Mixing Sportster and big twin OSGR starters, parts interchange and more.

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  • farmall
    Senior Member
    • Apr 2013
    • 9983

    Mixing Sportster and big twin OSGR starters, parts interchange and more.

    The Denso OSGR Light Duty starter may be the most successful starter design in the modern era for cars, trucks and motorcycles. That means you have many parts options.

    Some Chop Culters live in countries where HD parts are few and expensive but labor is cheap. These starters are common worldwide except for those with Harley end housings, but if you have the HD parts you can get the rest elsewhere. This post will aid your salvage yard pillaging.

    The main casting (contains the solenoid windings and for which HD doesn't show a part number) on OSGRs used on big twin and Sporties is the same part. The one on a Sporty I just bought is cracked and I didn't feel like buying a starter, so I grabbed a used big twin starter and looked up the differences to make one out of two.

    Sportster starter exploded view:


    BT starter same year (1992):


    OSGR parts. http://www.metroautoinc.com/PDF%20Fi...ght%20Duty.pdf

    BT units use a jack shaft and a different "housing, starter" referred to in starter lingo as a "drive housing". Compare parts and part numbers when going from one to the other and you'll see what doesn't match i.e. drive housings and pinion gears etc.

    Pics show a stock 1992 Sporty drive housing on left (with pinion gear etc) and an anonymous aftermarket big twin drive housing on the right. There are many Denso starter videos on Youtube so refer to those for disassembly/reassembly.

    If you have appropriate car or truck starters you can cannibalize those. Non-shit auto stores will have the contact kits which should be replaced unless they are unburnt and very clean. Sanding/filing works in an emergency. Not all contacts are the same because of slightly different post positions on the housing. Make sure yours match.

    I use silicone tuneup grease on the electrical contact stud threads so the next removal will be easier.

    Use six point sockets when replacing the contacts to save the hardware (the 14mm and 12mm nuts are shallow and soft).
    I grind the chamfer off the 14mm socket to flatten the fastener end for more engagement. The insulating washers can interfere with the socket so make sure you have the socket aligned square to the nut. You could taper the outside of the socket end to get deeper but it's hot out and I don't feel like running the lathe today.

    Grainy pic shows "solenoid winding housing" (for lack of a better name). The windings are firmly installed (until they meet my hydraulic press for dissection) and the external connector (other side, not shown) is permanently mounted so for practical purposes ya gotta replace as a unit, and if you have another set of windings they are in the same housing so no need. These are not model specific.

    There are many OSGR starter variations. Different KW rating starters may have larger electric motors so if room permits I'd use the larger if you have one. The motors are retained with two long bolts. Keep those with their motor as lengths may vary. If you know your motor is dead you can remove those and disconnect the cable from the motor to the stud on the solenoid to replace it. No gaskets or seals needed. That could be a useful roadside fix without removing your outer primary cover to unbolt the starter.

    Problem:
    Dead solenoid windings. Contacts usable.

    Option: Replace noid housing complete. Use pushbutton end cap you should have installed already or drill hole in stock end cap then push with appropriate object like screwdriver or remove stock end cap and push in noid core, then reinstall cap or put the core (and the long coil spring that rides on its shaft) in your pocket and use as needed to start.

    Problem:
    Motor doesn't spin when you put 12V direct to it, bypassing solenoid.

    Option:
    Swap motor.

    In an emergency you can use sealant on the outer primary gasket/gasket area. If it drools, replace later.
    EDIT:
    Added pic of jewelers screwdrivers holding back brush springs for commutator insertion after cleaning commutator. The springs are stiff enough you need some appropriately stiff wire or small drill bits or whatever to lift the springs off the back of the brushes so you can push them out of the way to clear the commutator. Work clean if possible keeping grease off the brushes and commutator.

