KTM 950SM 2-1 exhaust

Discussion in 'Road Warriors' started by wsdbikes, Oct 12, 2007.

  1. montibank

    montibank Happy

    Joined:
    Feb 7, 2007
    Oddometer:
    3,072
    Location:
    Fresno, Ca
    Hah nice ... The trick is going to be finding a liter bike with a USFS stamp on it and something not too obnoxiously loud.
    #21
  2. montibank

    montibank Happy

    Joined:
    Feb 7, 2007
    Oddometer:
    3,072
    Location:
    Fresno, Ca
    Well crap. Figured I would tear bike down to start fixing it. Pulled filters off... Started bike, covered front carb, bike shut down immediately. Covered rear carb... Bike runs. What? Little/no change... Uh oh. Try again... Same. Really make a good seal with my hand... Bike chugs right along. Shit ... Soo that is why I couldnt turn the idle up any more... It was already in all the way and running on one cyclinder.

    Shit... I think I just bought a lemon. Crap crap crap.

    Soo just to verify... I unplug rear cyclinder spark plug boot. Bike runs ... Just like normal.

    Damn shoulda test rode one before so I knew what kinda power to expect. Damn.
    #22
  3. BuddingGeezer

    BuddingGeezer Been here awhile

    Joined:
    Aug 17, 2009
    Oddometer:
    233
    Location:
    Benton, AR
    Pilot screws control air or fuel depending on the location on the carb. If the screw is between the intake manifold and throttle butterfly they control fuel. Screwing them in reduces the fuel making the mixture leaner. If the screw is between the carb's mouth and throttle butterfly it controls air, screwing it in reduces air making the mixture richer.
    #23
  4. renogeorge

    renogeorge Let's ride!!

    Joined:
    Apr 7, 2007
    Oddometer:
    2,266
    Location:
    Reno
    So. Check the obvious things related to the rear cyl. Spark plug? Coil/cap tight? Check carb for blocked jets--start with idle jet. Is the idle adjustment screw linkage OK? Adjustment screws are fuel screws--in means less fuel and leaner. Out for more fuel--richer.

    Good luck
    #24
  5. montibank

    montibank Happy

    Joined:
    Feb 7, 2007
    Oddometer:
    3,072
    Location:
    Fresno, Ca
    Ya trying the simplest first, or so I thought. Cant get the rear plug out none of my sockets are thin walled enough. No one local sells thin walled sockets, in fact I got a lot of blank stares and "huh" from all the local auto places I called. Spent the last two hours trying to sand down one enough... No luck there.

    Looks like this isnt gonna git fixed anytime soon.
    #25
  6. renogeorge

    renogeorge Let's ride!!

    Joined:
    Apr 7, 2007
    Oddometer:
    2,266
    Location:
    Reno
    With motor running, did rear cyl carb slide open when you cracked the throttle? Might want to check the diaphram for a hole/tear...
    #26
  7. montibank

    montibank Happy

    Joined:
    Feb 7, 2007
    Oddometer:
    3,072
    Location:
    Fresno, Ca
    Ooooh kay... So got it pulled apart some... Rear valves are just tight... All of em. Like well under min spec.

    So simple fix... Valves balance carbs and I should be back in business.

    Resume original hijack ...

    Liter bike exhaust can suggestions?
    #27
  8. montibank

    montibank Happy

    Joined:
    Feb 7, 2007
    Oddometer:
    3,072
    Location:
    Fresno, Ca
    Yep. And I checked the boot its in good shape.
    #28
  9. montibank

    montibank Happy

    Joined:
    Feb 7, 2007
    Oddometer:
    3,072
    Location:
    Fresno, Ca
    #29
  10. slackmeyer

    slackmeyer Don't mean sheeit. .

    Joined:
    Jul 23, 2007
    Oddometer:
    3,626
    Location:
    Berzerkeley, CA
    Don't worry, orange crush will come to you.

    First, the pipe is not your problem right now. Make the bike run on both cylinders before you get worried about the FMF on one side not flowing enough, the FMF works fine there, I had one on a 2-1 for 25,000 miles before a friend gave me an akra that he had extra from his 2-1 conversion. I don't have any problem power wheelieing in the first two gears, and in the third with a slight rise.
    If I were you, I'd start where I would with any new-to-me bike: adjust the valves, really thoroughly clean the carbs and write down all jets and settings, change the oil, change the sparkplugs, change/clean the airfilter. It's a fair bit of work, but less than chasing your tail trying to find a problem. Stock jets with the needle raised one clip and no prefilter work very well on this bike if your carbs are clean, I'd start there before you modify, or start near there
    Stock:
    157.5 front main, 162.5 rear, 42 pilot jet, fuel screws 2.25 turns out, floats set at 3-3.5mm down from gasket surface, idle air jet #50 (I think, this is from memory, maybe double check at ktm950.info). Needle clip at 2nd slot from top (non-pointy) end stock, I recommend moving it to 3rd.

    My jetting is exactly the same except I have 165 main jets now, I thought the stock jetting got a bit lean on the top end. I have been through H2W jetting and a few other configurations, These were ok, but I prefer what I have now- best power everywhere, IMHO. I may shim the needles to end up between 2nd and 3rd clips, since fuel mileage is a concern for me, and I seem to be getting mid 30s right now, would always like to get a bit more range from my tank. . . .

    By the way, inspect the carb diaphragms very carefully, and try switching the stick-coils that go on the spark plug, see if you can get the back cylinder to fire. It's probably not the valves, though the valves might make it run not quite as good as it could.
    #30
  11. montibank

    montibank Happy

    Joined:
    Feb 7, 2007
    Oddometer:
    3,072
    Location:
    Fresno, Ca
    Valves have already been brought back into spec they were very badly out (tight)

    Firing on both cylinders.

    Filters cleaned

    New plugs - went with the iridium just cause they were in stock and the standards werent at the local auto place.

    Carbs clean.

    Has the head 2 wind jet kit now...

    Pilot screws @ 1.75 turns out

    Clip in third position

    Still no wheelie goodness.

    Good to know that yours would wheelie on the 2-1 with the single without using the clutch and a single fmf exhaust can. That is what I really needed to know. Confirms my suspicions that something is up with power delivery
    #31
  12. wsdbikes

    wsdbikes New Max is Mad

    Joined:
    May 8, 2007
    Oddometer:
    1,282
    Location:
    PNW
    from what i understand based on previous research and info the H2W kit was the bomb for the adventure. I think having the prefilter on was required for the jetting to be right unless you asked to have it jetted specifically without it.

    The fact that it runs that poorly before you started may mean you have some other issue.

    my SM was a 2006 and the stock cans were de catted and the jetting was pretty much spot on for them and it ran excellent before i started the 2-1 project.
    I used a Yosh can from a gsxr1100 to ensure I had enough flow. it was less restrictive than the two stock cans even after the de cat.
    It really freed up some ponies in the mid range.
    I regret not doing a dyno before and after but, other crap got in the way.
    i still miss that bike.

    I would just start from scratch and go step by step to determine the root cause of the poor running. comp check, coil check, etc.

    good luck

    #32