2017 Sherco 250 Factory

Discussion in 'Trials' started by motobene, May 14, 2017.

  1. mung

    mung Been here awhile

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    The Ohlins on my 04 Raga was also quite stiffly valved. I went considerably stiffer on the spring for my 250 pounds and then the valving was just about right to control the spring. As far as material for a shock body steel may not transfer quite as much heat but it is considerably stronger and longer lasting than aluminum. On my off roaders when you hit a 20 mile section of deep whoops the steel will stay together much longer than aluminum. After much use an aluminum body shock will take on a slight hourglass shape so then the seals do not work as well and things go downhill from there. For long term use steel bodies are the way to go.
    #41
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  2. 2whlrcr

    2whlrcr gooligan

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    This is the one that has my interest...

    [​IMG]
    #42
  3. Norman Foley

    Norman Foley Devotee of the Husqvarna

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    Mike Komer's son Aaron has a '17 250 SC Factory and it's sweet. I thought about getting a 125 Factory, as I liked the suspension on my '17 Gas Gas 125 and they use the same components. The Marzocchi forks and RV16 shock work just fine on my '17 125 SC standard though. I'd love to have the blue wheels off a Sherco Factory though!:-)
    #43
  4. motobene

    motobene Motoing for 46 years

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    Factory Scorpa uses same forks as Sherco, Tech.

    I should explain a bit more my comment on bare honed steel shock bodies and wear rate.

    Steel is stronger and expands less with heat. Steel shock bodies are considered to be tough. In terms of surface durability and keeping oil cleaner, well anodized aluminum and especially hard coated aluminum bodies are better because what touches the piston band is extremely hard, much harder than shock body steel, though the aluminum substrate is softer than steel.

    Some if the 'fade' in over-heated shocks is simply from the radical change in oil viscosity, not the bodies belling out.

    Some of the idea of aluminum-body shocks belling out is from the long era of honed bare aluminum shocks with low bore surface hardness. Strokings would slowly slough off aluminum particulates and over time the oil would end up looking like silver paint which accelerated the wear rate. The bores would not yield plastically so much as enlarge in the stroke path from wear. You can feel that during shock servicing when sliding the rod assembly's piston and band through the stroke zone. Running the piston outside the majority stroke zone would have the fit tighten very noticeably.

    When I change the oil in modern, well anodized and hard coated shocks I am surprised at how not trashed from particulates the oil is. Sometimes the oil is surprisingly clean even after a ton of hard use, and the size increase is the stroke zone of the bore is very very small.
    #44
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  5. motobene

    motobene Motoing for 46 years

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    A bit of an alert here. Though I am finding in new bike setup a little more grease on the steering head bearings (but still not enough to reduce rust potential much), I am finding NO grease on Sherco-Scorpa suspension dog bones (they are just a little oily), and too little grease on the linkage rocker and swing arm pivot needle bearings.

    Also, the M8 bolt affixing the lower shock eye is bone dry and sometimes drooling-guerrilla tight. On the Scorpa 300 now undergoing setup, I just barely was able to POW! the bolt loose using every trick and caution available.

    Given there is no grease or anti-seize on the bolt, if left for years guerilla tight, well, good luck ever breaking that one free before destroying the hex socket!

    I strongly recommend early or earlier maintenance intervention on the rear end to keep the cursing and expense down later.

    Now Sherco-Scorpa use journal, not needle bearings on the dog bones. Journal bearings can bear extremely high loads because of high bearing interface surface contact area. But run dry, the surfaces adhere together and tear themselves up, microscopically. You've heard it, the creaky Shercos.

    There are also no seals on the dog bones. This can be bad, but also good. Bad at keeping water and dirt out, by also good because you can lube the dog bone bearings in a blink with squirts of oil that will wick right in on the spot, without disassembly.

    What I do is grease-pack mine in setup and about every year. In between it's the occasional squirt of oil on the bearing junctions. Overall there is no dry running, no creaking, and lifetime suspension bearings.
    #45
  6. motobene

    motobene Motoing for 46 years

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    The electrical system has changed on Sherco-Scorpa and the parts fiches have not caught up.

