Scorpa SY-250R Clutch Lever Effort

Discussion in 'Trials' started by StuInFH, Oct 29, 2013.

  1. StuInFH

    StuInFH Been here awhile

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    2004 Scorpa with Yamaha engine

    I want to make the clutch pull easier for long, challenging trail rides (like back and forth on the Rubicon/Fordyce, etc.). It works perfectly now with master, slave, lever, arm, and plates all operating smoothly. But I've been spoiled by running 4 out of 6 clutch springs on my Sherco and after 40 or 50 miles of boulders I could use a lighter pull.

    I pulled one of the five springs and saw yellow marking paint on it.

    Anyone know the PN for lighter springs?

    Or source for these "high hat" washers to reduce preload that I have read about?

    Reluctant to call dealer to learn if there is a spring from a smaller bike like the 125 that will work because all they seem to do nowadays is look up PN by yr/model, but I would be pleased to learn otherwise.

    Solutions?

    thanks
    #1
  2. lineaway

    lineaway Long timer

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    Never had the tyz motor. But being it is a slave on the regular clutch arm, can you make a 1/2 to 3/4 extension on the arm and still get the slave to work?
    #2
  3. StuInFH

    StuInFH Been here awhile

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    Thanks, that is an option I am considering. I think swapping springs would be easy and the math is simpler. :-) One of the threads I found in my hours of searching was about Motobene's (I think) mod of a Montessa arm, I think. Would like to keep lever travel and engagement the same, with just less spring force would be nice.
    #3
  4. lineaway

    lineaway Long timer

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    No, the Yamaha motor was not designed for hydraulics. Scorpa bastardized the clutch to make it seem modern. So the easiest solution is what we did with cable clutches. My old Fantic was as easy as the Sherco. Sure you can play with the springs, gasket and slipping clutch and hours of work If you find that easier.
    #4
  5. DrKayak

    DrKayak Retro Rider

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    Stu,

    I think the "top-hat" washers on the Evo 300 actually increase the preload over a flat washer. In stock mode the neck of the washer sits down in the spring. If you want more preload you flip them over and the neck acts like a shim making the washer thicker. Beta also has optional thinner friction plates giving several configurations.

    You could take up rock climbing so your hands will be stronger? Works for me.. :deal

    I think Fordyce got too much snow to be ride-able this weekend.
    #5
  6. StuInFH

    StuInFH Been here awhile

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    Translation please? I have an Easy Pull on my CR clutch, works great. And I could use a different pivot point on lever, like Mtn Engineering's lever, but that would change engagement, no?
    #6
  7. StuInFH

    StuInFH Been here awhile

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    Huh? I was reading in a thread that a fellow used the washers to reduce preload and Motobene shared the math that was involved with spring rates and compression and advised simpler and cheaper solution than the washers was to remove a couple of springs (like someone did on Sherco). I'm pretty sure I recall that conversation correctly cuz Motobene's math forumulas were in there, but let me know somebody.

    And thanks for the working out suggestion, like the answer to 530 overheating issue, ride faster! lol
    #7
  8. lineaway

    lineaway Long timer

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  9. StuInFH

    StuInFH Been here awhile

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    Thanks.

    Just skimmed all Motobene's thread contributions, took two weeks. ;-) Didn't find the one from fellow who reported use of top hat washers (thanks for correct term DrK), saying they were "$$$" and that he had to relieve inside of cases for clearance. But I did find another thread by MB discussing springs and such that was fun to read.

    I would take a spring in to dealer and match it up to one similar except for smaller diameter wire, but when I called the dealer the kid could only order OEM ones by the year and model, no clutch springs in stock! Oh, and he had no records/reference for the 4GG motor.

