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Starter Gear Fix!

Discussion in 'The Garage' started by garyr, Apr 24, 2012.

  1. garyr

    garyr XS650 Enthusiast

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    Below I documented the fix for the slipping 4th starter gear. I want to add the original poster/author is below. All I did was test and post pictures to what he is writing about. I applied this fix years ago to a kick starter spring the same way with success.

    The reason why the starter slips and spins out because the spring has lost it's tension or was never set properly. This is what I found.

    The spring has to be at 6 pounds. I found when it gets to 4 pounds it slips. I tested this on 3 other bikes. They were all at 4 pounds that slipped, new aftermarket-used aftermarket OEM or otherwise. Just takes 2 pounds difference.
    [​IMG]

    This is what happens to the gear when the spring is at 4 pounds pressure.
    [​IMG]

    This is a fish scale I bought at Walmart for $15.00. I'll keep it and use it to adjust the steering head.
    [​IMG]

    Here is the factory spring tension rate
    [​IMG]

    I have gotten two of Mikes stater kits for 2 of my bikes and one worked fine and the other just spun. This is what I've found on the adjustment. You can only squeeze the spring in a vise. No matter how hard you squeeze you only achieve 6 pounds. So if you don't have a scale you will be in spec. Just don't over squeeze on the vise and disform the spring.
    [​IMG]

    Here is what I've also found. On the left is Mikes spring. Notice the flat sides to fit the new gear. To the right is a OEM NOS spring, it's fatter-just not grinded flat. When I put a NOS spring on Mikes gear you only get 4 pounds. If you squeeze the spring you get 8 pounds so that is the best set up. *Note* if you put a OEM spring on a OEM gear you will only get 4 pounds, the spring has to be bent in a vise.
    [​IMG]

    You really can't bend it on the bike and not take it apart this this.
    [​IMG]

    OEM part #
    [​IMG]

    Below is a post from the author with his fix I just documented and tested. This will fix the dreaded starter problem. You could probably just remove the slipping gear and squeeze the spring and you would be fine.


    #Electric starter problems on the XS650 are very common, and almost always due

    to a non-functioning #4 gear, the one that slides down the bendix helix and

    engages the ring gear on the flywheel. Symptoms are a starter that does not

    engage, a starter that just grinds ineffectually, or a starter that kicks out if the

    engine does not start immediately. The usual remedy is to replace the gear

    complete with it’s spring clip, but there is an easy way to fix erratic and non

    functioning starters without changing the #4 gear, even if the gear is showing

    signs of severe wear.


    When people remove the offending gear it is often badly worn, and they

    assume that is the reason the starter does not work. But exactly the converse is

    true.

    IT IS NOT A CASE OF THE STARTER NOT ENGAGING BECAUSE OF A

    WORN #4 GEAR. THE #4 GEAR ONLY WEARS BECAUSE THE STARTER IS

    NOT ENGAGING.

    One will find in removing non-functioning #4 gears from an XS650 that there is

    still lots of tooth left. Now the bendix on a car will continue to engage till the

    teeth are completely snapped off, and even then will turn the engine jerkily.

    One usually changes them to avoid damage to the ring gear on the flywheel,

    rather than because they won't engage. It’s not the worn teeth on the #4 gear

    that prevents engagement. The reason the starter does not engage is because

    of the spring clip on the #4 gear losing it's tension. The manual calls for about

    5 lbs tension required to rotate the clip in it’s groove on the gear. The tension

    found on the new ones can be up at about 8 lbs. You will invariably find that

    the tension required to move the clip on non-functioning starter gears will be

    down to about 2 lbs or less. This can be measured using a fishing scale.

    What happens is this.

    Because the # 4 gear is light and does not have enough

    inertia (resistance to being rotated from a state of rest), Yamaha designed in the

    spring clip to increase the inertia. This restrains the gear from turning on the

    bendix when the bendix shaft is initially rotated by the starter motor. So, as the

    bendix rotates, the helix on the bendix shaft forces the gear down the shaft and

    into engagement, because the gear will slide before it will turn. Once it gets to

    the end of the bendix, by which time it is fully engaged with the flywheel ring

    gear, it has no option but to turn, it has nowhere further to slide. When the

    spring tension in the clip is too weak, there is not enough restraint, so instead

    of the gear resisting turning, it just spins with the bendix shaft, does not move

    down the shaft fully, and is not forced into engagement. It goes down just far

    enough to grind off it's teeth against the flywheel ring gear.

    All that is necessary to get a starter gear working, no matter how worn the teeth,

    is to bend the clip so it gets back to a minimum of 5 lbs required to move the

    clip.

    All that is needed to do is drain the oil, remove the kickstart lever, brake lever,

    foot rest, and disconnect the tach drive cable at the side cover. Then remove the

    right hand side cover. The best way is then to remove the clutch basket and

    dismount the #4gear from the bike. I haven’t yet tried to do this fix with the

    clutch still mounted on the bike and the #4 gear in place, but this may well be

    possible. I am pretty sure that on the newer units where the loop of the spring

    clip bears against the floor of engine case the that the loop will be visible just

    under the forward lower edge of the clutch assembly, and you will be able to

    reach in and do the following without further disassembly. On the older units

    with the clip with the skinny loop inside the recess in the crankcase, the clutch

    will definitely have to be removed and the gear dismounted. In any case, either

    way, just use a heavy pliers, like a linesman's pliers, or a Visegrip, to squeeze t

    he loop of the clip closed so it bends a little and the clip then grips the gear

    tighter. If you do remove the gear from the bike, lever the clip off the gear

    using a screwdriver, squeeze the loop of the clip in a vise, and remount it on

    the gear. Check the tension with a fishing scale, if it is less that 5 lbs squeeze

    the loop a little more.

