Where should I start jetting this?
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  1. #1
    Senior Member KTMATVHQ Member
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    Nov 2010
    Location
    Maryland
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    297

    Where should I start jetting this?

    Hey everyone, I'm getting ready to start this engine up for the first time. Sent it out to CT Racing and had maintenance and all that done (hone, new gears, timing chain, rod, piston, bearings) and I'm not sure where to start the jetting at. The carb is stock except the fastranchero mods. With the engine stock, I was running a 170 main, 42 pilot, 55 leak jet, HRC needle on the 2nd clip, and fuel screw 1.75 turns out.

    Build: 450cc 12.5:1 Compression, web cam (not sure which one he put in), +1 exhaust and intake valves, race port and polish, has a full Yoshimura exhaust.

    Any recommendations? Thanks.
    '09 KTM 450XC. CT Racing built JE 12.5:1 compression, port and polish, Web cam, +1 valves, Hot Rods con-rod, Yoshimura exhaust, removed t-stat coolant hoses, JB Racing Pro Advance A-arms, re-valved Ohlins shocks, Lonestar axle, all the good stuff

  2. #2
    Super Moderator KTMATVHQ Addict
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    Apr 2013
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    New Mexico
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    519
    I'd say you are not too far off right there, maybe go about 2.5 turns out on the A/F screw.

  3. #3
    Senior Member KTMATVHQ Member
    Join Date
    Nov 2010
    Location
    Maryland
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    297
    Cool, I'll try it out. I mainly stay close to sea level also.
    '09 KTM 450XC. CT Racing built JE 12.5:1 compression, port and polish, Web cam, +1 valves, Hot Rods con-rod, Yoshimura exhaust, removed t-stat coolant hoses, JB Racing Pro Advance A-arms, re-valved Ohlins shocks, Lonestar axle, all the good stuff

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  5. #4
    Member Rookie
    Join Date
    Jan 2014
    Posts
    40
    I would agree with Kmack try to turn the a/f mixture 2.5 turns and see how the engine would behave. If that doesn't work get a stage 1 jetting kit and just follow the instructions.


 

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