    Still looking for lighter springs, thanks all.
    #9
  10. lineaway

    lineaway Long timer

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    So were you trying a Yamaha dealer? Have you ever tried Mike Komer at the Tryals Shop? By the way I realize that arm is strange, but if you have room a good welder could fabricate a short extension into the arm.
    #10
  11. StuInFH

    StuInFH Been here awhile

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    Thanks for the suggestion, but I don't wish to change anything affecting the engagement except maybe drag with motor off (which lighter springs will help). If I can find some lighter springs by searching or bringing in calipers to a shop that has springs, I'll be set. Will give Mike a call, thank you.

    Did finally find (with correct term) the posting by SCExpat reporting use of different washers and reply by MB, so at least I have my mind still. :-)

    <TABLE style="WIDTH: 100%; mso-cellspacing: 0in; mso-yfti-tbllook: 1184; mso-padding-alt: 2.5pt 2.5pt 2.5pt 2.5pt" class=MsoNormalTable border=0 cellSpacing=0 cellPadding=0 width="100%"><TBODY><TR style="mso-yfti-irow: 0; mso-yfti-firstrow: yes; mso-yfti-lastrow: yes"><TD style="BORDER-BOTTOM: #f0f0f0 1pt inset; BORDER-LEFT: #f0f0f0 1pt inset; PADDING-BOTTOM: 2.5pt; PADDING-LEFT: 2.5pt; PADDING-RIGHT: 2.5pt; BACKGROUND: #333333; BORDER-TOP: #f0f0f0 1pt inset; BORDER-RIGHT: #f0f0f0 1pt inset; PADDING-TOP: 2.5pt; mso-border-alt: inset windowtext .75pt">Originally Posted by SCExpat <?xml:namespace prefix = v ns = "urn:schemas-microsoft-com:vml" /><v:shapetype id=_x0000_t75 stroked="f" filled="f" path="m@4@5l@4@11@9@11@9@5xe" o:preferrelative="t" o:spt="75" coordsize="21600,21600"><v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path o:connecttype="rect" gradientshapeok="t" o:extrusionok="f"></v:path><?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:eek:ffice:eek:ffice" /><o:lock aspectratio="t" v:ext="edit"></o:lock></v:shapetype><v:shape style="WIDTH: 15.05pt; HEIGHT: 12.5pt; VISIBILITY: visible; mso-wrap-style: square" id=Picture_x0020_1 href="http://advrider.com/forums/showthread.php?p=22560842#post22560842" type="#_x0000_t75" alt="Description: View Post" o:button="t" o:spid="_x0000_i1025"><v:imagedata o:title="View Post" src="file:///C:\Users\frazers\AppData\Local\Temp\msohtmlclip1\01\clip_image001.gif"></v:imagedata></v:shape><o:p></o:p>
    I also got some of the special "top hat" washers ($$$) and this decreased the lever pull without removing any springs. It is not perfect, but much better and I am happy with it now.<o:p></o:p>
    </TD></TR></TBODY></TABLE>Thanks for sharing that! Top-hat washers sound like the back off on the clutch springs preload. Given the simple helical compression spring formula, k=fx or rather f=k/x (the force you get from the spring is its constant value divided by the amount you compress it). It's a linear relationship, so if you back off on preload, you back off on force. This reduces force with respect to lever travel over the whole travel range. Lowering the net spring force on a pressure plate is a great way to take some evil out of clutches. Lower net spring force will make it easier to one-finger modulate, and it will reduce both grabbiness and drag.

    There is another way to do this without buying parts, and it is SO easy to do and easy to reverse if you encounter mental problems with it. If you have a 6-spring clutch, simply remove two on opposite sides. Whether you decrease preload on 6 springs or remove two the effect is the same.
    #11
  12. motobene

    motobene Motoing for 44 years

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    What, some don't like my long postings?? :evil

    You said up front 5-spring clutch, so you don't have spring-removal options. A very cheap option is to back off on clutch spring preload. No fancy top hat washers needed, just shim under the spring washers with washer smaller in diameter than the inside coil diameter of the springs to reduce preload. Make sure the screws aren't out far enough when tight to rub on the clutch cover.

