LC4e hiccup

Discussion in 'Thumpers' started by sss, Feb 5, 2006.

  1. potatoho

    potatoho Cheese and Rice!

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    I definitely meant only the four stroke flange at the midpipe to silencer connection. The header flange, no way. I think the temps between a two stroke pipe flange and a four stroke silencer flange are probably within 100 degrees of one another. The silicone tape has a 500*F rating which is similar to ultra copper, but the tape has a bit more strength. It has a tendency to unravel or snap on the last winding. I still have to perform a post mortem on a recent failure on the two stroke however due to some mud puddles and hard running. It ran good for a few weeks, and it was my first attempt so it is probably something obvious. It's nice to be able to wrap it up and go without waiting two days for the ultra copper to dry.
    #21
  2. meat popsicle

    meat popsicle Ignostic

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    Remember those are rough guidelines, and I can think of a few variables that will influence which jets will work best with your bike; so I can't imagine anyone would say that your main jet is TOO large for your bike at those altitudes (period).

    Of course one of those know-it-alls could come along at any moment and... :doh

    What I would like to see are more diagnostic tools for deciding which jet selections are working and which are not working. I have read, for example, that if you bike does not require any choke (enricher?) to start that the main jet might be larger than it needs to be. I have also read that slightly leaner pilot jet can improve the instantaneous throttle response. Those types of diagnostic observations are very helpful IMhO.

    Anyone? :deal

    BTW, these Supertrapp IDS2 documents may help your tuning of the muffler:

    http://www.powroll.com/PDF/INSTRUCTIONS/EXHAUST/SUPERTRAPPIDS2 INSTRUCTIONS.pdf

    http://www.supertrapp.com/images/pdfs/003-2296.pdf
    #22
  3. creeper

    creeper Still alive...

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    This thread is so convoluted, with all the quotes and quotes with quotes, that after the first few posts I can’t even begin to figure out what’s what... what 'zactly are the core issues here anywho? :dunno
    #23
  4. sss

    sss paid to worry

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    I am trying to adjust the air/fuel mixture using write-ups by both you (Creeper) and Flanny. The main jet is 157.5, the muffler is an IDS2 with quiet core (maybe quiet core), the air box is not modified except for the KTM side screen. The bike is a 640 lc4-e.

    I ride between 5500 and 10,000' elevation. All adjustments are at 5500'. The bike is fully warmed up.

    Per Flanny, I adjust the air mixture until the engine speed drops (3 turns out). Then I adjust in the other direction until the engine speed drops (6+ turns out). Per Flanny this would indicate the need for a larger main jet. Per Creeper's guide I already have a main jet size more appropriate for sea level.

    Am I heading in the right direction if I start testing larger main jets or is there possibly something else going on that needs to be addressed first?

    Thanks for your help.

    Steve
    #24
  5. creeper

    creeper Still alive...

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    Hey Steve... thanks for the clarification. Now I know whats what. :D

    The screw really only works within a 3 turn from seated range... beyond that, the orifice is wide open and you’re spinning your wheels.
    The setting for most bikes jetted properly is usually somewhere between 1.5 and 2.5 turns out from seated. Personally, I run 1.5 turns out at sea level and 1 turn out at elevations above 6K feet.

    If your pilot circuit is too rich, you can screw the needle all the way in almost and the bike will continue to run... when in fact it should die about 1/2 to 1/4 turn from seated if you're jetted correctly.
    If it's jetted too lean, you may have to turn it out 3 turns for the bike to idle OK... and it still may not enough.

    In is lean, out is rich. Don't assign to much fuel delivery value to the mixture screw... your jetting has to be pretty close to correct for it to offer any useful tuning function.
    The mixture screw tends to work best when you are no more than one pilot fuel jet size, or one pilot air jet size rich or lean from a theoretical "perfect".

    This might help 'esplain things.

    [​IMG]

    Got it? If you have any other questions... you know where to find me. :wink:
    #25