1. Dismiss Notice
  2. Dismiss Notice
  3. Hey Facebook people... We've created a group for XS650.com members to connect. Check it out!
    Dismiss Notice

1981 XS 650 Charging system issues

Discussion in 'The Garage' started by XSnin0, Mar 3, 2015.

  1. XSnin0

    XSnin0 XS650 Member

    Sorry Mods if i posted this in the wrong section, still getting used to the forum, i meant for this to appear under Electrical as it pertains to the subject

    First of all i want to say i hate for this to be my first thread instead of a proper intro thread. I'm a long time lurker of this forum and i must say there is a lot of good information for this particular platform thanks to contributions from members in this community, what makes it much more valuable is that even though this platform is almost 50 years old and yet there is still plenty of support out there both from aftermarket manufacturers and from awesome forums like this one so all sorts of xs owners worldwide can keep these amazing bikes on the road. Thank you all for your helpful contributions!

    So after looking for a nice xs starter for quite some time, i finally came across what i found to be a fairly good slate to build onto.

    1981 XS650 with a big bore 750 kit, Mikuni 34MM's, and Boyer Brandsen adjustable ignition

    More info/details and progress of the bike will be documented and logged on a progress thread at a later time as i continue with the build, for now first things first - getting this thing on the road....realiably. As in 500mile roundtrip to
    Daytona Bikeweek by next week's end reliable..

    Issue at hand - Charging system
    So the charging system on this thing just doesnt work, how do i know? Well it's drained the battery(newish battery), twice, which lead me to put a multimeter to the battery's terminals to check both for voltage after the battery has just been recharged. and after the engine is started and reved up to various speeds on the RPMs. Instead of voltage numbers going up when engine is started as they are supposed to, the voltage readings start decreasing, not drastically since the battery is newish, but they surely start lowering.
    Let me just buy a new regulator/rectifier and i'll be done with this, well thats what i initially thought as this has been an issue on other bikes i've owned in the past, i had this same issue with an R6 and its a fairly common issue on alot of motorcycles, and replacing the rectifier and/or stator will solve it in most cases. But when it comes to an old bike like the XS, this changes as it uses an older style charging system - with more components that can go bad - and replacing these with a used part isn't a very good idea since a 'used part' is often a 30+year old part that may either be bad or on its way out, and ofcourse purchasing brand new charging system components can be costly, and in the case of the XS maybe not so efficient since there are options to upgrade the entire charging system -to a newer and more efficient type- for the cost of entirely new components or even less in some cases. Also after looking thru the forums, i found that there are many parts that can go bad in this bike such as the insulation on the rotor itself which will cause it to short out and fail, magnet weakening out over time, wire brushes that wear out and not make contact as opposed to always coming down to a bad reg/rec.

    I then proceeded to test the rotor, pulled the side case and surprise, a few stripped screws, dirt, grease and other grime in a spot that should be rather clean. cleaned as best as i could and removed the brushes, then proceeded to test the rotor since i couldnt pull it out for 2 reasons, 1 the bolts that hold the stator casing in place are stripped to shit, getting them out would imply them being out for good and i need them for obvious reasons until i can get some replacement screws, and 2 even if i had removed the stator and nut that hold the rotor in place i dont have the removal tool or a flywheel tool to remove it without damaging it, so i took readings with the rotor still on, and this is what i got *scratching my head :umm:
    "Set your multimeter to reading Ohms in the appropriate range, then test for resistance from the 2 separate rings, anything below 4.0 and your rotor is toast"
    After reading numerous threads here, on chopcult, and even here:
    This is what i came up with, i was expecting to get a reading, something, 4.8, a 2.2, anything, but instead this is what i got, i was not expecting to get a 0 reading, i made contact with different spots on the rings and still nothing, wiped them clean with electronics cleaner and still nothing, my question is how rare is it to get a 0 reading from the rotor? i would think it would have some sort of resistance even if its not above 4 Ohms. Or is there anything im doing wrong?
    I then proceeded to run the continuity tests, one lead on one of the rings and the other at the base in the center by the nut, and the tester didnt beep.

    At this point im a bit confused, and i dont know what to do next, i dont want to order a new reg/rec from mikesXS because i know that if i have a bad rotor it will basically make the reg/rec go bad again, i dont know if i should pull the trigger on a new rotor because not only is it pretty expensive but im not 100% sure its bad and it will fix my problem and not give me any other charging system-related problems down the line.

    Basically i dont know if i should even try to replace the bad components on my stock charging system, or if i should just upgrade to a Permanent Magnet Alternator system and which route is the smarter way to go

    I've narrowed it down to these 3 options
    I can either:

    1. Replace the rotor for a new or 4.5+Ohm rotor, and hope reg/rec is good, if reg/rec is bad then either go the Chrysler rec route, or get one from MikesXS, and hope the stator is good, if not dish out another 140 for a new stator.
    Anywhere from $100-$350 depending on how lucky i get and what route i choose to go.

    2. Upgrade to a PMA system with a conversion swap, try and piece one together with banshee and other components as others have done, not exactly sure on how to go this route and what is needed and the availability of parts, also i dont know how long this may take.
    Anywhere from $100-$250?

    3. Buy a 'plug and play' kit such as PAMCO, Hugh's Handbuilt, or a few other available through MikesXS, my only question with going this route is, are these truly the only way to get rid of the charging system weak link on the XS? How reliable and quality built are these kits and what are your experiences with them?
    Anywhere from $250-$600 bucks. depending on the one i choose.

    Things to note: 1981 XS650 Special(CDI), with a 750 Big Bore kit and Boyer Brandsen Ignition system
    Essentially im looking for the most reliable option, that gets rid of the charging system problem for good so i wont have to worry about it later down the line as the project continues, and that doesnt break the bank!
    This bike will either end up as a cafe or Hardtail bobber, looking to stick with power ignition and a battery as this is a high compression 750cc motor that is a BITCH to kickstart everytime.

    Your input, opinions, experiences, and suggestions are greatly appreciated and welcomed.
    Time is of the essence as i plan on riding the bike for Bikeweek to Daytona friday the 13th.

    Thanks in advance
  2. Pamco is an ignition system.

    I'd replace the rotor with a good one or get a good shop to rewind it. Pma quality as of late has been shoddy with Chinese quality and all. But that's me. 2 perfectly good stock charging systems.

    the stock system is a good system. Weak batteries wreak havoc on it. It lasted over 30 years. Don't buy mikes rotors. More China junk. ..

    Posted via Mobile
  3. XSnin0

    XSnin0 XS650 Member

  4. kevski

    kevski XS650 Addict

    kent uk
    It may pay you to test the output of the alternator before going to huge expense, do this by disconnecting the block under the seat between the carbs before it goes to the main harness, and test the voltage output of the three white wires from the alternator while running you should get between 10 and 11 volts much lower than ten and its either your rotor or stator, if you get ten and above it's a problem within the harness normally. To test use the meter on 3 combinations of two whites to give you the voltage also crank the idle up to about 1250 rpm.
  5. pamcopete

    pamcopete Ride.Enjoy.Life is Simple


    Test your multi meter to see what the reading is with a short by touching the test leads together. I think that the reading you show here is infinite, meaning that there is not any excessive current from the regulator so it is probably good and all you need is a rebuilt rotor. The best rewound rotor source is:

    Custom Rewind
    2014 Pratt Hwy.
    Birmingham, AL

    800 798 7282

    If it is an open and not a short, then in many cases that is because one of the wires from the winding has come loose right at the terminal for the slip rings and it can be soldered back on, so check for that possibility.


Share This Page