    You can test it immediately, even before remounting the clutch. Pull the spark

    leads so the oil-empty engine does not start, and hit the starter button. I bet your

    starter will now work, no matter what the wear is on the #4 gear's teeth.

    Farrell

     
    Last edited: Apr 24, 2012
    rehar likes this.
  2. 5twins

    5twins XS650 Guru Top Contributor

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    Very nice. I knew about the tension but never saw it documented with actual measurements and numbers like you've done. A note on installing the drag clip. Lay it over the top of the gear and snap it down into the groove. Don't try to insert it from the side. That will spread it open too much and you'll lose the tension.
     
  3. weekendrider

    weekendrider Iron Horse cowboy Top Contributor

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    This should be a tech section sticky.
    Nice additons to Farrell's article garyr!
     
  4. colebrooker

    colebrooker XS650E US import

    Good post Gary, explaines a lot.
     
  5. sseres

    sseres XS650 Junkie

    are you saying that it's IMPOSSIBLE to over tighten the clip spring? I'm nervous I may have done that, but I'm having the starter-won't-engage symptoms (which seems like there's not enough tension on the clip). What symptom would I have if it were truly overtightened?
     
  6. garyr

    garyr XS650 Enthusiast

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    I found any amount of pressure with the vise leaves the correct spring tension. The idea is "snug" the vise NOT super,super tight. My guess is you can move the spring with you fingers when you take it out of your bike. Put the spring in the vise and snug it in the vise then take it out and if you can't turn it with your fingers it worked. When you sung the vise you will see the spring end loop move it's shape.. slightly. Note: like in the picture you bend the spring in the vise with the spring installed on the gear.

    And "NO" it's not impossible to over tighten it if you tighten the vise as hard as you can you could deform the spring. For the hell of it I tested an old clip and did tighten the hell of of it and my test it actually held fine and the shape stayed but I can't guarantee that for everyone with every type of vise. My point was I tried different pressures in the vise on the spring and they all gave me almost 8psi of spring pressure so you don't have to worry about how much vise pressure you use to achieve 8 pounds.
     
    Jwb02e likes this.
  7. sseres

    sseres XS650 Junkie

    Thanks! what's the reason they changed the position of where the bend in the spring sits in the case? Does it actually make a difference?
     
  8. garyr

    garyr XS650 Enthusiast

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    I don't know why. I know Yamaha changed that in the early to mis 70's. I would only put the spring in...in that grove. If you buy a Mikes gear and spring as stated above you need to also snug that spring in the vise.
     
  9. 5twins

    5twins XS650 Guru Top Contributor

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    Around 1975, the drag clip was updated and the new one was made from heavier wire. It wouldn't fit in the original groove any more so it was positioned just to the right of it.

    [​IMG]
     
    Last edited: Aug 22, 2017
  10. garyr

    garyr XS650 Enthusiast

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    Yes..Yes!!! thats what I meant..Thanks 5Twins :doh:
     
  11. If the spring is TOO tight, will it get stuck engaged?
     
  12. garyr

    garyr XS650 Enthusiast

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    No you can't make it too tight no matter how hard you squeeze in the vise, the spring will disform first and loosen actually. The more tension the better it engages.

    Just don't over think it. Just squeeze it in the vise and snug up the spring weather new spring kit from Mikes or OEM or the used spring itself.
     
  13. ontherocks

    ontherocks XS650 Addict

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    This should be stickied in tech.
     
  14. BruceDeuce

    BruceDeuce XS650 Addict

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    I see garyr isnt online and Im tearing mine down. If I may ask you a question 5Twins - I see that gary has the spring still on the gear in the vice. As Im going to re tighten my original spring, do I need to take it off the gear or do the same as the pic with the spring on the gear and tighten in the vice? Thanks
     
  15. garyr

    garyr XS650 Enthusiast

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    Good thing I get an email when someone posts...

    Only do it with the spring on the gear already and in place.. than tighten in a vice.
     
  16. BruceDeuce

    BruceDeuce XS650 Addict

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    lol that was fast thanks By the way Im in Central NJ
     
  17. 5twins

    5twins XS650 Guru Top Contributor

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    I've done it both ways, the last time just last week was with the clip on the gear, as Gary instructs. The time before that, I took it off. It works either way but leaving it on is easier. I now have a fishing scale too so I'm able to test the "fix".
     
  18. XSLeo

    XSLeo XS650 Guru Top Contributor

    It can't stay engaged because when the engine starts the starter stops spinning. This lets the return spring push the gear out of engagement. The engine spinning the gear faster screws the gear back on the splines as well.
    Leo
     
  19. oldbiker

    oldbiker oldbiker

    hi guys i have done the starter gear fix,,,,,i actually removed the spring from the gear and clamped it in the vice... then slipped it back over the gear...my teeth were slightly chopped ,so while i had it apart ... i put the gear in the vice and stonned the teeth ... then i re-assembled it it works like a treat... .y bike is a 1976 frame with a 1983 motor in it regards oldbiker
     

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