Ktm 125 sx not reaching powerband?
  • fchabrafchabra
    Posts: 20
    My 2003 ktm 125 sx that I bought two months ago won't reach high rpms. It will lug around fine in the low end of a gear. When I rev the bike it will sound like it is sucking power away. It idles and revs awesome in neutral, but when you gas it in gear the bike will not go any faster and you will have to shift up. My old cr 85 had more top end then this bike. Do any of you think it might be the power valve?
    1991 Yamaha Blaster
    1999 KX 250
    1994 KDX 200
    2006 KX250f
  • NZriderNZrider
    Posts: 5,090
    I think it might be the power valve. have you checked its operation?
    *********************
    Winning is 90% rider and only 5% bike, the rest is luck
  • PaulB14PaulB14
    Posts: 8,012
    I had the exact same problem with my Honda CR250: I checked everything! Turns out that the silencer was plugged up with carbon/oil. With a new silencer the power problem went away...
    ///////////////////
    NW Montana - Where the pavement ends and the fun begins
    image

    2005 KTM 300exc
    1977 SUZUKI PE250
  • BleedMarshallBleedMarshall
    Posts: 2,572
    I would check the carb as well. May be clogged up in the jets and such. However, did it run fine before and this is a recent issue to crop up, or has it always run like this?
    --------------------

    2006 YZ125
    2006 300 XC-W
    "I do dumb things."
    "God hates a coward."
    "I may not always know, but I'll find the answer."
    http://www.facebook.com/dirtbikesrock
    http://dirthammers.com/
    http://ryandhackney.wordpress.com/
    https://twitter.com/RyanDHackney
    image
  • fchabrafchabra
    Posts: 20
    I took the silencer apart today and found that the packing was ripped and was soaked in oil. I will buy new packing tomorrow and see how that turns out. And yes I cleaned the carb, I replaced the main and pilot jets back to stock procircuit size about a month ago. When I bought it, I rode it in the guy's backyard trails, but they were too skinny for me to go fast and reach powerband in them. I didn't know about the issue until i brought it home 2 months ago.
    1991 Yamaha Blaster
    1999 KX 250
    1994 KDX 200
    2006 KX250f
  • BleedMarshallBleedMarshall
    Posts: 2,572
    If the packing was toast, as you say, that had a lot to do with it if not the whole issue. Packing is cheap a around $7 USD plus shipping. Keep us posted on how it goes.
    --------------------

    2006 YZ125
    2006 300 XC-W
    "I do dumb things."
    "God hates a coward."
    "I may not always know, but I'll find the answer."
    http://www.facebook.com/dirtbikesrock
    http://dirthammers.com/
    http://ryandhackney.wordpress.com/
    https://twitter.com/RyanDHackney
    image
  • fchabrafchabra
    Posts: 20
    Packing it did help a little, but its still not reaching its full potential. I also noticed that the clutch isn't operating smoothly as well. When I try to start the bike in gear with the clutch in, it takes like 15 kicks compared to starting first kick in neutral. The bike also jolts forward when i kick it in gear with the clutch in.
    1991 Yamaha Blaster
    1999 KX 250
    1994 KDX 200
    2006 KX250f
  • BleedMarshallBleedMarshall
    Posts: 2,572
    If the bike moves when started and the clutch pulled, you need to look at your clutch. Plates may be worn as well as the basket. You may just need the cable adjusted, but usually it is the clutch itself.
    --------------------

    2006 YZ125
    2006 300 XC-W
    "I do dumb things."
    "God hates a coward."
    "I may not always know, but I'll find the answer."
    http://www.facebook.com/dirtbikesrock
    http://dirthammers.com/
    http://ryandhackney.wordpress.com/
    https://twitter.com/RyanDHackney
    image
  • fchabrafchabra
    Posts: 20
    Well I brought it up to the shop and they said that it only had 50 lbs of compression!!!! The normal for a 125 sx is around 150 lbs. The guy who i bought it off of said that it had a brand new top end, but i guess you can't trust everybody. I'm getting new rings and a new piston. Hopefully that will fix the issue. The shop manager also said that the powervalve was fine.
    1991 Yamaha Blaster
    1999 KX 250
    1994 KDX 200
    2006 KX250f
  • PaulB14PaulB14
    Posts: 8,012
    glad you got it figured out!
    ///////////////////
    NW Montana - Where the pavement ends and the fun begins
    image

    2005 KTM 300exc
    1977 SUZUKI PE250
  • BleedMarshallBleedMarshall
    Posts: 2,572
    Good deal. Sad you have to pay labor prices, but good deal of getting it sussed out.
    --------------------