    But if a cable-style clutch arm lengthening can be easier. How much you lengthen will depend on whether it releases fully early enough, giving you plenty of room to reduce lever pull force. Long extensions may require a repositioning of the cable stay sop the approach angle doesn't make the cable rub over a curve.

    No substitute for good cable with oil (not light spray) as a lubricant that runs down the cable and eventually drips out the bottom end.
    #12
  13. StuInFH

    StuInFH Been here awhile

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    Re length of answers, I was only teasing in an appreciative way. :-)

    I almost wish it still used a cable, the Moose Easy Pull I put on my CR250 works great.

    I'll check clearance from sidecover, never much it seems, although they obviously weren't very concerned with overall width back when they were making this mx lump. Thought of using longer fasteners to back off preload, but figured not enough clearance to help much. May relieve the case a bit if I have to. Will try to visualize your suggestion, not seeing it right now. :-(

    Read 100+ posts RTW re this and saw bigger MC as most common solution. I asked Mike at Tryals Shop about using a larger one and he said when they were doing support for Scorpa at the World Rounds all the riders switched to one. $150 is a bit pricey though.

    I'm working to source some softer springs, like the Splatt Shop sells for the Sherco. Chris was very helpful in giving me all the dimensions. Yamaha and Barnett, not so much.

    And I lost track of how many "man up" comments I came across, but I did count the number of riders that followed me end to end through Little Sluice on the Rubicon last two weekends. :D

    I'd like my wife to be able to ride this bike (who is a rock climber lol) and I don't want her to have to man up. Sorry, guess I had to rant a bit, just a drag that asking a question and/or reading replies on the internet is 90% a waste of time. (Did you know that removing springs will cause clutch to slip and if you lose cell signal your smartphone won't work as a GPS? :huh)

    Thanks for being the 10%, Hooke's Law and all that. :thumbup
    #13
  14. motojunky

    motojunky Professional Idiot

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    Right up front, I admit to not having read the previous replies thoroughly (busy!). :D

    I have a 2002 SY250 and find the clutch to be very minimal effort. On par with the new 2012 Sherco I recently spent a few hours on. I see that you're running 4 of 6 springs on your Sherco... was the effort of the stock Sherco higher than you liked as well? Just trying to get a frame of reference...
    #14
  15. StuInFH

    StuInFH Been here awhile

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    If you had read above, you'd know the problem is with me. lol

    Yeah, the pull is easy enough for trials, but I'm setting the bike up for an all day trail bike for Rubicon and Fordyce, if that means anything to you. If I can get the lever pull down to my girlie-bike 690R, I'll be happy.
    #15
  16. motojunky

    motojunky Professional Idiot

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    Just man up!




    Sorry, couldn't resist. :lol3 I'm following this with interest - mainly 'cause it's nice to read about a Scorpa once in a while. I wonder if you contacted an aftermarket clutch company (is Barnett still around?) with the spring measurements they'd be able to do the cross-referencing that the dealer can't?
    #16
  17. StuInFH

    StuInFH Been here awhile

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    Yeah, I only expected to hear from you. It seems no matter how much background I gave first or how direct my questions, I got the same stuff, or nothing. Like I said above, Barnett no help. I asked for dimensions of 250 and 80 YZ springs (125 and 250 are the same), hoping I can match some up, like this "Looking for springs that I can use that are ~30% lighter than OEM. Do you have the dimensions for 250 and 80 YZ springs, including wire diameter and/or spring wt? thank you" and "Mike" said, "Stuart, Afraid all of the springs we make are stronger than stock. That's what we normally make. Sometimes they are close to stock, but never lighter. Sorry!."

    No sheet. Now about those dimensions I asked for?....sheesh. I clarified my request, even giving them their PNs, but then got silence (maybe they'll get back to me Monday with their secret numbers).

    Best response was from some bozo on thehellteam in OZ who, after I explained I had 5 springs, told me removing springs will make it slip and if I want a lighter clutch to get a GG. and we wonder why the sport just fizzles...

