1. The Facebook Login has been removed Find out why and what to do if you log in using Facebook.
    Dismiss Notice
  2. Enjoy XS650.com? Consider making a donation to help support the site.
    Dismiss Notice
  3. Hey Facebook people... We've created a group for XS650.com members to connect. Check it out!
    Dismiss Notice
Facebook Login Donate Facebook Group

Charging system causing an engine miss ?

Discussion in 'The Garage' started by rstar45, Nov 23, 2011.

Tags:
  1. Nov 23, 2011 #1
    rstar45

    rstar45 XS650 Member

    8
    0
    1
    Colorado
    Newbies first post. TIA

    80 xs650 special
    The Story... My bike wasn't charging the battery so I did Curly's trouble shooting guide from another forum. The rotor had 0 ohms so I replaced it with aftermarket Chinese part, brushes still good. Seemed to be charging okay then, so I went for a ride. 50 miles later she started to miss badly just off idle up to about 3500 rpm. Limping home I notice the turn signals seem to make it miss worse so I'm thinking a voltage issue. Battery checks out fine, good voltage so I test the regulator / rectifier. All the diodes check good, not sure how to test the regulator part so I install the Chrysler regulator with the original rectifier using the brown and green wires with separate ground. Seems to be charging fine with max voltage of 15V revved. But still missing at lower rpms.

    At this point I need some trouble shooting help. I'm thinking did the TCI go bad also? But here is the kicker... If I disconnect the charging system at the 8 prong (7 used) plug from the regulator / rectifier at the harness, thus running her on the battery, the engine miss disappears and she runs fine. Could it be the TCI can't handle anything over battery voltage? The miss (severe) starts immediately off idle like maybe 1200 rpm or less and continues until she is revved up like maybe 3500 rpm or more.

    WTF HELP! :banghead:

    Rick
     
    rstar45, Nov 23, 2011
    rstar45, Nov 23, 2011
    #1
  2. Nov 23, 2011 #2
    650Dave

    650Dave XS650 Member

    18
    0
    1
    Since this started shortly after your rotor replacement, I would suspect that the magnet on the rotor that triggers the ignition is not strong enough. This happened to me, had exactly the same running characteristics. I glued a small rare earth magnet on top of the magnetized compound on the rotor, and that fixed everything. Dave
     
    650Dave, Nov 23, 2011
    650Dave, Nov 23, 2011
    #2
  3. Nov 23, 2011 #3
    weekendrider

    weekendrider Iron Horse cowboy Top Contributor

    5,668
    1,117
    213
    S.W. MO
    weekendrider, Nov 23, 2011
    weekendrider, Nov 23, 2011
    #3
  4. Nov 23, 2011 #4
    rstar45

    rstar45 XS650 Member

    8
    0
    1
    Colorado
    Hmmm... A weak pickup magnet on the rotor. Interesting, but since it runs fine on the battery alone wouldn't that eliminate the magnet?
     
    rstar45, Nov 23, 2011
    rstar45, Nov 23, 2011
    #4
  5. Nov 23, 2011 #5
    pamcopete

    pamcopete Ride.Enjoy.Life is Simple

    3,784
    290
    83
    South Carolina
    rstar,

    The magnetic field in the rotor, which is only there if there is current going to the rotor from the regulator, interferes with the weak magnet on the rotor and the pickups. A stronger magnet will not be affected. This is a very common problem as the TCI gets older, the rotor magnets gets weaker etc, etc.
     
    pamcopete, Nov 23, 2011
    pamcopete, Nov 23, 2011
    #5
  6. Nov 23, 2011 #6
    rstar45

    rstar45 XS650 Member

    8
    0
    1
    Colorado
    Ah Ha... explained that way I can see the connection. What glue do you recommend? Any clearance issues to watch for?

    The original regulator was probably okay... oh well at least I didn't pop big bucks for a combo unit.

    Much Thanks
     
    rstar45, Nov 23, 2011
    rstar45, Nov 23, 2011
    #6
  7. Nov 23, 2011 #7
    XSLeo

    XSLeo XS650 Guru

    12,420
    389
    133
    Lebanon NY
    I like JB Weld, The regular stuff not the quick set, the quick set won't take heat well. But any epoxy type glue that can handle high heat should work.
    Leo
     
    XSLeo, Nov 23, 2011
    XSLeo, Nov 23, 2011
    #7
  8. Nov 23, 2011 #8
    650Dave

    650Dave XS650 Member

    18
    0
    1
    No clearance problems with the Radio Shack magnet. Cheap, small, strong.
     
    650Dave, Nov 23, 2011
    650Dave, Nov 23, 2011
    #8
  9. Nov 23, 2011 #9
    rstar45

    rstar45 XS650 Member

    8
    0
    1
    Colorado
    Well guys I got the magnet glued on there. Sure hope JB weld doesn't have an expiration date as I have had it around for a good number of years. Got a trouble light keeping it warm overnight and will see how it runs tomorrow. I'm betting on it cause it sure makes sense. Quality Chinese parts and all :mad: .

    Anywho... Happy Thanksgiving everybody and Thanks again.

    Rick
     
    rstar45, Nov 23, 2011
    rstar45, Nov 23, 2011
    #9
  10. Nov 24, 2011 #10
    pamcopete

    pamcopete Ride.Enjoy.Life is Simple

    3,784
    290
    83
    South Carolina
    rstar,

    A little late, but if you still have the original rotor, compare the polarity of that magnet to the one you just glued on. You can use a boy scout compass or another, weaker magnet. Do not use a strong magnet for this check as that may reverse the weaker magnet on the rotor. I know that you installed the new magnet with a matching polarity to the magnet on your new rotor, but I'm suggesting that that new rotor could have the magnet installed back wards. It has happened.
     
    pamcopete, Nov 24, 2011
    pamcopete, Nov 24, 2011
    #10
  11. Nov 24, 2011 #11
    rstar45

    rstar45 XS650 Member

    8
    0
    1
    Colorado
    Well guys, I got lucky on the magnet polarity. AND the miss is gone. Ya all nailed that one!!! :cheers:

    BUT... now I am concerned about the timing. The Chinese rotor and the design of the indicator on the stator and the 80 model pickup being immovable doesn't exactly inspire confidence.

    Here's the deal. I rigged up a pointer wire on a cover bolt to check the timing mark of the Chinese rotor against the OEM rotor using the crankshaft key as a guide. The Chinese mark was about 3 degrees advanced from it's location on the OEM rotor. Unfortunately I didn't think to compare the location of the magnets. I reinstalled the stator using the witness marks left by the locating lug on the case. The strobe light tells me it is firing on the Chinese mark so I'm thinking I am 3 degrees over advanced.

    My dial indicator doesn't have a long enough shaft to get in the plug hole to find TDC. Are there any other accessible TDC marks on this engine? Am I going to have to swap back to the OEM rotor to check the magnet locations? Suggestions?

    Rick
     
    rstar45, Nov 24, 2011
    rstar45, Nov 24, 2011
    #11
  12. Nov 24, 2011 #12
    weekendrider

    weekendrider Iron Horse cowboy Top Contributor

    5,668
    1,117
    213
    S.W. MO
    Couldn't you just measure from the mark to the magnet on both?

    The pickup can be moved by drilling the rivets or screws and replacing.
    Search for xsjohns post on it. He had some pics in the thread I think.

    a wooden dowel on the piston will let you find tdc.
     
    weekendrider, Nov 24, 2011
    weekendrider, Nov 24, 2011
    #12
  13. Nov 24, 2011 #13
    rstar45

    rstar45 XS650 Member

    8
    0
    1
    Colorado
    Well I g