rebuilt honda cb350 v. carb help

Discussion in 'OT Driven' started by ih8mice, Apr 2, 2007.

  1. ih8mice

    ih8mice New Member

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    i just rebuilt a '72 honda cb350k4. re-assembled it this past weekend and when i attempted to start it...gas ran out of the overflow from one of the carbs. i did rebuild both carbs and i'm not sure if i assembled one of them incorrectly. any ideas on what would cause gas to just flow through the carb? it only pissed out when the starter was cranking? planning on pulling the carb and tearing it apart again. not really looking forward to it so figured i should check with teh experts first. :x:
     
  2. DamonS

    DamonS Flyin' High Again

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    sounds like you either have the float set incorrectly or possibly the shutoff valve that the float presses against isn't stopping the fuel.

    The CB used a brass float, and was seriously prone to getting fuel inside it which would cause that behavior. Might be worth having a second look just inside the bowl.
     
  3. ih8mice

    ih8mice New Member

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    just drop the bowl and take a look inside before pulling the whole carb off?
     
  4. DamonS

    DamonS Flyin' High Again

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    i'd say yes. drop off the bowl. pull the pin that holds in the float and give it a shake, if empty, you are fine.. if full, time for a new float.. Also make sure the shutoff valve isn't jammed.

    Oh. turn off the fuel first and empty the bowl before removal. :)
     
  5. DamonS

    DamonS Flyin' High Again

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    oh. and another thing...

    Make sure your float is adjusted correctly.

    You'll probably need to take the carb off for this step but basically to set the float properly on that bike, you turn the carb upside down and the arm on the float should be parallel to the carb casing
     
  6. ih8mice

    ih8mice New Member

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    good stuff...thanks for the help

    i'll be sure to respond with the outcome
     
  7. ih8mice

    ih8mice New Member

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    ended up trying to start the bike again last night and no fuel leakage from the carb this time. it still wouldn't start tho. checked plugs and points, both are firing. fuel is getting to the carb. it sounds like the engine has compression (felt airflow from the muffler)...it just cranks and cranks and doesn't seem like it's even close to firing up. i'm all out of ideas and don't feel like taking it to a shop and paying more than the bikes value fto have it diagnosed. any ideas/suggestions?













    buy a newer bike doesn't count, although that is steadily moving up the list.
     
  8. DamonS

    DamonS Flyin' High Again

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    Sounds like you may have the timing off. I believe the CB had a guage on the flywheel to indicate TDC and you can make sure the fire is happening at the right time. It was so easy to be 180 degrees off on those motors.

    If you have a good spark and the fuel is certainly getting to the cylinder then it could be timing. They were finicky.
     
  9. keleko

    keleko yes, he is

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  10. Toyman321

    Toyman321 New Member

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    I've got a CB500... carbs are simmilar so for the carb problem it could be a couple of things. The way the floats are setup if the floats drop too low they can actually push sideways on the needle of the valve and cause it to stick, eventually it works itself free but the problem may arise again.... just one other thing to look out for. I had a stuck float on one of my carbs, it seems to be a common problem with the cb's, which caused it to piss all over my garage.

    As far as it not starting, as above I'd guess the timing is out.

    Another forum to try to cb stuff is sohc4.net it's a dedicated forum for the single overhead cam bikes, although their is a "4" in the name, they've got a ton of 2cyl guys on there too.

    Good luck!
     
  11. Vermincelli

    Vermincelli Banned

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    GET OFF MY LAWN!
    I get to rebuild mine this weekend. Pulled them out of the bike last night. Thought of just dropping them off at the local shop to have them do it so I can go do other shit but they just laughed and said they won't touch anything older than 7 years. Good to know the local shop is a haven of idiots for thinking carb design has so radically changed in 7 years. Retards. So much for spending the day at the range.
     
  12. noxxs

    noxxs New Member

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    as much as i love working on bikes, carbs are by far the most annoying. it takes so much time to put them in and take them out to diagnose whatever problem you're having. very frustrating.
     
  13. keleko

    keleko yes, he is

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    i gave up on mine :(

    http://forums.offtopic.com/showthread.php?t=3152032
     
  14. noxxs

    noxxs New Member

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    i did the same thing with my first bike. i honestly, without exageration, had the carbs on and off that bike over 50 times trying to get it running. it was probably more my fault than the bikes as i didnt know much about it. it was a good learning experience though, it ended up being the pilot jet was clogged and thats why i couldnt get it running. i bought the bike for $60 at an auction and sold it for $1000. i had about that much in parts in it though and it was still iffy on when it wanted to run.
     
  15. keleko

    keleko yes, he is

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    if i hadn't done anything it would still be running - but rough on idle, and leaking gas like a sieve in the tube between 1st and 2nd carb - so they HAD to come off
     
  16. Vermincelli

    Vermincelli Banned

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    I tore mine apart yesterday and back in the bike this morning. Primary jet was just filled with sludge on one and the float was stuck on the other one. Used a Clymer manual since no one has info on a 1980 anymore. Didn't bother with rebuild kits since 95% of the time they aren't needed anyways. Just took them apart one at a time and dunked them in Gunk for 30 minutes. Then used a toothbrush to go over everything and then an air compressor to dry everything out. rubbed some oil on the seals to let them soak it up and reseat themselves and bike's running like a champ. Not bad considering the bike's been sitting in the shed for over 10 years. Had to dump the gastank and dunk the petcock but after it sat in some oil to reseat those seals it's no longer leaking.

    Next I have to replace both sprockets and chain, new set of tires and swapping out the buckhorn handlebars with a set of sportbike or Daytona bars.


    I found that a good little trick before you go tearing into the carbs is to take a camera and take a ton of up close pics. Then take pics as you tear them apart. If you run across something that you aren't sure of and the manual doesn't go into detail on, go back to the pics as reference. (I do this for everything actually)
     
    Last edited: Apr 16, 2007

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