Engine Revs Unstable

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by Pedro Nelson, May 6, 2006.

  1. Pedro Nelson

    Pedro Nelson Brazilian KTM Pilot

    Joined:
    Nov 11, 2005
    Oddometer:
    11
    Yesterday I start felling that when the engine temperature reach 102 ° and the radiator fan starts the engine revs go up at least 500 rpm and keeps at this level for a good period of time

    I have tried to understand what is happening and went to the local KTM dealer but they said that this is the first time that they are facing such kind of problem.

    I also noted that engine revs are not so stable and fall from 1500 rpm to around 1200 rpm and came back to 1500 rpm.

    Please could anyone give an idea what is happening with my KTM 950 ADV .

    Kind Regards

    Pedro Nelson
    #1
  2. coyote

    coyote gagger of lollies

    Joined:
    Dec 5, 2003
    Oddometer:
    27,493
    Location:
    mom's basement
    Mine did this before I removed the EVAP system.
    #2
  3. La_Poderosa_3

    La_Poderosa_3 It's not freezing!!!!

    Joined:
    Jan 17, 2006
    Oddometer:
    164
    Location:
    Tiburon, CA
    How many miles are on your bike?

    I have found mine used to stray quite a bit (between 1400 and 2000). But once I had the first service done, evap can out, and a few thousand more miles on it has steadied itself out a bit but still strays between 1400-1750 or so.

    I wouldn't worry about it too much, other than you don't want it to idle under 1400 or oil won't make it into the head.

    I would take the bike out for a ride and get it really warmed up, then use the idle screw and put the idle more or less where you want it and then forget about it.

    #3
  4. KTMlvr

    KTMlvr Adventurer

    Joined:
    Jan 9, 2006
    Oddometer:
    25
    Its funny that this thread has started, i came on here to search for the same thing and saw this. My 04 S is doing that hot and to fix it from FUCKING STALLING at the traffic light. I cranked up the idle to 1500 and its better but still will shut down when the rpm dips too far down.. Im not very impressed with this as its a very very expensive bike and the carb work is that of somthing worn out.. Im pissed, then on the other hand once rolling along its fine.. wrap it up to 7-8 grand and hold on.. its a riot..
    #4
  5. La_Poderosa_3

    La_Poderosa_3 It's not freezing!!!!

    Joined:
    Jan 17, 2006
    Oddometer:
    164
    Location:
    Tiburon, CA
    Like I mentioned earlier, 1500 is really the minimum you should idle the bike. Any lower than that and it won't pump oil into the head.

    The next remedy is to pull the evap can. Additionally, last week, some fellas here were talking about a "cannisterectomy lite", in which you pull the drain plug on the hose that drans the cannister and find that its all jammed up with necrotic gas.

    http://www.advrider.com/forums/showthread.php?t=94545&highlight=canisterectomy+lite


    If you try this I bet you might like it. However, be sure to keep your idle up, you think your bike is expensive now, rebuilding the head or getting a new engine ain't gonna be pretty.

    #5
  6. Freddie Rides

    Freddie Rides Can't find the door

    Joined:
    Jan 23, 2005
    Oddometer:
    244
    Location:
    Denver-ish
    Mine does the same thing . . . and it's the clutch. You'll notice that when the rpms drop if you let off the brake the bike wants to pull forward. It's almost like the gears are engaging on their own.

    So the new question is: Why does the clutch vary pressure all on its own?

    Maybe ought to read up on clutch slave cylinder problem.
    #6
  7. TipOver

    TipOver Been here awhile

    Joined:
    Jan 11, 2006
    Oddometer:
    405
    Location:
    Boise, Idaho
    Pedro, your details are a bit scanty but if the engine is hot (fan running) and you are moving slowly or even stopped then the bike is breathing that hot air from the engine (through the horn on the airbox). That WILL cause a change in idle.

    I suspect that hot, thin air will cause your engine to run rich (thin air, same fuel) & that may cause an increase in idle.

    Solution-Don't get stuck in traffic. :D These engines do require moving air across the radiators to cool them. And keep the previous suggestions you've received in mind as they are valid as well. Good Riding.
    #7
  8. gefr

    gefr Life is a trip

    Joined:
    Nov 26, 2005
    Oddometer:
    4,558
    Location:
    East Med, Greece
    The instability of rpms I have, I was told was due to worn carbs??? at 54 k kms!! The clutch dagging is a different matter!! The factory asks for 1400 rpms idle!! Cheers!!
    #8
  9. idahoskiguy

    idahoskiguy Long timer

    Joined:
    Jun 22, 2005
    Oddometer:
    1,144
    The EVAP theory has merit, my 06 exhibits this beheavor but I realy never considered it a problem and it has never stalled. Just keep the idle at 1400 as per the manual and you should not have any trouble.

    Also if you have overfilled the fuel tanks you may have gotten fuel in the canister (EVAP) and this could make the problem worse. Should correct itself as the fuel in the canister is used up and you don't over fill the tanks.
    #9
  10. BOB RAMSAY

    BOB RAMSAY Not in the Clique -

    Joined:
    Jul 11, 2011
    Oddometer:
    444
    Location:
    Granville, Ohio
    I see this is an old thread. Here's my take (2012). When the idle allows the bike to stall, I turn up the (remote) idle adjustment. Then, the rpm's will run too high. I have found that when I re-fuel at the end of the day, my problem seems to go away for the next ride. I'm guessing poor fuel quality, which is a pretty reasonable guess I think. Works for me! Good luck. *(cheap fix)
    #10