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  1. #1
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    Join Date
    Sep 2009
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    318

    Default 72 CB350 fuel delivery/carb problem

    I have this 72 CB 350 that I bought at the beginning of summer. Compression on both cylinders is around 170. Points are set properly. Iím having some type of fuel delivery/carburetor issue. I put on brand new petcock, new in-line fuel filters and cleaned the carbs. When I turn the fuel on I only get a trickle in one of the fuel filters coming from the dual lines in the petcock. I was under the assumption that the carbs create a vacuum and will pull fuel into the float bowls but I think I'm wrong. When I ride the bike I hear a very weird sputter that comes from the left side. Itís almost like a sucking sound coming from the left pod. After the bike has been running for a while the idle hangs when I blip the throttle and Iím assuming itís not getting enough fuel. What are my options here? What do I need to do to fix this?

  2. #2
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    Default

    got original CV carbs? If so, are the diaphragms in good condition?
    Did it do this before you "put on brand new petcock, new in-line fuel filters and cleaned the carbs"? what type of petcock - with vacuum connection?
    float height set right? gas tank clean - debris not causing fuel flow issue?
    possible air leak at manifold?
    Electrical system all good with fully charged battery?

    maybe something here:
    TECH INFO & HOW-TO GUIDES
    CB / CL 350
    https://www.common-motor.com/CB350-C...L350_bc_1.html

  3. #3

    Join Date
    Nov 2018
    Posts
    4

    Default

    Itīs a common problem. Mostly a mix of petcock and carb problems. My solution is XL125 petcock (single port with y-tube) and VM30s. This works.

  4. #4

    Join Date
    May 2015
    Posts
    712

    Default

    Quote Originally Posted by JanKK View Post
    Itīs a common problem. Mostly a mix of petcock and carb problems. My solution is XL125 petcock (single port with y-tube) and VM30s. This works.
    My money is on the in line filter, new or not (I have found they are VERY restrictive, new or not) , and a crappy/filthy petcock that needs to be replaced

  5. #5
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    Default

    I haven't had much garage time this week but I was able to pull off the carb and clean everything again. I double checked the float heights too. I put everything back on and semi synced up the carbs and the bike seems to idle way better, although the idle does seem to hang just a little. I still get a little sucking from the Pod but I haven't tried messing with the mixture screws. Later this week my friend is giving me side covers and the stock air boxes from an old CB. Once I pop those on I'll try to do and mess with the mixture screw.
    One other thing, I tried to sync the carbs turning out the throttle cable barrel adjusted until the idle set screw starts to move but I can only do that on one side. The other side doesn't want to work that way so I've been adjusting both sides until the both actuate at the same time.

  6. #6
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    Today I had a chance to play around with the idle mixture screws and the right side seems to be running smoothly but I can't get the right side to run on one cylinder. It will run with the throttle wide open but it's kinda rough. I also tried to run it on choke to see if it ran better or worse. It ran the same with the choke on and off. Im thinking a can rule out carb issues and maybe look as spark/ignition coin. Whats my next step? Im thinking I should try to run the right side wire on the left to see if it runs better.

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