    Chris at Splatt Shop gave me ALL of the dimensions of their soft springs, real nice guy. And Mike at Tryals Shop was very helpful too.

    If you wanna talk Scorpa, I can post up how I love the bike for the Rubicon over the Sherco (that suffered broken frame downtubes from a mild huck off a boulder). And then I'll wait for folks to tell me to get a modern bike with a REAL trials motor. :-)
    #17
  18. Luke

    Luke GPoET&P

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    A couple of thoughts:

    How about taking some stock springs and cutting coils off them? It'll make the spring rate higher but the force will be lower because the preload will be less.

    Or, how about industrial spring suppliers?

    Google brought up an ad for these guys: http://www.springsfast.com/
    They have lots of available springs.

    I guessed 0.6" od x 1.25" long and got these:

    <table id="prodchart" style="font-family:Verdana, Geneva, sans-serif; font-size:11px; background-color:#e1e1e1;" border="0" cellpadding="3" cellspacing="1"><tbody><tr style="background-color:#ffffff;"><td style="text-align:left;" nowrap="nowrap" valign="top">Part Number</td><td style="text-align:center;" valign="top">Outer Diameter in.</td><td style="text-align:center;" valign="top">Wire Diameter in.</td><td style="text-align:center;" valign="top">Overall Length in.</td><td style="text-align:center;" valign="top">Rate
    lbs./in. of travel</td><td style="text-align:center;" valign="top">Load lbs.</td><td style="text-align:center;" valign="top">Material</td><td style="text-align:left;">
    </td></tr><tr style="background-color:#ffffff;"><td align="left" nowrap="nowrap">C20-045-040</td><td align="right">0.600</td><td align="right">0.045</td><td align="right">1.250</td><td align="right">8.00</td><td align="right">7.73</td><td align="right">MUSIC WIRE</td><td align="left" nowrap="nowrap">Pricing / Order</td></tr><tr style="background-color:#ffffff;"><td align="left" nowrap="nowrap">C20-049-040</td><td align="right">0.600</td><td align="right">0.049</td><td align="right">1.250</td><td align="right">12.80</td><td align="right">9.1</td><td align="right">MUSIC WIRE</td><td align="left" nowrap="nowrap">Pricing / Order</td></tr><tr style="background-color:#ffffff;"><td align="left" nowrap="nowrap">C20-055-040</td><td align="right">0.600</td><td align="right">0.055</td><td align="right">1.250</td><td align="right">18.50</td><td align="right">12.6</td><td align="right">MUSIC WIRE</td><td align="left" nowrap="nowrap">Pricing / Order</td></tr><tr style="background-color:#ffffff;"><td align="left" nowrap="nowrap">C20-059-040</td><td align="right">0.600</td><td align="right">0.059</td><td align="right">1.250</td><td align="right">23.90</td><td align="right">15.3</td><td align="right">MUSIC WIRE</td><td align="left" nowrap="nowrap">Pricing / Order</td></tr><tr style="background-color:#ffffff;"><td align="left" nowrap="nowrap">C20-062-040</td><td align="right">0.600</td><td align="right">0.062</td><td align="right">1.250</td><td align="right">30.50</td><td align="right">17.5</td><td align="right">MUSIC WIRE</td><td align="left" nowrap="nowrap">Pricing / Order</td></tr><tr style="background-color:#ffffff;"><td align="left" nowrap="nowrap">C20-067-040</td><td align="right">0.600</td><td align="right">0.067</td><td align="right">1.250</td><td align="right">35.00</td><td align="right">21.7</td><td align="right">MUSIC WIRE</td><td align="left" nowrap="nowrap">Pricing / Order</td></tr><tr style="background-color:#ffffff;"><td align="left" nowrap="nowrap">C20-072-040</td><td align="right">0.600</td><td align="right">0.072</td><td align="right">1.250</td><td align="right">45.00</td><td align="right">26.5</td><td align="right">MUSIC WIRE</td><td align="left" nowrap="nowrap">Pricing / Order</td></tr><tr style="background-color:#ffffff;"><td align="left" nowrap="nowrap">C20-080-040</td><td align="right">0.600</td><td align="right">0.080</td><td align="right">1.250</td><td align="right">82.00</td><td align="right">35.4</td><td align="right">MUSIC WIRE</td><td align="left" nowrap="nowrap">Pricing / Order</td></tr><tr style="background-color:#ffffff;"><td align="left" nowrap="nowrap">C20-085-040</td><td align="right">0.600</td><td align="right">0.085</td><td align="right">1.250</td><td align="right">107.00</td><td align="right">41.8</td><td align="right">MUSIC WIRE</td><td align="left" nowrap="nowrap">Pricing / Order</td></tr><tr style="background-color:#ffffff;"><td align="left" nowrap="nowrap">C20-091-040</td><td align="right">0.600</td><td align="right">0.091</td><td align="right">1.250</td><td align="right">154.70</td><td align="right">50.3</td><td align="right">MUSIC WIRE</td><td align="left" nowrap="nowrap">Pricing / Order</td></tr><tr style="background-color:#ffffff;"><td align="left" nowrap="nowrap">C20-100-040</td><td align="right">0.600</td><td align="right">0.100</td><td align="right">1.250</td><td align="right">203.00</td><td align="right">64.9</td><td align="right">MUSIC WIRE</td><td align="left" nowrap="nowrap">Pricing / Order</td></tr></tbody></table>
    #18
  19. motobene

