Cb450k6 Issues Please help
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Thread: Cb450k6 Issues Please help

  1. #1
    Junior Member Saltychips's Avatar
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    Cb450k6 Issues Please help

    Hello,

    I rebuilt the carbs twice to find out the points had a pinched wire so that's taken care of however, whenever I'm in gear, clutch in, the bike will start to rev high on its own and almost redlines when I give it the tiniest amount of gas. I was riding down the street and it just kept going with zero throttle and then stops accelerating after a second or two. It's extremely scary not being able to control the bike when your need to decelerate. I also recently changed the bars and am thinking it's the throttle cable or control but not exactly sure.

    Lastly, the bike rides really rough and slips out of 2nd gear. should i start with value adjustment and cam chain?

    Any recommendations on where I should start would be greatly appreciated!

    Thank you!

  2. #2
    Senior Member ancientdad's Avatar
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    First, you should post an introduction so we can get to know you (mechanical background/skills/aptitude, bike experience in general) and your bike. Since you changed the bars, cable routing could easily be a factor and pictures always help. Cam chain and valve adjustments are always helpful on an older bike, but that is not going to help your 2nd gear problem... and I can tell you with certainty that if you continue to ride it and let it jump out of second gear, you'll be doing further damage to things that might just be okay right now - shift forks - and that will require a bottom end teardown and repair. Right now, it's probably the shift detent mechanism and related worn parts at fault, it's a pretty typical issue with 450s as the parts age. Trying to answer questions like this without any visual aid is the reason introductions with pictures are helpful
    devilclown likes this.
    Tom

    Ride along at the drag strip - https://www.youtube.com/watch?v=20jFPazXlvU



    running points... because I'm too old for mysteries that begin with pushing

  3. #3
    Senior Member 76TWIN's Avatar
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    What exactly did you do on the carbs when you stated you rebuilt them. What did you replace exactly?
    Here's a quick check list based on what you told us so far.

    1. Take the tank off and see if the revving issue continues. If not then you have a throttle cable routing issue and something is caught up somewhere. What bar did you change to? Again more details and pics would help
    2. If the Revving continues then likely you have a vacuum leak somewhere either on the carbs or the boots. Check by spraying some carb cleaner around the boots and carb bodies to see if the idle suddenly picks up.
    3. If there is no vacuum leak as checked from above then check your ignition advance and see if something there is stuck.
    4. Regarding the gear slipping, what oil are you using? You cannot just use regular automotive oil in these bikes since they have wet clutches. You need to use oil rated for JASO MA
    Rotella T4 is a cheap good choice for this.
    If everything else checks out then it's probably the shift detent mechanism like Tom stated above.
    '76 CB500T Frankenbike
    '73 CL450 (basket case for now)


    Carpe narem.

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  5. #4
    Junior Member Saltychips's Avatar
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    Thank you so much guys! I'm going to try my best to get to all of your questions asap however I just noticed the throttle linkage is hanging up and gets stuck when playing with the throttle. I can push it back down easily but every time it hangs up mid way and won't go back down.

    Still trying to figure out how to post pictures through replys

  6. #5
    Senior Member ancientdad's Avatar
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    Here's how to post pictures from a computer

    Cb450k6 Issues Please help-post-pics.jpg
    Tom

    Ride along at the drag strip - https://www.youtube.com/watch?v=20jFPazXlvU



    running points... because I'm too old for mysteries that begin with pushing

  7. #6
    Junior Member Saltychips's Avatar
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    Thanks, Ancientdad! Just posted an intro.

  8. #7
    Junior Member Saltychips's Avatar
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    Hi 76 Twin. So the guy who was working on it rebuilt the carbs so I honestly do not know if he replaced anything. I had no issue with this previously, so I definitely know it happened in his hands.

    Took the tank off and the cables seem to be perfectly fine and synced. At first I thought it was fixed when I removed the tank but then link got stuck again. I can feel tension once its raised above the halfway mark (image attached). I believe this is why I had no control and kept accelerating

    I just got some regular bars from Common Motors - https://www.common-motor.com/honda-superbike-bars

    Thanks for the oil recommendation! I really appreciate it! I use Rotella for my old diesel and is some good stuff!
    Cb450k6 Issues Please help-img_20190721_183239.jpg
    Cb450k6 Issues Please help-img_20190721_183406.jpg

  9. #8
    Senior Member 76TWIN's Avatar
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    Call him up and ask for for original carb parts if he still has them. The reason why I say that most aftermarket carb rebuild kits do not have the properly sized jets and needles and will cause all kinds of problems.
    Unless they are damaged, I have never found a reason to replace any brass parts (jets, needles, etc...) on the carbs. The only things needed to be replace were gaskets and o-rings.

    Take your throttle cable off and check to see if it is moving freely. It maybe partially broken or kinked inside and causing the hang up. Replace as needed.
    '76 CB500T Frankenbike
    '73 CL450 (basket case for now)


    Carpe narem.

  10. #9
    Supporting Member jd50i's Avatar
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    Also see if the throttle cable has curled at the ends where it connects to the carbs, this can also hold the carbs open.
    Jim

    1973 CB 450 K6 PAMCO
    1975 CB 500T PAMCO
    1985 CB650SC Nighthawk
    1985 VF 1100S Sabre
    2012 Buddy 125 (wifes)

  11. #10
    Junior Member Saltychips's Avatar
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    Removed the cable and it still sticks. Do you have any recommendations on a good carb rebuild kit? Im worried its the spring.

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