    Example Dorman kit with listing of (four wheeled) vehicles it fits. These contain extra contacts for both style solenoid housings. Your holes for the posts may not be in the same place on different housings and this covers that, too. You can drill another hole to relocate a contact if useful, as another Culter posted elsewhere. (Apologies for forgetting which thread. A 29/64" drill bit does the job but do a pilot hole and take your time so it doesn't snag.)



    Harley style OSGR starters. Got a starter but not sure what it fits or need to replace some oddball custom unit? This lists shaft threads for jackshaft bolts and starter clutch direction of rotation (CW or CCW) too.



    Solenoid end cover screws are M4-0.7X12 Stainless socket head screws are cheap by the bag via Ebay.

    EDIT:
    More info about control wiring and relays here:
    Put a BDL 2” open primary w/electric start on my 1970 chop . Never had this starter before , it’s an All Balls 1.4kw starter that fits the BDL Shorty Belt Drive . Have it hooked up the way I would think it should be . Hit the starter button and the jack shaft just comes out and doesn’t spin . Can’t find any instructions online


    EDIT Sept 2022:
    You can get longer terminal studs (normally part of the contact kits) which let you fit more ring terminals for dual batteries so you can run duplicate cables for max ampacity and to avoid overheating. Your local auto electric shop will have many Densos and the contact studs are 8mm x 1.25 thread. You can order different nuts like stainless acorns to tidy the result.

    I ordered the 38mm studs so I can cut to length or use as-is since my FXR is getting dual batteries.

    Check out the deal on M8 x 1.25 x 38mm Solenoid Bolt - 10 Pack at Sherco Auto & Marine Supply: Automotive Supply, Automotive Wire & Electrical Connectors
    Attached Files
    Last edited by farmall; 09-04-2022, 1:53 AM.
  • hazydaze
    Member
    • Jan 2016
    • 35

    #2
    Thanks! Super good info... i was cursing my electric start sportster because I've been getting the run around with this starter working when it wants to.. starts to spin slower or click a couple times and its suddenly a race to get home without shutting bike off.. i think its probably my charging system because ive had to do "maintenance" charges on a new battery more than ive ever done before in my life and its a daily rider...bought a cheapo ebay regulator for it that had the wrong connectors for my year so i just made the correct ones and the thing still doesnt charge shoulda spent the $$$ on something better, oh well this info helped me a alot so thank you!

    Comment

    • farmall
      Senior Member
      • Apr 2013
      • 9983

      #3
      Perform a charging system test with a meter per your factory service manual or the info on the Cycle Electric website. Inspect all connections including alternator to regulator and grounds.

      The add-on pushbutton solenoid end covers are cheap (about 20 bucks) and work well as backup if the little starter relay or control wiring or handlebar switch fails.

      Comment

      • cranberrybeecat
        • Apr 2024

        #4
        Outstanding Work. I'm still new here and still learning and taking all your wisdom

        Comment

        • ironallen
          Junior Member
          • Jun 2012
          • 25

          #5
          Thank you!

          Comment

          • Dragstews
            Senior Member
            • Sep 2010
            • 13739

            #6
            Originally posted by cranberrybeecat
            I'm still new here and still learning and taking all your wisdom


            .... RUN farmall Run ....
            Take my 45 and outrun em all ..

            Comment

            • farmall
              Senior Member
              • Apr 2013
              • 9983

              #7
              A tool I don't have? I'll have to run towards it and that may not end well.

              Comment

              • Dragstews
                Senior Member
                • Sep 2010
                • 13739

                #8
                Originally posted by farmall
                I'll have to run towards it and that may not end well.
                Speaking of running ...

                I'm about ready for the donor bumper ...
                My fat fenders are on their way down to me ..

                Once they show up, it's get busy time and ......

                Click image for larger version

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                Take my 45 and outrun em all ..

                Comment

                • JayKonquer
                  Junior Member
                  • Mar 2022
                  • 1

                  #9
                  thanks for the useful info.

                  Comment

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