2013 Beta Evo clutch performance

Discussion in 'Trials' started by DrKayak, Sep 28, 2013.

  1. motobene

    motobene Motoing for 44 years

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    Lineaway, I think you agree that less pull, better quality disengagement/engagement, and less drag help the average rider. My apologies for implying you were fear mongering separate from direct experience. I am not the least motivated to suggest technical tweaks that will break bike or body, so implying that will happen has my rapt attention.

    So given your direct experience, please be more specific. "Hard to deal with" isn't specific, and CAN have some "huge problem" is... well, ~:eek1

    I get your point about higher skill riders, but humans are analog devices. Abusiveness does not correlate so tightly with skill. Many high-skill riders are very machine aware and won't be out killing themselves by burning a clutch to a crisp then doing a splatter wall. And clutches anywhere near sprung correctly don't digitally go to zero toque resistance when loaded. Unless a rider is super machine unaware, a slipping clutch will be felt and he or she or their aware friends will know and deal with it.

    The technical issue itself is also analog, and not about number of springs but about net clutch clamping force with respect to a very wide number of variables. Taking out two springs is just a simple way to learn if you are in a more optimal range for your bike and application, or not. Nothing better than educating, direct experience.

    I don't act out of fear regarding technical things, and if anyone reading this is fearful about the 10-minute mod, don't do it, simple as that!
    #41
  2. laser17

    laser17 Been here awhile

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    My dad made light belville springs for the GG for years. They really made a huge difference on the older bikes, and then in 06 GG followed his lead and reduced the spring K by 20% and eliminated the big need for them, although there was still a benefit to the smaller bikes. (The thinking here was a 250 could get away with a even lighter spring than a 300)

    On my 250 - I could get my super light spring (spec'd for a 125) to slip on the road in a tall gear, but never in a section. People were always surprised at how light it was. I had a expert rider try it and he didnt feel any slip, but the engagement was way too slow for him. I liked it that way - super progressive, but slow as mud. Probably the least drag on a GG as well. (With the blue smurf oil)

    The 1st year he made them, I got REALLY fast at switching clutch springs as I was testing the various thicknesses. As MotoB said before, the thickness of the spring has a 4th order effect, so you could really feel the difference of a couple thou in thickness. There was a real sweet spot of about 10% less force than the 06 spring - much more than that, and you could slip it with the blue stuff. Throw in ATF-F and it was OK down to 20%.

    Unfortunately, the guy who made them (a friend of mine from HS) died and we couldn't find the tooling he was using to make them. He pressed them flat before machining them and maintained a flatness spec tighter than the OEM incoming springs. He also left a small full thickness collar at the ID. So they are no longer. Was a fun project though.
    #42
  3. lineaway

    lineaway Long timer

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    Bene, I replied with a long post that got zapped. So long story short version. Had a mechanic that I worked with. We argued over clutch adjustment and mods. Two years later he became our state champ. He was our first rider that could splatter off flat ground and made it look easy. So nothing wrong with making your bike better for the level that you ride at. But if you want to be a top rider, the way it comes from the factory is probably the way it should be ridden.
    :D
    #43
  4. StuInFH

    StuInFH Been here awhile

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    I have to totally agree with you here and will be putting my 2 springs back into my Sherco clutch. Personal experience got me hurt bad.

    During a 40 mile ride I climbed a longer hill climb than found in any trials section around here, Cadillac Hill on the Rubicon, and I don't think I even used the clutch more than a couple times (during shifting), as momentum in 3rd and 4th was working great on that long, steep rock pile. I detected no slipping, but the next day my calves were really HURTING!

    Must have been those 2 missing springs. :lol3

    just teasing, enjoying the back and forth. learning a lot here, keep it up :D
    #44
  5. lineaway

    lineaway Long timer

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    Now I agree that was funny. The only time my calves ever hurt was riding a two day in Pampa , Texas. The only obstacle were air logs. Flat, grassy ground and two or more logs in every section!
    #45
  6. motobene

    motobene Motoing for 44 years

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    Sometimes long posts are better off getting zapped, my own included!

    I read in The Economist yesterday morning an interesting article about Dale Carnegie and his insights into the role of emotion and logic regarding people.

    I apologize, lineaway. I was over working the issue with you and that stops here.
    #46
  7. lineaway

    lineaway Long timer

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    It`s all good `Bene. I just got back from a two day vintage. I could of used some help, especially between the ears!:huh
    #47