Bike Won't Go Past 4000 RPM - Page 4
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  1. #31
    Member jgordonoglan's Avatar
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    Quote Originally Posted by jjdugen View Post
    My 350 does exactly this, if I forget to knock the choke off once warm. The choke only has to be on by a few degrees too.....
    I thought that might be the case too since my choke cable is stuck. But when I took the carbs off I just never bothered to reattach the choke. I’ll take another look to make sure it is seated properly and completely closed though.
    Jarrod

    1982 CB450SC - first bike

  2. #32
    Member jgordonoglan's Avatar
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    Quote Originally Posted by longdistancerider View Post
    I played with 3 CDI's and 3 stators and the advance was late on all combinations.
    In checking the timing you're going to be looking for it to advance with the throttle. If it doesn't advance then it likely is the stator, not the CDI. Use your VOM and run thru the ignition tests in the thread I linked earlier.
    Looking to attempt to get this bike running again and I just want to clarify, the stator is the rectifier/regulator or is there another part?
    Jarrod

    1982 CB450SC - first bike

  3. #33
    Sensei 66Sprint's Avatar
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    The stator is the large set of windings mounted on the lower left side of your engine primarily under the magnetic dome shaped rotor......
    It contains both the alternator windings (to recharge the battery), and the ignition pick-up coil (exterior to rotor) and advance coil (within rotor) that trigger and control ignition timing........
    Failures to rev past 4K are often due to the advance coil/winding failure...This is not a separate part and the stator is replaced as a complete unit......
    The stator can be tested by verifying the Ohm readings are within the specific ranges listed in the factory service manual.......
    Jim, (longdistancerider) has provided a good discussion topic detailing this procedure, and it can be found in the SOHC electrical section.....
    "I have a mind like a steel trap.....Old and rusty, of antiquated design, and hard to get stuff back out of...."
    Contact info: E-mail; [email protected] Phone; 540-525-5199

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  5. #34
    Member jgordonoglan's Avatar
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    Quote Originally Posted by 66Sprint View Post
    Jim, (longdistancerider) has provided a good discussion topic detailing this procedure, and it can be found in the SOHC electrical section.....
    He’s posted the link to it for me already, I just wanted to make sure I knew which part we were talking about and I was definitely not thinking the right part. Thank you for clarifying this for me!
    Jarrod

    1982 CB450SC - first bike

  6. #35
    Member jgordonoglan's Avatar
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    Quote Originally Posted by longdistancerider View Post
    Here's the relevant thread for the ignition https://www.hondatwins.net/forums/64...78-1986-a.html
    I've gone through all the measurements on this thread and everything seems pretty good. I did however get these with the run/kill switch:

    Ignition Switch Off = Infinity
    Ignition Switch On, Kill Switch Off = -123

    I'm not sure if I was just having issues getting the probes on there properly for those two or what, but it seems like since everything else was in then maybe the CDI might be my issue after all.
    Jarrod

    1982 CB450SC - first bike

  7. #36
    Senior Member drydreamer's Avatar
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    So the bike engine will not rev past 4 to 5 k revs and it seems like a fuel issue, or a ht coil breaking down..........you have used the red neon plug caps so you can "see" the spark ( the red neons flash as they pass ht to the plug ) or spark loss.

    The engine seems to surge at about 4 to 5 k revs and slows down a bit then re revs etc.etc.etc.

    Have you check for proper ignition advance?

    Have you checked acv outputs of the genny ign system wires?? as a rule all acv values should rise with increase in engine revs, rate of change.

    disconnecting the cdi black/white wire will disconnect the cdi from the rest of the bike. earthing this cdi black/white wire kills the ign. Sometimes the handlebar dedicated kill switch can cause problems, especially when wet.

    cdi's have been know to "die over night" which has happened to my sons 400, then a few months later the genny stator died.........

    a multimeter will show acv and a pulse to the ht coil, but a scope will show much much more.....

    you have a wiring diagram and know that the genny ign windings are on the same stator as the charging system coils but are completely seperate........the reg/rec is the black finned unit by the fuses........3 yellow, a black and a red/whiter from memory.......
    Last edited by drydreamer; 09-11-2019 at 04:08 AM.

  8. #37
    Super Moderator longdistancerider's Avatar
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    Quote Originally Posted by jgordonoglan View Post
    I've gone through all the measurements on this thread and everything seems pretty good. I did however get these with the run/kill switch:

    Ignition Switch Off = Infinity
    Ignition Switch On, Kill Switch Off = -123

    I'm not sure if I was just having issues getting the probes on there properly for those two or what, but it seems like since everything else was in then maybe the CDI might be my issue after all.
    Probably just a probe problem but you can open up that switch and clean the contacts since it's exposed to wet weather=corrosion
    Before replacing a CDI it's useful to use a timing light and check the advance. It sounds like you're not getting any which is controlled between the stator and CDI.
    Jim O'Brien
    1979 CM400T "road bike" modified for travelling
    1978 CB400T1 restored
    1972 CL350 nuts and bolts restore in progress


    https://www.hondatwins.net/forums/22...d-attempt.html and https://www.hondatwins.net/forums/1-...r-attempt.html
    Road Trip https://www.hondatwins.net/forums/11...here-i-go.html or "where's Jim now?"
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  9. #38
    Member jgordonoglan's Avatar
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    Quote Originally Posted by longdistancerider View Post
    Probably just a probe problem but you can open up that switch and clean the contacts since it's exposed to wet weather=corrosion
    Before replacing a CDI it's useful to use a timing light and check the advance. It sounds like you're not getting any which is controlled between the stator and CDI.

    I checked the timing and it's on 'F' on start up. When I twist the throttle it moves towards the 'II' mark.

    Do the marks need to be perfectly on the index mark? The 'F' appears to be a bit ahead of it on idle, and the 'II' seems like it struggles a bit to get to the index but it does get there. That's the point when it hits 4000RPM and won't go any further.
    Last edited by jgordonoglan; 09-14-2019 at 02:21 PM.
    Jarrod

    1982 CB450SC - first bike

  10. #39
    Sensei 66Sprint's Avatar
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    Quote Originally Posted by jgordonoglan View Post
    I checked the timing and it's on 'F' on start up. When I twist the throttle it moves towards the "II" mark.
    At what RPM does it move all the way to in-between the two marks? (in the middle of the II)?

    EDIT....You answered while I was typing the question....
    Last edited by 66Sprint; 09-14-2019 at 02:24 PM.
    "I have a mind like a steel trap.....Old and rusty, of antiquated design, and hard to get stuff back out of...."
    Contact info: E-mail; [email protected] Phone; 540-525-5199

  11. #40
    Sensei 66Sprint's Avatar
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    Now the question becomes what is your idle RPM?....

    AND YES, EXACTLY on the F mark alignment......
    Sounds like you are starting out partially advanced at idle, and thus it can't fully advance the necessary number of degrees beyond that initial setting......

    Have you checked for a damaged (crank to rotor) key or key-way?
    (Which would shift advance timing slightly. making it difficult to smoothly increase in RPM, with incomplete fully advanced position causing the peak RPM limit/stoppage )

    While the rotor is off to check that, look at the advance pickup coil to check for overheating as a short there would "read" erroneously to the CDI...(Although your prior Ohms readings SHOULD have told that tale......)
    Last edited by 66Sprint; 09-14-2019 at 02:46 PM.
    "I have a mind like a steel trap.....Old and rusty, of antiquated design, and hard to get stuff back out of...."
    Contact info: E-mail; [email protected] Phone; 540-525-5199

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