Carburetor settings - EZ90

Discussion in 'Tech Area' started by walbright, Aug 13, 2019.

  1. walbright

    walbright New Member

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    I'm new to this forum and am trying to get a 1993 Honda Cub EZ90 running again after it has sat idle for several years. We've had the carburetor off and thoroughly cleaned it. Flushed the gas tank and put in new gas. Sucked out the injector oil and filled with new Honda GN2 injector oil. Unfortunately, we can't get it to run. The only way we've been able to get it to start is if I "manually" choke it by putting my fingers over the intake. If I remove my fingers, it dies. It doesn't seem to matter what I do with adjusting the jets. Any ideas on what is going on here? Thanks.
     
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  3. OLD CT

    OLD CT Well-Known Member

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    Did you remove both of the jets and the main jet holder to clean the emulsion tube?
     
  4. walbright

    walbright New Member

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    I wish I were more of a mechanic! We did remove the two jets and cleaned them. We also removed the adjustment "screws" and cleaned them. I don't know what the emulsion tube is.
     
  5. OLD CT

    OLD CT Well-Known Member

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    emulsion tube.jpg I am not familiar with the EZ90 but do remove the carb and bowl to post a pic of the jets. The emulsion tube on a CT70 4 stroke is the brass hex nut that the main jet goes in.

    The emulsion tube is on the far right. It has a bunch of tiny holes in the side that need to be rodded out with something the size of a 'bread tie' wire, after you remove the paper or plastic off it.
     
    #4 OLD CT, Aug 13, 2019
    Last edited: Aug 13, 2019
    Anthony Campano likes this.
  6. Anthony Campano

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    Hi I wish old ct lived in the north east I’m in ri. He knows his bikes
     
  7. walbright

    walbright New Member

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    Thanks for your comments. As soon as I get a chance to pull that carburetor off, I'll post some pictures for you to review.
     
  8. Anthony Campano

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    Thx I’ll wait for your picture of the carburetor thank you Anthony.
     
  9. walbright

    walbright New Member

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    I finally got time to get back to the EZ90. I pulled the carburetor off again... took it apart... and here are some pictures. One think I noticed as I was taking a closer look at the jets is that the "larger jet" (the lower one in the picture below) has an opening through the middle of it, lengthwise. However, the smaller jet (the upper one in the photo) looks like it should be open through the middle of it also, but I can't get my little wire to go through it and I can't see any light through it either. Should there be a hole through the length of the jet?
    carb pic4.jpg carb pic4.jpg carb pic6.jpg carb pic5.jpg carb pic4.jpg carb pic3.jpg carb pic2.jpg carb pic1.jpg
     
  10. OLD CT

    OLD CT Well-Known Member

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    Nice, now remove the main jet holder. It's the brass hex nut under the main jet that is on the ''bottom'' in the pic. Clean all the holes on the side of it. Pull the pilot jet above the main jet and check it out and clean it again. All the holes in the side of it and make sure you see light thru it.
     
  11. kirrbby

    kirrbby Well-Known Member

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    That pilot jet hole is probably super small. I had a carb from a ST50 that I had to use a tiny brass wire from a toothbrush type wire brush. A regular wire brush wire was too big.
     
  12. walbright

    walbright New Member

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    I used a "high E string" from my guitar and was able to get the hole through the small jet open. Made sure both jets are clean. The Emulsion tube is open. So far as I can tell, the carburetor is good and clean. Put everything back together and it still only runs if I put my fingers over the intake to reduce the amount of air it gets. If I remove my fingers, it dies. What do you think is going on here?
     
  13. OLD CT

    OLD CT Well-Known Member

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    Possible air leak.
     
  14. walbright

    walbright New Member

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    Here are some pictures of the carburetor installed. From your experience, where should I be looking for an air leak? There is the black insert between the carburetor and the intake to the cylinder with "o-ring" type gaskets on both sides. The two bolts that attach the carburetor pass through it. With the o-ring gaskets, I think it should be pretty tight. Any advice would be appreciated. carb pic8.jpg carb pic7.jpg
     
  15. dirtbkr188

    dirtbkr188 Active Member

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    There appears to be two paper gaskets (parts #5 and #11, below) on either side of the reed cage, they could be a possible air leak area. Did you check the condition of the reeds themselves?

    RvrRy1.png
     
  16. walbright

    walbright New Member

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    No. We've never removed part #18 in the drawing. Regarding the condition of the reeds, what should I be looking for?
     
  17. walbright

    walbright New Member

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    I guess #18 is actually the o-ring. But we've never removed the part "above" the reed cage.
     
  18. dirtbkr188

    dirtbkr188 Active Member

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    You'll want to make sure there are no cracks or missing pieces (if they are fiberglass or carbon fiber). I'm not sure what the reed petals are made of from the factory, or if the petals are replacable in your particular case. They are not shown separately in the above diagram, like they are in the 1993 CR125R diagram HERE
     
  19. dirtbkr188

    dirtbkr188 Active Member

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    Boyeson does make replacement reeds for your bike, as seen HERE, if you need them.
     
  20. OLD CT

    OLD CT Well-Known Member

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    The oem reed petals are usually stainless steel. They need to sit flush with the cage. They do wear out, get bent enough to hang open a little.

    If there is one thing that made a difference with any 2 stroke I owned, changing out the OEM petals to Boyeson reed petals. Then you tweak the petal stoppers to open up a little more as seen in the directions, made the bike run great. Spray around with a can of carb spray and listen for a change in the rpms.

    Something else to check, the air/fuel screw is set at least to the ''initial'' setting, 1 1/2 turns out and not screwed all the way in.
     
    #19 OLD CT, Aug 28, 2019
    Last edited: Aug 28, 2019

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