    There is a new (some time in the recent past) harness and new components for the fan circuit. On this new harness is a 24V 4700 mF capacitor on it's own connector, a 5A fuse in a protective holder, with an end in a CM1a-R-12V miniature fan relay that turns wiring back over the fuse holder to feed the fan.

    The capacitor I get. It can reduce the magnitude of fan rpm fluctuations with engine rpm changes. The fan will this do it's thing less 'snowflake whiney.'

    The addition of the fan relay I don't get, because the temp switch in the radiator has long had plenty of current capacity in and of itself (unless they have changed the guts to more delicate and temperature sensitive). Perhaps Sherco HAD to have one to comply with regulations that all fans must have relays?

    I'm guessing maybe the fuse is to protect the electrolytic capacitor from burning up if it fails? Don't know yet if the fuse precedes the capacitor yet because I haven't worked up an electrical diagram yet.
    #46
  7. Thesolidman1

    Thesolidman1 Adventurer

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    Ohlins is adamant that the shock is unrebuildable because that can only be done on one machine in Sweden that is slated only for production. To such trepidations I like to say simply, "Bullshit!"[/QUOTE]

    I have never read that Ohlins says their shock is not rebuildable. In fact, they are advertised as "fully rebuildable". At least on the SplatShop's website.
    #47
  8. motobene

    motobene Motoing for 46 years

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    Years ago I called Ohlins about a blown GG45 shock and initially got, "Sorry, unrebuildable, you have to buy a new one." After establishing technical rapport, I ended up with parts and their valve specs.

    The shock does have a gas port so it's rebuildable, though tricky due to the low oil volume. The Sherco Ohlins has even less working volume than GG45 and GG46 because the shock is shorter.

    I think the special machine in Sweden is for assembling the shock with no air. Randy Lewis says the machine makes a mess if oil in the working area.

    Perhaps similar to how shocks with blind bores and no gas valve or nut are assembled. The gas has to get pressurized to at or over 200 psi by forcing the separating piston to compress the gas via the oil.

    That's not how I'd rebuild one. I'd position the piston, then assemble the rod/piston assembly, carefully working the piston to bleed air. Then in goes the seal head, and out with the last few bubbles.

    The seal head o-ring will shut off the bore and pushing it in past the retaining ring groove will displace the separating piston a little deeper.

    The final step is charging and discharging the gas chamber a few times to take the trapped air from 78% nitrogen toward 100%, then a final bump to 220 psi or thereabouts. There may be a tiny bit of trapped air left doing it this way, but when internal pressure is bumped way up, the bubbles get either tiny or be pushed into solution with the oil.
    #48
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  9. motobene

    motobene Motoing for 46 years

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    Ever since my Android phone 'updated' to ignore USB cord file transfers, it's been no joy at photos edited and uploaded easily to Smugmug. I know, I need to get a file transfer app....
    #49
  10. motobene

    motobene Motoing for 46 years

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    Yup, I put a hole through the new front tube. It's now patched and got 3 oz. of Quadboss tire sealer. The rear got 4.

    It's bluish gray and has a nice consistency. We'll see if the stuff immediately seals the rear leak.
    #50
  11. motomaster132003

    motomaster132003 Adventurer

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    This is on a 2017 Scorpa 250 Factory, but this should apply to the Sherco Factory 250 as well. Is this breather intentionally sliced, or did the exhaust melt it? It looks more sliced to me. 20170524_101829_1495647880983_resized.jpg 20170524_102000_1495647881930_resized.jpg
    #51
  12. Limbman

    Limbman Adventurer

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    :roflThat might be an upgrade on the Factory

    Just kidding, there is no good reason, That I can think of to vent overflow fuel onto the side of the muffler...looks like a accidental slice to me.
    #52
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  13. Norman Foley

    Norman Foley Devotee of the Husqvarna

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    Same thing happened on '17 Scorpa 125SC. That is melted from the muffler. Guy told me his '15 Gas Gas quit and that vent line was melted shut by the muffler.
    #53
  14. motobene

    motobene Motoing for 46 years

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    Gosh, nice photos, Motomaster!

