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Thinking cap's needed

Discussion in 'Motorcycle Tech Talk' started by cowboy, May 16, 2010.

  1. cowboy

    cowboy Moderator Staff Member

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    My bro-in-law has a 95 in kit put in his 00 dyna along whith SE 203 cams & some head work done Not sure who did the heads they redid the CV carb , from idel to about 3k the bike backfires through both carb & pipe , he runs the 2 into 1 set up , before all this work was done there was never a miss of any kind & would top out at a little better then 120 , now tops out at 106 but get there real fast , don't know what jets where used or whos kit, do know it's not one ken's
    We did double check for any & all types of leaks IE carb/ exhaust :banghead:
    cowboy, May 16, 2010
    #1
  3. Tomflhrci98

    Tomflhrci98 Active Member

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    hmmm lots was done so its hard to know where to start. Its not that easy to check the cam timing is it? Or, go into the CV and see what was changed, such as, did they change the spring or drill out the slide etc, etc.

    How does it start and idle??
    Tomflhrci98, May 16, 2010
    #2
  4. Art_NJr

    Art_NJr New Member

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    Tom mentioned cam timing & that's certainly something to consider. But having done a lot of work with exhausts for a very long time, I know there's a major torque dip in the 2500 rpm range with a 2-1 & while you can't tune that dip out, you can smooth that range out a lot. If the cam timing is correct & isn't changing due to slop in the drive, I'd start all over with the carb. I haven't bought one of "kenfuzed"s kits, but in this situation I would. I like the design of the needle & the taper is crucial - especially in the off-idle to 3000 rpm range.

    What you see all the time on the dyno is a spike in the A/F ratio in the 2500 rpm range - the carb goes way lean & that's where the "carb farts" come from. Add a 2-1 pipe to the mix & it's even worse. Going up on the slow jet size turns the spike into a bump & while the "seat of the pants dyno" may say the problem's gone, it's not, you just drowned it. The proper carb needle, along with the slide working properly, addresses the problem instead of just the symptoms.
    Art_NJr, May 17, 2010
    #3
  5. cowboy

    cowboy Moderator Staff Member

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    Thank's , the bike has had the super trap on it since it was about 2 week's old , it takes about 5 min to warm up with the choke on full about half of that then open it about half way for the rest of the 5 min , then it's just the back fireing up to about 3k then smoothes out :confused:
    cowboy, May 17, 2010
    #4
  6. hotroadking

    hotroadking Super Moderator Staff Member

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    Sounds like the carb is improperly tuned

    Nothing is wrong with a 2-1 on a street bike they
    work really well.

    How many discs and is he running the end cap on the exhaust?
    What are the jets in the carb, needle etc.

    Start by removing the discs and end cap and put back on without
    the last cover plate that closes it off. See if opening up
    the exhaust helps.. MIght not have enough plates to run the
    closed end cap...
    hotroadking, May 17, 2010
    #5
  7. Art_NJr

    Art_NJr New Member

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    Sounds like it's running way lean on the low end. But I wouldn't just slap a larger slow jet in, I'd want to know what needle is in the carb & when in doubt, I'd just start all over. You can do some tuning with the # of discs on the SuperTrapp and/or run a couple different kinds of end-caps, but if the carb's not right, none of that is going to solve the problem.
    Art_NJr, May 17, 2010
    #6
  8. hotroadking

    hotroadking Super Moderator Staff Member

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    Like Art says
    whats in the kit

    Check Needle, pilot and main - report that back

    How many discs, open or closed end cap.
    hotroadking, May 17, 2010
    #7
  9. cowboy

    cowboy Moderator Staff Member

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    if I can get time this weekend to double check this work I will get back here & let ya'll know , the mech that did the work has been a HD wrench for many years , bro-in-law has know him for many a years as well & seen a lot of his engine work , he's on Vaction now took a couple of months off for a few different reasons but calls all the time
    cowboy, May 17, 2010
    #8

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