Re-jetting carbs...

Discussion in 'Old's Cool' started by Cache, Oct 5, 2004.

  1. Cache

    Cache Adventurer

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    I posted this to my Triumph forum. However, you folks may be experienced with this issue as well.

    I’m thinking about squeezing a few more ponies out of my ’97 Tiger. Last year I had the cylinder head ports cleaned up, polished, and matched the carbs to the head. She wants to breathe but is restricted by a blanking cap on the airbox. My question is this… Why do the manufactures restrict the air intake in the first place? Will it affect the drivability in varying altitudes if I open her up and re-jet? How does it affect the torque curve? Are the carbs designed to have that negative restrictive environment??
    By any chance, have any of you posed these questions to DynoJet or K&N, or questioned why they only offer a Stage 1 jet kit? Usually needles and jets are matched to ensure a smooth transition to WOT. What is the result to the off idle/midrange by merely upgrading to the 130 DynoJet while using the Stage 1’s needle? Any flat spots or rough running issues? How about that little orifice you need to drill out for the piston/diaphragm assembly, does that need further tweaking beyond what DynoJet recommends?

    I searched the forums regarding camshaft swaps but could not find anything. I swear that I read somewhere guys were swapping Daytona cams into the Tiger engines, or at least suggesting this. Would the pistons and igniter need to be changed/upgraded as well? Is this really worth it? Has anyone here gone this far? I’m looking for 15-20 HP.

    Cheers
    #1
  2. creeper

    creeper Still alive...

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    By my count, ten questions in one post... that may be a record. Judges? :nod
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  3. Cache

    Cache Adventurer

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    :lol3 Ya, well smartie pants... You got em answerz for a couple, I'll narrow it down! :ear
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  4. creeper

    creeper Still alive...

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    I can answer one question. The jetting specific questions however I cannot.

    The air box is designed to provide a pressure balance for the CV carbs to function properly. Also, probably the reason there is only a stage 1 kit from Dynojet.
    A stage two kit, to be a viable deal, would require extensive carb & air box mods and would start approaching the price of slide carbs.
    I would imagine Dynojet saw no, or at best, a very limited market (crazy Triumph owners like you, for example) for a stage two kit... so none exists.


    So there... you poopie head :D
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  5. creeper

    creeper Still alive...

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    Or... I might be completely full of it. :D
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  6. Cache

    Cache Adventurer

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    There must be a meathod to their madness. My Honda ATV had a restricted air intake at the snorkel. Of course, I couldn't resist, hogged er out and re-jetted. I've got it tuned pretty good now but do notice that it's not as forgiving at the varying altitude changes.

    I'm hoping for a scientific explanation to this practice, not just on the CV carbs, but in general. Maybe you could have a few beers and keep going. It sounds good so far!!!

    :lurk
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  7. creeper

    creeper Still alive...

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    I hate to throw fuel on the fire, but unless someone has already done the experimentation and dyno time to support the modifications... you will be the first.

    The last sentence of your first paragraph is an indication of what you will run into... but on a larger and more unforgiving scale.

    I know... I'm a buzz killer.

    Creep
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  8. Cache

    Cache Adventurer

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    Thanks Creep, I'll blame you when I finally decide to buy the new girlie Tiger just for the extra 20 HP I'm lookin for. :huh
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  9. creeper

    creeper Still alive...

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    I would :cry for you... but I have no idea what your talkiing about.

    Just get a nitrous kit and quitcherbitchin'.... :evil
    #9