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Help MC22 not starting

Discussion in 'Honda 250cc In-line 4's' started by markcm02, Oct 9, 2021.

  1. markcm02

    markcm02 Member

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    Hey guys,

    So I've picked up this bike as a project and it's been great fun wrenching on it however I have hit a roadblock.
    When I purchased the bike, the seller showed me it running off a fuel line straight to the rails at the carbs, however when he applied throttle the bike boggs and dies leading me to believe a carb clean was in order.
    I have come around to cleaning the carbs and inspected the jets and saw they were clogged and so I did a full clean of the carbs. Now I have rebuilt the carbs, adjusting the fuel screw to 2-1/2 turns out on all carbs, reassembled the air box and fed it fuel through a hose straight to the to carbs. I have tried with the vacuum line for the fuel petcock plugged and un plugged. The bike cranks but no get up. I have checked sparks on all plugs and they are bright blue, when I pulled them out they did smell like they had fuel on them so I really have no idea what the issue is here. Any help or ideas is greatly appreciated.
    Cheers.
     
  2. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    I'm not familiar with MC22 carbs, but what exactly did you do when you cleaned them? If you only pulled out and cleaned the jets, there are many small orifices and passageways in the carb bodies that must also be clean and free of debris or blockages.

    Given the fuel on the plugs, they are either fuel fouled or the bike is flooding. It can be common for float needles and seats to not do their job properly after being removed and refitted. Check each of the floats carefully. Many times I have found a stuck needle that required a little persuasion by operating the float manually to unstick the needle and ensure it is seating properly. They get stuck open (jammed) and the float won't move.
     
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  3. markcm02

    markcm02 Member

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    I used an ultrasonic cleaner on my carbs and it looks like it did a really good job, I couldn't find any dirt after the cleaning. I checked all floats were bouncy before sealing them up and even had them inspected by a guy from the auto arts store who also said they were good, but still couldn't tell me why the bike didn't start. It is possible that the float needles get stuck even after inspection, just seems like such a small window. I have cleaned the plugs since pulling them and haven't yet pulled them back out to check the presence of fuel. I am really just clueless at this point on what to do, I will pull the carbs back apart and tripple check float needles. Thanks for your resposne :)
     
  4. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    Does it fire on starting fluid?
     
  5. markcm02

    markcm02 Member

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    Actually come to think of it I did get some life out of it when I was spraying carby cleaner, so the issue is must be fuel, I just have no idea what down the line is wrong, nor how to test components indavidually.
     
  6. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    Remove the tank, block the vacuum line and use a bottle and some fuel line to see if it runs that way.

    If it does I would suspect a blocked or broken fuel tap. Worth checking the inside of the tank for rust and debris as well.

    The fuel tap strainers can also get blocked up from debris.
     
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  7. markcm02

    markcm02 Member

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    The only way I have been trying to run the bike is through your mentioned method, I am holding off assembling it any further until I get it running.
     
  8. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    Hmm, okay.

    Try draining the bowls on the carbs as they are and see what comes out.

    I would also set the float heights again.

    Is the battery in good condition? Have you got a charger or jump start pack?
     
  9. kiffsta

    kiffsta Administrator Staff Member Contributing Member Dirty Wheel Club

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    What year Mc22 , the earlier l and n models should be set to 1 and 5/8 turns, the latter r models are 2 and 1/8 turns out

    the Mc22 does not have adjustable floats

    Plugs do not clean very well, grab 4x cr9eh-9 plugs, these bikes need a good strong battery to start. I’d grab your multi meter and check your coil leads, stick your meter on kilo ohms, test cap1 and cap4, you should get 23-32 k ohms , also check 2 and 3 for the same result

    if you need help, give me a call , I am in Capalaba
     
  10. markcm02

    markcm02 Member

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    I have drained the bowls and the fuel comes out looking the same as when it went in, not sure what else I’d be looking for.

    I have never set the float heights and I wouldn’t know how to either, I can’t see any point of adjustability.

    The batteries are good, I’ve drained the first one from cranking so I’ve got it charging whilst I’ve hooked up a battery from my other bike. I’ve heard the spark unit won’t spark the plugs if the battery isn’t high enough voltage so I think battery isn’t the issue.
     
  11. markcm02

    markcm02 Member

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    not sure the exact year of bike, from the stamping of what I understand is the import plate, it was imported in ‘98

    The plugs looked like they haven’t had much use I’ll take a pic when I get home, but I’ve got 4x cr9eh plugs is there a difference between them and the -9 plugs?

    For testing the coil leads, would I be putting it in resistance mode and grounding them while the bike is off or measuring resistance between the coil leads?

    I am quite of ideas so if I can’t fix it tonight I’ll give you a call tomorrow, I’m up in Brendale/strathpine area.
     
  12. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    Hmm... are you using the choke? If not, try that. If you have, try without and try a little bit of throttle.
     
  13. markcm02

    markcm02 Member

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    i have been trying with choke as that’s what the seller advised I do for a cold start, I will try without choke and with a bit of throttle and update thread in about 10mins
     
  14. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Compression test.
     
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  15. markcm02

    markcm02 Member

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    Sounds expensive :(
     
  16. markcm02

    markcm02 Member

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    Tried starting without choke and varying levels of throttle, still nothing. What’s the average time to be holding the starter waiting for something to happen, currently I’m just doing 2-3 seconds.
     
  17. kiffsta

    kiffsta Administrator Staff Member Contributing Member Dirty Wheel Club

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    1990-93 are the 45 hp versions, the 94-99 are 40hp

    if you look at your cdi, if it says kaz - 45 hp, if it says kazg -40 hp model.

    Your carbs are also stamped near the bowl lip on the front, vp20a is 45hp, vp20b is 40hp

    With your coils, put meter on kilo ohms, put one lead up the plug cap of cylinder 1 and the other prong up the cap of cylinder 4 , do the same for 2 and 3 , a lot of people accidentally pull the leads instead of the caps and yiu can have no / bad spark issues

    Another check is the pickup coil , it is the yellow / white wires which plug into the harness under the air box, do an ohms test, should between 330-430 ohms

    If you are pulling the carbs off, pull your air fuel mix screws out, you should see a spring, metal washer and rubber washer , this is key to getting them to start, I have seen so many of them missing a washer or 2 , if they are all there, wind then in until they seat, then back them out to the correct setting for your year

    I’d do a compression test, if it is okay, then stick 4 new plugs in
     
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  18. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Engines require compression, spark & fuel.
    To start a 30 year old motorcycle of dubious history I would begin with:
    1/ a compression check, if good then proceed to the next step otherwise I wouldn't waste another second.
    2/ Then check the leads, caps and test the spark with new plugs, if good then proceed to the next step
    3/ Check you have clean fuel being supplied to the carbs
    4/ Crank with full choke and no throttle
    It should catch almost immediately.
    If you keep cranking then you will flood it.

    Note that the standard batteries on these little bikes are very small and the spark is weak whilst cranking. They usually catch when you take your finger off the button because the coils can finally deliver a healthy spark.
     
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  19. markcm02

    markcm02 Member

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    Ok weird, my CDI is stamped KAZG but the carbs say 20 A B G H with a square around the B. Could this discrepancy be cause of my issue?

    I’ll test coils and pickup now, if they seem fine I’ll swap plugs, if not plugs I’ll pull carbs and inspect screws and then finally if still no start I’ll talk to some people about borrowing a compression test kit because I don’t have one of my own.
     
  20. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    Sounds like it has 40HP carbs and ignition
     
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