help please
  • goodie209
    Posts: 32
    mind you the compression feels week with the hand and I compared to another 125 and it's about half of that. So I have a 1990 Cr125r I replaced the piston, ring and gaskets. The bike started on the 5th kick I let it run for a couple min. Then shut it off. Then It kicked over the first time. It didn't have much fuel in it and it high Reved it's self when it ran out. Now it won't start at all I ripped the head off and every thing seemed fine cleaned the carb and all it does is backfire while kicking over at full throttle. My friends and I think it's the ring ideas are greatly welcomed
  • BleedMarshallBleedMarshall
    Posts: 2,600
    What is your ring gap, and is it in spec.?
    --------------------

    2006 YZ125
    2006 300 XC-W
    "I do dumb things."
    "God hates a coward."
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  • sean
    Posts: 4,125
    Try to put few drops of oil in spark plug hole,see what it does
    image
  • sean
    Posts: 4,125
    High rev is common when running out of gas at a idle
    image
  • gearman
    Posts: 121
    If the compression still low after piston/ring replacement, the cylinder may be worn out and bike will not start.
  • goodie209
    Posts: 32
    I tried oil in the cylinder and it backfired first kick and nothing after that
  • goodie209
    Posts: 32
    Now IM waiting on a ring and hope it's a fix I will update thanks
  • markyrocks
    Posts: 1,353
    I'm with gearman. I think ur cylinder needs attention, they don't last forever. If u just rebuilt it running it out of gas ain't gona make ring go bad. Running it with no oil in the fuel would do it. Don't forget the piston and ring arnt only things responsible for compression. If ur spark plug isn't tight, or cylinder top isn't on tight could cause a loss.

    With out a compression tester there no way to actually know what ur psi is, I'm almost wondering if u didn't suck a bunch of crap into ur Carb when u ran bike dry.
    As a side note why does nobody have a compression tester? Dear Gawd you'll spend money on bikes an parts but not the number one tool to check the condition of the most important part of the whole bike.
  • CRWOODS
    Posts: 477
    did you try a new plug?
  • goodie209
    Posts: 32
    Naw the cylinders fine it was looked at by a cycle shop. Do you think because it was 40/1 instead of 32/1 fuel it could have hurt it?
  • goodie209
    Posts: 32
    No on the plug it's new I don't think it would foul off the first Start would it, it looked fine had a lot of gas in the cylinder like it was flooding out but I cleaned the plug
  • CRWOODS
    Posts: 477
    Use a new plug so you can rule that out. A cleaned plug won't always work.
  • goodie209
    Posts: 32
    I'll get another one do I think a 9 is to hot cuz that's what I had that's what the book called for and the fuel I ran 40/1 instead of 32/1 on start up do you think that was a bad move aswell?
  • CRWOODS
    Posts: 477
    Should use 32:1 on new top end, but 40:1 is not a big difference and should not have hurt anything, but running dry/lean ain't great for it. A 9 is not gonna be too hot I would not be afraid to use an 8
  • goodie209
    Posts: 32
    Well I will give it a shot and see what happens. Thank you for the advice. What should my compression be and how do I check it. I mean how many kicks for an accurate reading?
  • BleedMarshallBleedMarshall
    Posts: 2,600
    Compression test is three kicks, minimum, with throttle wide open. To get a bas reading of what psi you need to be at you take your compression ratio from your manual, which should be around 8.5:1 - 10.5:1, and multiply those numbers by 14.7. Follow?
    --------------------

    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
  • goodie209
    Posts: 32
    Yeah so 125-155 should be my compression?
  • goodie209
    Posts: 32
    Right?
  • BleedMarshallBleedMarshall
    Posts: 2,600

    You used my numbers I gave you, so maybe. I was guessing at what the compression ratios would be and I have no true knowledge of what your compression ratios would be. I did a quick Google search and found an 8.9:1 compression ration for your bike, so your reading would be more like 130-135, which is about right for most 125s of that era.

    --------------------

    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
  • goodie209
    Posts: 32
    Ok cool thank you that does sound about right
  • goodie209
    Posts: 32
    Does anyone know with a 90 exhaust expansion pipe what years are comparable with it?
  • goodie209
    Posts: 32
    Is a 93 compatible
  • goodie209
    Posts: 32
    ok so i have replaced the pulg fixed the carb leak it has good compression and tryed push starting the damn thing and it still wont start. what the hell am i missing?
  • goodie209
    Posts: 32

    will reeds cause a starting issue. i can see day light through 2 but not that bad. i have new gas 32:1  i dunno what to do, advice please?


     

  • markyrocks
    Posts: 1,353
    Clogged exhaust/muffler packing?
  • goodie209
    Posts: 32
    It's not connected the exhaust I have isn't the right one it came from a Cr80 so to small but the springs hold it up
  • Mark47mxMark47mx
    Posts: 1,905
    Reeds will cause difficult starting  if you can see between the reed and the cage you need to replace them
    with the new plug I'm assuming you checked for spark.

    Tap on the carb bowl you may have a stuck float
    Also to get fresh fuel in the bowl lean to bike over and hold the throttle full open until you see fuel come out the vent tube.

    I would recommend putting the correct exhaust on
    .
    .
    Colorado

    2006 RM-250
  • gearman
    Posts: 121
    Check spark again if OK, then check the pilot jet for clog.
  • daggitdaggit
    Posts: 9,524
    Did you clean the filter?
    Never Too Old
  • goodie209
    Posts: 32
    Ok so I have a new bike a 94 rm125 I've been looking at namura pistons does anyone have an opinion about them or what piston to use? I was told not to use quarto in an rm because of the slip in warm up will seize the motor! So namura or pro x piston all opinions welcomed thanks
  • goodie209
    Posts: 32
    Not to use wiseco*
  • goodie209
    Posts: 32
    Stupid spell check. I was told it's because of the slop it has when it's cold.
  • NZriderNZrider
    Posts: 5,154
    forged pistons like wiseco are fine to use in your bike as long as you warm your bike up properly before riding it hard. namura products seem to be fine. i've used them in a few different things with good results
    *********************
    Winning is 90% rider and only 5% bike, the rest is luck
  • goodie209
    Posts: 32
    I've heard about them exploding but as runability there sick and also the skirts break
  • NZriderNZrider
    Posts: 5,154
    then make your own decision.
    *********************
    Winning is 90% rider and only 5% bike, the rest is luck
  • goodie209
    Posts: 32
    I've been trying to lol
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