    2006 YZ125
    2006 300 XC-W
    "I do dumb things."
    "God hates a coward."
    "I may not always know, but I'll find the answer."
    http://www.facebook.com/dirtbikesrock
    http://dirthammers.com/
    http://ryandhackney.wordpress.com/
    https://twitter.com/RyanDHackney
    image
  • Maple Leaf MXMaple Leaf MX
    Posts: 12,825
    sussed = bleedmarshalls most overused word
    Expect to die whenever but dream to live forever

    ..the good times on the old DR board will never be back! RIP!
  • NZriderNZrider
    Posts: 5,090
    Well 2 months ago it may have had a new top end, its possible it got damaged in that time. good luck on the rebuild though. it will be great to have all the power back.
    *********************
    Winning is 90% rider and only 5% bike, the rest is luck
  • BleedMarshallBleedMarshall
    Posts: 2,572
    Maple Leaf MXsussed = bleedmarshalls most overused word
    Wrong! The word "however" is used far more often.
    --------------------

    2006 YZ125
    2006 300 XC-W
    "I do dumb things."
    "God hates a coward."
    "I may not always know, but I'll find the answer."
    http://www.facebook.com/dirtbikesrock
    http://dirthammers.com/
    http://ryandhackney.wordpress.com/
    https://twitter.com/RyanDHackney
    image
  • Maple Leaf MXMaple Leaf MX
    Posts: 12,825
    honky tonk badonkadonk!!
    Expect to die whenever but dream to live forever

    ..the good times on the old DR board will never be back! RIP!
  • BleedMarshallBleedMarshall
    Posts: 2,572
    You sir must listen to Trace Adkins.
    --------------------

    2006 YZ125
    2006 300 XC-W
    "I do dumb things."
    "God hates a coward."
    "I may not always know, but I'll find the answer."
    http://www.facebook.com/dirtbikesrock
    http://dirthammers.com/
    http://ryandhackney.wordpress.com/
    https://twitter.com/RyanDHackney
    image
  • fchabrafchabra
    Posts: 20
    Alright, I got my ktm back from the shop today. The shop manager took it for a test drive. He said that it ran the balls, so right when I got it off the truck, I went riding. Bike ran great. It was ready to even race. But 10 minutes later it *** out on me again while going through some water about a foot and a half high (I doubt water got in the silencer, but a possibility since i have a procircuit shorty). It didn't stall or anything, I didn't kill it, it was running the entire time. It just unexpectedly started to act exactly how it was before I brought it to the shop. Dramatically lower pitch, won't hit powerband anymore, and will die if you don't give it more throttle after you really gas it. I will read you the entire list of parts the shop put on.
    1 CHAIN, SUNSTAR
    1 CABLE/THROTTLE KTM
    1 KTM CLUTCH MASTER CYLINDER 10.5
    1 FILTER, AIR KTM
    1 PISTON KIT SX125-EXC
    1 GASKET SET TOP END KTM 125
    1 NGK SPARK PLUG
    NEW COOLANT
    NEW CLUTCH FLUID
    1 GRIP, KEVLAR
    What they did:
    REMOVE TOP END FOUND WORN PISTON, REPLACE PISTON AND RINGS, AND ALL TOP END GASKETS. CLEAN AND LUBE POWER VALVES. REPLACE AIR FILTER. REPLACE SPARK PLUG. REPLACE THROTTLE CABLE. REPLACE CLUTCH MASTER. TEST RIDE WAS OK.
    Parts Subtotal: $425.60
    Labor Subtotal: #240.00
    With tax and other charges, the total came out to $696.91. Money is very hard to come by, seeing as I am only 15, and I can't afford another bill. I literally spend all my money on this. How can I fix this?
    1991 Yamaha Blaster
    1999 KX 250
    1994 KDX 200
    2006 KX250f
  • BleedMarshallBleedMarshall
    Posts: 2,572
    It was just rebuilt, so I hope you broke it in before you went and rode at any considerable time and speed. It should take you the better part of a day to break a bike in properly. If you did not do that, then you may have just done some damage.

    I would first check the plug to see what it looks like. It is probably loading up from the oil used to wet the parts on rebuild. If it is black, change the plug and see what happens.

