Spark Arrestor Solutions

Discussion in 'Trials' started by motobene, May 23, 2017.

  1. motobene

    motobene Motoing for 46 years

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    Here is the part, assembled. IMG_20170530_173828184.jpg
    #41
  2. VxZeroKnots

    VxZeroKnots Long timer

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    Sorry to clutter the thread with ramblings from a simpleton, but aside from the lack of beautiful machining, what are the disadvantages to the setup I have? Is it too restrictive?
    [​IMG]
    My bike was occasionally doing some weird stuff at idle at Sipapu, it felt like it wanted to stall. That being said I have no idea what jets are in it, and I've only had it 3 days at this point. Power felt fine everywhere other than going up some of the ski runs but I attributed that to a gappy transmission more than jetting. I'm curious to hear your thoughts.
    #42
  3. lineaway

    lineaway Long timer

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    Lean on the pilot and rich on the main. Read Bene's jetting suggestions.
    #43
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  4. motobene

    motobene Motoing for 46 years

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    Also, as you go up in altitude, idle will drop. Sipapu has a rare significant altitude change within a single event.

    I failed to run an over-high idle at the bottom of the hill and got myself two stall fives on sections at the top of the hill Sunday (plus my 250s carb is acting inconsistently).
    #44
  5. VxZeroKnots

    VxZeroKnots Long timer

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    Thanks for the pointers. Carry on.
    #45
  6. motobene

    motobene Motoing for 46 years

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    The spark arrestor setups on the two 2017s worked flawlessly at the Sipapu events.
    #46
  7. Yard Sale

    Yard Sale Long timer

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    I just bought a 2017 Gas Gas 250 and I'm baffled (ha!) by how difficult it is to get a spark arrestor on it and be legal. Can someone suggest how I can go about doing it?

    I ordered an exhaust adapter and Spanish Fly screen arrestor, but only received the latter. I don't think the supplier is going to come through soon with the adapter.
    #47
  8. Yard Sale

    Yard Sale Long timer

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    Wanna take bets on how long before this falls off?

    [​IMG][​IMG]

    The set screw is just kissing the end of the pipe, so I used a bunch of high-temp sealant to fix it in place, with a safety wire tether.
    #48
  9. 10K

    10K Trail Runner

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    28 minutes, what do I win?
    #49
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  10. Yard Sale

    Yard Sale Long timer

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    Ha! It stayed on for nearly two hours!

    [​IMG]

    I had to pull it off when my bike stalled and wouldn't restart. I thought it was clogged.
    #50
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  11. kenny robert

    kenny robert Been here awhile

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    a 2 stroke with an exhaust system that is quite long like every 2 cycle motorcycle ever made cannot produce a red hot spark out the tailpipe anyway
    the whole shitty deal is based on an old chainsaw with an extremely short path from exhaust port
    #51
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  12. motobene

    motobene Motoing for 46 years

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    Whatever works!

    The silicone solution will last as long as Mr. Fly doesn't get whacked from a side or end fall, which could be the life of the bike under a more skilled rider that crashes infrequently. RTV silicone cred is good for about 600 degrees F.

    If it does get knocked off you can just adhere it on again. With a tether it's no worries, mate!
    #52
  13. DualSpaz

    DualSpaz Been here awhile

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    Not true. I let a friend ride my 2003 GG280 Pro on a short trail ride, I followed behind on my wife's CRF230, we had done maybe 3 or 4 miles and were back on the road headed home when I got close I could see the red hot sparks coming out of the tail pipe. After being ridden at 1/2 to full throttle for 15 minutes or so the exhaust got hot enough that the carbon build up on the spark arrester screen was flaking off and producing the glowing sparks. The bike was very hot, but not "boiling over" hot. I will say that the bike was jetted way rich, had just moved from NJ (sea level) to NM(7000' +). And trials bikes get very hot when ridden at a trail bike pace. Probably an unlikely scenario for most, but possible. Also I learned how important it is, not just to have a spark arrester, but to clean it regularly.
    #53
  14. lineaway

    lineaway Long timer

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    Yes, the s/a screen caused the carbon build up and the restricted flow contributed to the overheating. Just like catylitic converters causings fires in tall dry grass.
    #54