    motobene Motoing for 44 years

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    I'm puzzled about the 'bigger' master cylinder comments. There is a similar idea with the HRC 4RT with riders spending money on a 'larger' master cylinder with exact same piston diameter and lever ratio and perhaps just a larger reservoir. this does not affect lever pull, clutch quickness, etc. It just lightens the wallet and a psychological effect of it working because money was spent. If a larger master cylinder piston diameter is used, it increases force, not decreases it.

    Here is a summary of what reduces lever pull with hydraulic clutches (I may forget some:

    - Lubricating the lever pivots and contacts

    - Setup for better ergonomics like:

    - Moving the master cylinder inboard some to run the index finger farther out on the lever (adjust the lever stop and engage point accordingly)

    - A master cylinder with a smaller piston diameter (if it's already 9.5mm you'll have no alternatives)

    - A larger slave cylinder diameter

    - Reduction in preload on the clutch springs (just a little reduction multiplied by all springs is significant)

    - Removing two springs on a 6-spring clutch

    - Fitting some or all clutch springs that are softer = smaller wire diameter, slightly larger outside diameter and more turns in the coils

    - Rider skill level

    The last point is indirect of course, but some riders wear out their arms more quickly that others. This isn't a man-up comments, but just stating the perhaps un obvious.

    I've noticed a correlation between complaints of arms and hands wearing out and rider skill level. As skill level goes up, the body and legs become more dynamic and forceful, and arm and hand inputs become more brief and pulse-like. While more advanced riders tend use the clutch often and more, the arms are relaxed much of the time. More correct body position for turning, for example, results in a little palm pressure, thus reducing the need to clamp onto the bars. Initiating turns more with the legs reduces arm force a s well.

    Did I miss something?
    #19
  20. motobene

    motobene Motoing for 44 years

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    Given the end of the springs is a bit coil bound, decreasing preload by grinding will have a positive effect. But unless you have a very good belt sander, grinding springs can be a royal pain. If you heat the coils up to orange, which can happen fast, you take heat treat out of them and the heated up part of the coil can collapse.

    As for trying other springs, if you can find the near equivalents, why not? In the table they give you k in pounds per inch, so you know stiffness. You'll need not just springs but those that have ground ends so they don't cock on an angle when preloaded.
    #20