    Keep us posted and we will help you as best we can.
    --------------------

    2006 YZ125
    2006 300 XC-W
    "I do dumb things."
    "God hates a coward."
    "I may not always know, but I'll find the answer."
    http://www.facebook.com/dirtbikesrock
    http://dirthammers.com/
    http://ryandhackney.wordpress.com/
    https://twitter.com/RyanDHackney
    image
  • fchabrafchabra
    Posts: 20
    When the shop owner called my dad and said that the bike was ready and that he had already test driven it, I assumed that it had already been broken in since he had rode it. I guess that it wasn't. If the new piston and rings weren't broken in properly, would it be safe to say that I need another set of rings? I'm not exactly familiar with this kind of stuff. I will check the plug tomorrow and see what it looks like.

    Oh and guy who did the work wasn't in today so I couldn't talk to him, but I talked to another employee and I told him that the bike had a lot of spooge coming out of the silencer and where the silencer meets the expansion chamber. He told me to run a different type of oil since I was running redline synthetic snowmobile oil. I cleaned the exhaust out repacked the silencer, drained the gas, and put in a 30:1 ratio of super with golden spectro and there hasn't been any spooge coming out since. The bike still runs terrible though. I will post again tomorrow since that's my day off from work.
    1991 Yamaha Blaster
    1999 KX 250
    1994 KDX 200
    2006 KX250f
  • Valentin424Valentin424
    Posts: 148
    For future reference it takes about 3 tanks of gas to break it in and yuh want to run alot more oil in your mix while breaking it in (I dont remember the exact amount) and its best to run 32:1 once you have broke it in.
    I just got done breaking in my bike.
    ****************************************
    ALWAYS check your brakes BEFORE the race
    (Lesson learned the hard way)

    Valentin
    424

    1998 Kx 125 - My Baby
    1993 Kx 250 - Dads monster
    1973 Kd 175 - Old School Swag
  • fchabrafchabra
    Posts: 20
    Yup, I thought that the shop broke it in but I'm not sure if they did or not because I can't call them since they're closed this weekend. I checked the plug and it was fine. It was brand new anyway. I am running 30:1 with golden spectro. The bike is running pretty bad right now so I'm not sure if I should continue to ride it around for a little while longer around my yard and let it go through some more gas and oil or if I should just leave it and let the shop take care of it. If its in this condition, is there anything I can do to help it without taking the motor apart?
    1991 Yamaha Blaster
    1999 KX 250
    1994 KDX 200
    2006 KX250f
  • NZriderNZrider
    Posts: 5,090
    "running in" on a 2 stroke top end rebuild is a HIGHLY over rated procedure. the only aspect that needs "running in" is the ring to cylinder seal, rings are round, cylinder should be round if its still good, they should be good to race pretty much from the moment they're assembled, my top ends get about 5 minutes of gentle warming up then i ride them like normal. i use 32:1 oil same as always and have never had a problem with ring failure as a result.

    did you try a new plug yet? strip and clean the carb? what have you checked so far?
    *********************
    Winning is 90% rider and only 5% bike, the rest is luck
  • fchabrafchabra
    Posts: 20
    The plug wasn't the problem. It was replaced along with the piston and rings, but I took it out and cleaned it off with a rag anyway.. The thing that I'm confused about is how the top end only lasted for around 8 minutes. Would this be an error on the shop's end? The owner took it out for a ride and said it was fine and then when I rode it it died without me even reaching 3rd gear. Would this be my fault or the shop's?
    1991 Yamaha Blaster
    1999 KX 250
    1994 KDX 200
    2006 KX250f
  • NZriderNZrider
    Posts: 5,090
    have you checked the top end? i think it will be fine. theres another issue here thats being missed. i would think its more than likely an ignition problem if the carb is fine.
    *********************
    Winning is 90% rider and only 5% bike, the rest is luck
  • BleedMarshallBleedMarshall
    Posts: 2,572
    It very well could be an ignition issue. Get out the multi meter and check your connections from the wiring harness out to the components. If your plug is not getting the proper "juice", it will not operate correctly.
    --------------------

    2006 YZ125
    2006 300 XC-W
    "I do dumb things."
    "God hates a coward."
    "I may not always know, but I'll find the answer."
    http://www.facebook.com/dirtbikesrock
    http://dirthammers.com/
    http://ryandhackney.wordpress.com/
    https://twitter.com/RyanDHackney
    image
  • fchabrafchabra
    Posts: 20
    I brought it up to the shop again and they told me it was a loose bolt in the powervalve that kind of messed everything up, so they tightened it back up and hopefully it will run better when I get it back today. That would explain why it would kind of sputter when I was in high rpms when I was test riding it, and then just not hit at all.
    1991 Yamaha Blaster
    1999 KX 250
    1994 KDX 200
    2006 KX250f
  • PaulB14PaulB14
    Posts: 8,012
    The first time you took it in, the shop manager told you the power valve was fine. Now they say the power valve has a loose bolt. I'm beginning to have trust issues with the shop manager....
    ///////////////////
    NW Montana - Where the pavement ends and the fun begins
    image