    You can see in the fine detail that the slice is cut, not melted.

    Present on all Keihins. The slice is intentional. It's to break syphon effect in the vent tube.

    Notice most Dell'Ortos don't even have vent tube anymore, for the same reason.
    #54
  15. motomaster132003

    motomaster132003 Adventurer

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    Interesting, doesn't that increase the chance of dust and water getting into the carb?
    #55
  16. motobene

    motobene Motoing for 46 years

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    So, I did a little more refinement in the jetting and thought I'd post a summary.

    Boyesen CarbonTech reeds (important mod for the 250, me thinks). Make sure to Emery-flatten the mating surfaces on the reed stops to get rid of the raised edges from the stamping die, else the CarbonTech reeds will stand off the reed block when you tighten the tiny reed screws.

    Main jet 120 (Sea level to 3,500 feet)
    Main jet 118 (3,500 to 5,500 feet)
    Main jet 115 (5,500 to 7,500 feet)
    Main jet 112 (7,500 and above)
    Low-speed jet 55 (All altitudes)
    Air screw 1-1/2 turns out as a baseline
    Needle clip Middle of 5 positions with the 55
    Float level 2 degrees toward lean
    Air filter soaked and squeezed out once with maxima FFT
    1/2 racing fuel 1/2 E10 regular/Maxima Formula K2 80:1
    Map set to sunny (always)

    Here is a photo from last year's 2016 Factory 250 after jetting and set-up for event one at Sipapu Ski Area, NM. The jetting specs are written on the float bowl, MJ, PJ, and clip position. The bike was just awesome! I just put a 55 in the 2017, getting it ready for its first event, once again at Sipapu:



    Stock, my bike, was:
    Sherco glass composite reeds (good reeds)
    Main jet 125 (fat)
    Low-speed jet 42 (anemic - ridiculous!)
    Air screw 1/16 turn out (because of the ridiculous jet)
    Needle clip in 2nd slot up from the bottom
    Float level 4 degrees toward lean (that was a surprise)
    Air filter lightly oiled
    1/2 racing fuel 1/2 E10 regular/Maxima Formula K2 80:1
    Map set to sunny

    Learned in today's jetting tests:
    - There was a little 4 stroking low load, low-, while slide backing off during a putt-putt test, so I wanted to see what would happen if I put the need clip two slots up in the 2nd position down from the top (leaner). To my surprise, I could make the motor bog opening the throttle moderately fast! And this bike comes with a 42 low-speed jet! To get bogging with only a 2-slot change in the needle is telling, like maybe the bike is 'asking for' a 55, or the 52 needs the needle clip in the stock position.

    I had a 55 in my `16, and it was just fantastic overall in smoothness and power. It will take more test iterations to determine if I will settle on the 52 or the 55.

    Answer! The '16 with spark arrestor liked a 55. My '17 with spark arrestor likes a 52. Every bike is an individual.

    Your results may vary according to fuel, altitude, riding(throttle) style, and traction (load), and to a small extent, bike individuality.
    #56
  17. motobene

    motobene Motoing for 46 years

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    I suppose so, but it's not a statistically significant issue.

    That tube is in a somewhat protected area. Vents tend to puke out fuel more than suck anything in.
    #57
  18. motobene

    motobene Motoing for 46 years

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    Melting the tube is certainly possible, especially if one rides moderately a lot, then sets the muffler afire (and the burn is sustained) on long climbs or hard charging on the loop trail.
    #58
  19. motomaster132003

    motomaster132003 Adventurer

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    I was thinking about replacing it with a silicone vent tube. If i do, do I need to add in the slice?

    Thanks
    #59
  20. motobene

    motobene Motoing for 46 years

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    I'd add the slice, but make it tiny.
    #60