Bidding a dieu to the cleanout!:super
    #1
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  2. Nodabs

    Nodabs Been here awhile

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    My Dad taught me a long time ago that unless there is a load on the engine, it won't clean out. And that was in the bad old days of castor oil and weak ignition systems.
    Don't get me started on the rocket scientists that rev their sport bikes up on the rev limiter all of the time. Morons!
    #2
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  3. 2whlrcr

    2whlrcr gooligan

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    I am not guilty.
    #3
  4. Gordy

    Gordy Team Listo

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    I usually rev mine to the moon after getting a clean.

    Happens once or twice/event. :rofl
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  5. heffergm

    heffergm Long timer

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    You'd love showing up to the paddock at your average hare scramble... guys on 4 strokes, WFO after a cold start, on the rev limiter until they stop missing. It hurts my mechanical heart.
    #5
  6. lineaway

    lineaway Long timer

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    The funny thing here, is Ryan was always one of the worst at this and all the RYP riders have followed suit.
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  7. lineaway

    lineaway Long timer

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    I just watch and wait for a cold stick to happen. Nothing like the big shit eating grin telling them they just nipped a piston.
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  8. MT 007

    MT 007 Been here awhile

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    Just posted a Ryan video earlier today on the video thread... at about the 2:00 minute mark he said "make sure the bike is in third gear and engine is very clean we need max power" before he hits a big splatter...
    #8
  9. VxZeroKnots

    VxZeroKnots Long timer

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    I was going to say before splatters and after not dying/crashing/dabbing when that seemed like a real possibility I'll rev it out.

    That being said what @heffergm said is 100% true, except it doesn't hurt my heart it hurts my ears.

    I will say revving out a trials bike is super disappointing without the sweet sweet sound of a PV warbling at full song.
    #9
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  10. grizCP

    grizCP DROC

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    I don't know why, but this post makes me happy - one of my favorite parts of scoring is watching people get pumped out of their minds after a hard-fought clean. If there is a good reason to let that banshee rip, this is it!

    [​IMG]
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  11. fprintf

    fprintf Adventurer

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    Man, I need more gifs from Twist of the Wrist II, such good acting!!!
    #11
  12. ChopperCharles

    ChopperCharles Long timer

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    I have *no idea* what this "banshee clean out" thing is. Care to enlighten?

    Charles.
    #12
  13. heffergm

    heffergm Long timer

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    Bike in neutral, handful of throttle .
    #13
  14. ChopperCharles

    ChopperCharles Long timer

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    Oh wow. That's... remarkably stupid.

    Charles.
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  15. MT 007

    MT 007 Been here awhile

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    the thinking is it "cleans out the engine" so when you snap the throttle you get a nice crisp response instead of a boggggg. I am not suggesting the thinking is correct.
    #15
  16. Brewtus

    Brewtus Buffoonery, Inc.

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    I'm guessing that you have never been to a National (or even a club event with Pro riders) have you? :D



    :nod
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  17. lineaway

    lineaway Long timer

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    The thinking is to have too much power vs falling to your death with too little effort.
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  18. lamotovita

    lamotovita DAMN SNOWBIRD!

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    Round here we call that a Mexican tune up.
    I rode a Trial last weekend at 6200' instead of the normal 2500' I'm used to. I didn't know how the leaky old Bing on my Bultaco would work, and the needle was already dropped all the way. I turned the air screw out and the idle screw in, with regular clean outs I had no problems with third gear splatters all day:D.
    #18
  19. motomofo

    motomofo Been here awhile

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    There is absolutely nothing wrong with revving a bike the moon before doing something like a big splatter, where you need all of (or almost all of) the power available. In reality though, only a small percentage of people are in that group (and probably none of us reading this). What gets me are the guys who’s bikes never get over 1/2 throttle in a section, but feel the need to rev its guts out beforehand. My bikes are always jetted and tuned properly, and none of them have ever had an issue with loading up.

    I’ve always noticed the way most trials riders do the quick 3ish blips of throttle right off idle when warming the bike up or before entering a section, looking for that almost instantaneous response, vs most two stroke MX/offroad racers who hold half throttle for a second or two, before before going WFO for a split second to clean out.
    #19
  20. motobene

    motobene Motoing for 46 years

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    Yup. The unloaded clean-out isn't the same as max throttle splatters. The latter bring load in after storing a bunch of energy in the flywheels.

    I think I'm too old for max throttle splatters. I might snap in half slamming into something that hard :-0
    #20
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