Rally engine's & exhaust systems

Discussion in 'Racing' started by Mudguts, Jul 18, 2014.

  1. Mudguts

    Mudguts when in doubt GAS IT

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    Ok we have the Nav tower thread , the ICO thread so here's the engine thread
    For tips and rebuild tricks

    So my set up is this

    KTM 690. (654cc) bone stock :rofl:rofl: well motor has not been molested as yet
    Vortex X10 programable ignition
    Andrea Dionda Rally exhaust 50mm through to 60mm at muffler link pipe
    Muffler Akro rally. 60mm taper core down to 50 mm at exit

    So my bike goes Ok but I also know that the exhaust is to big for my current set up . Im in planing of building a big bore engine in other words saving $$$$ for the parts

    1) 2012 stroker crank
    2) port & polish head
    3) Cam stock ,Rally , DukeR ????
    For the piston there are a few chooses
    Stock 102mm 11.8:1 Compression Ratio
    Hi Comp 102 12.5:1 CR
    Then I can go 103 ,104,105mm piston , but may have to swap over to carb'd and $$$$.

    I'm leaning towards stock size piston for ease of sourcing and reliability but also want a torque monster that can wheel stand at 100kph in 4th
    #1
  2. Mad Cow

    Mad Cow Dakar Addict!

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    I'm of the opposite opinion, go standard for maximum parts availability.

    My 450 has an entirely standard engine.....

    Including a "standard" 525 barrel and piston :D
    #2
  3. michael1968

    michael1968 Long timer

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    Stick size piston is good because you don't need to worry about getting your barrel bored out and the potential issues associated with that (sleeves failing, cooling etc.).

    You probably know but you don't want to polish your intake ports, the slightly rough surface keep your fuel from forming big drops.

    Another good few hp out of a 690 and you'll have a real weapon!
    #3
  4. Mudguts

    Mudguts when in doubt GAS IT

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    Defiantly new more torque to lug my fat ass around , but had a win out playing with the fuel trims on Saturday
    #4
  5. Mudguts

    Mudguts when in doubt GAS IT

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    Just had Crazy idea of a twin cam head for the 690 I think it would be a good way to throw away $$$$$$$$ .
    #5
  6. craigincali

    craigincali Just hanging around

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    if you want to spend cash I will give you my paypal account and you can put it in there.
    #6
  7. JMo (& piglet)

    JMo (& piglet) Gone a bit Baja

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    Rally Raid Products have just introduced a hi-comp piston for the stock bore... that would be a good place to start?

    Jx
    #7
  8. Mudguts

    Mudguts when in doubt GAS IT

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    I'm keeping an eye on john's and martins FB web sites just in case they post some dyno runs with the new pistons
    #8
  9. JMo (& piglet)

    JMo (& piglet) Gone a bit Baja

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    I'll mention it to them - I know that Martin has his own 'demo' 690 EVO2 set up now, so perhaps the new HC piston will find its way in there soon!

    Jx
    #9
  10. Seth S

    Seth S Will _____ for _____

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    Ditch the cams and go with solenoids
    #10
  11. Mudguts

    Mudguts when in doubt GAS IT

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    Trying to keep the electrical simple :D
    #11
  12. Seth S

    Seth S Will _____ for _____

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    Well lets see..

    My current engine is running stock rods with offset bushed flat top vw piston. The 16v head is fitted with double valve springs, rally cams, solid lifters, and bigger volvo valves. Alumiunum flywheel at the moment and likely a quartermaster clutch. Header is a 4 into 2 into 1 header. Custom ITB intake and T5 fuel injection. Possibly an electric water pump and more compact denso alternator.
    #12
  13. Mudguts

    Mudguts when in doubt GAS IT

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    And it's got four wheels Pppfft , traction junkie :D
    #13
  14. JayBo1

    JayBo1 Long timer

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    Yeah, but does it's wheels fit between the rails of a stock grate?:lol3
    #14
  15. Seth S

    Seth S Will _____ for _____

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    Not when it's airborne
    #15
  16. Mudguts

    Mudguts when in doubt GAS IT

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    #16
  17. Mudguts

    Mudguts when in doubt GAS IT

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    My build has started via ordering the 2012 stroker crank :D
    And while the crank in out the head will go on the flow branch then will be port and polished.

    I have not decided what to do with the piston , if the cylinder is good the hi comp 102mm 13:1 rally raid piston will go in , if bad it will be bored out and a 104mm 12.5:1 piston will go in.

    Kinda hoping foe the 104mm piston :D:D:D
    #17