Rotax Starter Question

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  • #42776
    Scott Mowrey
    Participant

    Okay, since you guys were so good with the jetting/gearing questions, here’s another one for you…

    Tonight, I removed and checked out the carb, air filter, and such. It all looked good and clean. Put everything together, put a lower gear on the axle (I had an 81 laying around), tightened everything down, hooked up the battery, hit the starter switch……..and nothing. Won’t even crank.

    The starter was intermittent on Saturday but I did not pay too much attention to it since I was so focused on the jetting/gearing issue. Anyhow, I started checking the electrical system. Battery has 12.5 volts (it’s new and charged). When I engage the starter the voltage drops, as expected, but goes all the way to about .1 volt, which indicated a short. I disconnected the starter connector and ohm’d out the starter, and I show .2 ohms to ground through the starter. I would assume this is not good…most functional starters are at least a few ohms. My question is- would this be the brushes or do I need to shell out some bucks for a new starter? If it’s the brushes, is there a procedure for changing them- I could not find anything in the manual.

    However, if the starter is crapped out, anyone got one for sale? *sigh* I really want to get out to the track Friday afternoon…..

    #61645
    Garrick Mitchell
    Participant

    I haven’t had to service my starter (yet), but I understand the starter is the same as that for the Leopard engine, even if it’s mounted a bit differently. The Leopard manual has a procedure, including helpful hints on retaining the brushes during rotor replacement and securing the brush wires with silicone:

    http://www.artkart.lt/championkart/manual.pdf page 35

    On my starter, which AFAIK is still functional, I get 0.5 Ohms between the power plug and a randomly-chosen bolt head on the engine (hey, I’m a Mechanical Engineer, not Electrical, OK?). Dunno if that’s a significant difference, considering how beat-up my multimeter is. Is there any sign the starter is even trying to turn? Is the reducing gear seized up with gunk? The one time my starter wouldn’t crank, the fix was a new battery and dielectric grease on the terminals. I know you say your battery is new, but stranger things have happened… Consider getting a spare battery (you should have one anyway) and try it or someone else’s “known good” battery before doing any serious teardown.

    #61646
    Scott Mowrey
    Participant

    Garrick,

    Thanks for the info, the manual really helps! My background is electrical (I designed, installed and troubleshot aircraft electronic (avionics) systems for around 20 years before getting into sales). The battery is new and works well. The starter won’t even turn when I jump it with the car. I suspect that the brush leads may have frayed or broken and are shorting out to the case. I think I will bite the bullet and pick up a brush set and try that tonight…

    #61647
    Scott Mowrey
    Participant

    Wow. Bad battery. Starter worked great hooked up to the minivan with jumper cables. Just pushing the kill switch in drops the battery to 2 volts. Will see if it slow charges tonight….

    #61648
    Doug Haner
    Participant

    From what I’ve heard jumping the battery with a car can be very damaging. You might want to pick up a battery tender.

    #61649
    Scott Mowrey
    Participant

    I didn’t jump the kart; I attached the starter to the minivan battery with jumper cables. I do have a slow charger for the battery and it indicated still on charge this morning, so I am going to get our battery shop here at work to test it….

    #61650
    Doug Haner
    Participant

    @Scomo wrote:

    I didn’t jump the kart; I attached the starter to the minivan battery with jumper cables. I do have a slow charger for the battery and it indicated still on charge this morning, so I am going to get our battery shop here at work to test it….

    Ohh, I see. Sorry for jumping to conclusions. I was just trying to help. Hope it all works out well for you.

    #61651
    Scott Mowrey
    Participant

    D fresh,

    No problem. Got a new battery from Billet today and will see if that fixes the problem…apparently the “cheap” batteries available for karts these days generally do not last the weekend.

    #61652
    Garrick Mitchell
    Participant

    It’s a crap shoot… I’ve been using an Interstate battery with good results (knock on wood). I’ve also heard of the spec Rotax Max battery giving up quickly.

    #61653
    Angel Ramirez
    Participant

    Some cheap batteries are as good or better than the $100+,rotax batteries. second year with my interstate battery. ($20.00) :loony:

    #61654
    Scott Mowrey
    Participant

    Put the new battery in and it works better than ever. I think the battery I got with the kart was bad out of the box…

    Interstate has always been a very reliable replacement brand. I had one in my Toyota pickup and it lasted 11 years. Would you have a part number for the kart battery? I’d like to have one as a spare.

    Woo hoo, now I can play hooky tomorrow and head to The Track!

    #61655
    Garrick Mitchell
    Participant

    I got an Interstate BSL1075, but I have an older wiring harness that presses on to two male spades at one end of the battery. I dunno about the newer-style harness with screw-on terminals located on opposite ends of the battery.

    #61656
    Scott Mowrey
    Participant

    Garrick,

    I have the older harness too. Thanks for the info- I’ll pick up one as a spare!

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