    2005 KTM 300exc
    1977 SUZUKI PE250
  • BleedMarshallBleedMarshall
    Posts: 2,572
    Bad shops give good shops a bad name. As PaulB14 stated, the guy said one thing and then said the opposite. I know of shady shop tactics to do certain things so you have to keep coming back, and this is along those lines. I would maybe try a different shop, or buy tools and fix the bike myself. Easy to do if you have the manual, and the tools pay for themselves.
    --------------------

    2006 YZ125
    2006 300 XC-W
    "I do dumb things."
    "God hates a coward."
    "I may not always know, but I'll find the answer."
    http://www.facebook.com/dirtbikesrock
    http://dirthammers.com/
    http://ryandhackney.wordpress.com/
    https://twitter.com/RyanDHackney
    image
  • fchabrafchabra
    Posts: 20
    Paul, you might be right. Some of my friends swear by the place, but others hate it. I will probably order a manuel off the internet. I have to do a top end rebuild soon on my blaster anyway, so I'll order one for that too.
    But the bike runs awesome now. It actually hits powerband and I took it to a track Saturday. I have a couple of videos if anyone wants to see them. I appreciate all the help everyone.
    1991 Yamaha Blaster
    1999 KX 250
    1994 KDX 200
    2006 KX250f
  • BleedMarshallBleedMarshall
    Posts: 2,572
    Good deal. Post up the vids when you can.
    --------------------

    2006 YZ125
    2006 300 XC-W
    "I do dumb things."
    "God hates a coward."
    "I may not always know, but I'll find the answer."
    http://www.facebook.com/dirtbikesrock
    http://dirthammers.com/
    http://ryandhackney.wordpress.com/
    https://twitter.com/RyanDHackney
    image
  • garrisson09
    Posts: 7
    fchabraPacking it did help a little, but its still not reaching its full potential. I also noticed that the clutch isn't operating smoothly as well. When I try to start the bike in gear with the clutch in, it takes like 15 kicks compared to starting first kick in neutral. The bike also jolts forward when i kick it in gear with the clutch in.
    My ktm 125 sx does that too im not positive but i think its because of the hydraulic clutch they have its diferent then capble clutch



    TTr 125
    CR 250
    Ktm 125 sx
    summit 600
    polaris indy 440
    \and more
  • Cr131
    Posts: 7
    I have a 2006 ktm 125 recently had a full engine rebuild carb and plug Is fine very good spark but has no power at all, it's slower than a dt125 any help would be much appreciated
  • NZriderNZrider
    Posts: 5,090
    well something is wrong so dont assume anything. recheck the compression. verfiy the power valve operation. check jetting is factory or very close too it. verify ignition timing. check the reeds are ok
    *********************
    Winning is 90% rider and only 5% bike, the rest is luck
  • Cr131
    Posts: 7
    Ok thanks mate will check all this today the bike was fine before I got it rebuilt but it was stood for a year with a seized engine?
  • NZriderNZrider
    Posts: 5,090
    oh and one more thing, check the exhaust isnt blocked
    *********************
    Winning is 90% rider and only 5% bike, the rest is luck
  • Cr131
    Posts: 7
    Yeah I got told it could be the silencer or power valve
  • BleedMarshallBleedMarshall
    Posts: 2,572
    Siezed engine? Do a good check on that cylinder. I have seen siezed engine look good, but mic out as bad.
    --------------------

    2006 YZ125
    2006 300 XC-W
    "I do dumb things."
    "God hates a coward."
    "I may not always know, but I'll find the answer."
    http://www.facebook.com/dirtbikesrock
    http://dirthammers.com/
    http://ryandhackney.wordpress.com/
    https://twitter.com/RyanDHackney
    image
  • Cr131
    Posts: 7
    The bottom end went over a year ago but it's been stood for 12 months like it and I've just had a full rebuild?
  • NZriderNZrider
    Posts: 5,090
    so what have you actually checked so far?
    *********************
    Winning is 90% rider and only 5% bike, the rest is luck
  • sean
    Posts: 3,724
    Take it back man
  • yuzhao88
    Posts: 7
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