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ktm 625 smc issues

Discussion in 'Mechanical & Technical' started by ZXWUT?, Aug 13, 2012.

  1. Just finished recently with a fresh rebuild on a 2005 KTM 625 SMC. It's all back together and been working on tuning.

    Starting off, it ran terribly. The most noticeable was that it felt like it was cutting out at a steady throttle. Wide open felt fine. It would also die at an idle.

    Yesterday, I pulled the jets, cleaned them, and the pilot was partially clogged. As of right now, here is how it sits:
    -Blue needle, third clip from top
    -170 main
    -45 pilot
    -Mixture screw 1.5 turns out

    When it was first started, it ran great at idle! Then as it warmed up, the rpm's started to bump up to 2500-3000rpm's, then back to normal idle. It did that several times. It is still doing the thing where it feels like it is hiccuping, but barely noticeable. Before, it would feel like it was going to throw me into the handle bars, then yank me back when it picked up again. It is also backfiring like a mofo on decel.

    I've been screwing with it for quite some time now and have reached the end of my knowledge. I'm lost. Any ideas?

    Edit: Forgot to mention, I tried to adjust the idle to 1500 rpm's after I set up the pilot circuit, and it is very hard to turn. I had to use a pair of pliers. It also doesn't appear to change anything when I turn it either direction.
  2. RedKat600

    RedKat600 Vintage Screwball Staff Member

    Lean condition so....either you have a vacuum leak (carb boot to cylinder head leak?) OR your pilot circuit is still dirty. Not the jet itself, but the circuit in the carb. Remove the A/F screw and make sure the o-ring is in good shape and the circuit is clean.

    Don't those have a TPS also? I know those are finicky on KTM's....might be worth a look.

    Last but not least, how are the valve clearances?

  3. Boots are like new, but I will spray some starting fluid around them just to be 100% sure they aren't leaking. A/F screw is brand new, as is the o-ring. I just pulled and checked it last night when I cleaned the jets.

    It does have a TPS, and I'm thinking about disconnecting it to see what happens. The valve clearances were set about 100 miles ago.
  4. RedKat600

    RedKat600 Vintage Screwball Staff Member

    Is the old o-ring for the A/F screw still in the hole though? That's happened to me before...just a thought.

    Another though....recheck your cam timing if you just rebuilt it. Might be a tooth off.....
  5. Already double checked timing and the old o-ring is out. I think I might pull the carb yet again and blow out all of the passages
    Posted via PNW Riders Mobile
  6. RedKat600

    RedKat600 Vintage Screwball Staff Member

    If you're going to pull it again, dip it if you can. That way you won't have to question it and can move on to other things!
  7. Lean in the idle circuit
    If the idle rises when's lean
    You're only out a turn and a half.
    Go some more and see if it gets better
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