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Thread: 98 Softail Jackshaft Lock Plate keeps snapping/Fluctuating Idle

  1. #1
    Junior Member Just broke my cherry!
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    98 Softail Jackshaft Lock Plate keeps snapping/Fluctuating Idle

    Hello, my stepfather recently gave me his 98 Softail custom that was previously non-operational due to a starter issue. I have since replaced the starter and done some other general work like clean the carb, fuel tanks, replaced fluid etc.

    After installing the new starter (Screamin Eagle 1.8kw High Toque), I have since broken 3 lockplates and I have no idea why they keep breaking in the key way. I torque the jackshaft bolt to roughly 8-9 ft lbs as the manual states, bend the lock tab into place and they still just keep breaking. I should note that the lock plates don't break right away but after a dozen or so starts, they give out and subsequently the jackshaft bolt unscrews itself since nothing is retaining it. Any help on this subject would be great. I have been using 1993 type lockplates thus far. I'm thinking of buying a 1990-92 type and an 89 to see if maybe I've been using the wrong lock plates for my jackshaft. I'm also considering putting a bit of blue locktite of the bolt itself.

    Furthermore, just today my idle speed began to fluctuate quite wildly. I had just finished cleaning out the fuel tanks yesterday and after reinstalling them, I started up the old gal and she ran better than ever (presumably because i cleaned all the rust and byproducts of 8 year old gas out). The only thing was that i had the idle speed screw pretty far in to have it keep a decent idle. Once I brought it out today to her through the paces again, after getting her started up (took a few goes since I'm new to starting an engine with a carburetor and ended up flooding the engine) the idle fluctuated wildly. It went from being just barely idling to a good 1300+ rpm (Choke full out since it was a cold start). Since my successful idle yesterday, I didn't change a thing. The bike just sat for maybe 18 hours. After having it idle wildly for about a minute, I cut the power then attempted a to start her back up when the jackshaft lock plate snapped, causing the assembly to disassemble itself.

    If you guys can offer any help (preferable on the lockplate issue since I'm sure cleaning the carburetor and re tuning her will likely fix the idle issue) on these issues, I'd be quite grateful.

    Josh B.
    Last edited by joshua13452; 04-17-2016 at 09:28 AM.

  2. #2
    HCG Technical HCG SupporterHCG TechnicalSenior Member Relic's Avatar
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    If I remember correctly, it should be 7 ft.lbs. and use blue lock tight on the bolt. (only a drop)
    My Golf Swing is so bad, I look like a caveman killing his lunch.

  3. #3
    HCG Technical HCG SupporterHCG TechnicalSenior Member
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    interesting. i've never seen a lockplate crack or break. to me, that would mean that even secured down that the bolt wants to rotate putting force on the lock tabs. the only way that could happen is if there is movement between the jack shaft (where the bolt threads into) and the starter drive end/pinion (where the lock plate is). maybe look at that. also, is the starter bushing on the outer primary look ok? all things being equal, the problem seems to have started with the starter replacement so maybe try and retrace that and look at everything...

    the idle thing can be a number of things. as a rule, the pilot air screw should end up around 1-1/2 - 2 turns out. you sound like you are doing OK on that one. look closely at the manifold seals when you go back together.

    let us know-

    j
    Last edited by junior; 04-17-2016 at 05:14 PM.

  4. #4
    HCG Technical HCG SupporterHCG TechnicalSenior Member
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    just thought of something....

    the coupling that engages the jack shaft and starter is directional. did that get installed correctly (machined counterbore facing jackshaft)? also- there is a thrust washer between the lock plate and the pinion. did that get lost?

    j

  5. #5
    Junior Member Just broke my cherry!
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    I'm pretty sure I made sure the counter bore was facing the jackshaft. I may pull the starter just to be sure. Also there is a thrust washer inbetween the lock plate and pinion. I think you may be onto something with your theory of there being a bit of rotational play between the lock plate and bolt. I think what I'll try it using the original jackshaft bolt instead of the one that came with the starter and drip a bit of blue lock tite on the bolt to see if that helps. I'll also make sure the lock plate is as tite on the bolt as possible.
    Last edited by joshua13452; 04-18-2016 at 03:35 AM.

  6. #6
    HCG Technical HCG SupporterHCG TechnicalSenior Member
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    if you are going to pull it down anyway, i'd dry fit things on the bench first. might see something...

    j

  7. #7
    Junior Member Just broke my cherry!
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    Just pulled the starter and shaft. Everything looks good to go. Made extra sure the counterbore was facing the shaft itself. I think I also figured out that the primary is a 92 primary so I'm going to try a 92 lock plate. Not sure if the difference between the 92 and 93 are that different but i suppose their different for a reason. Once i get the new lockplate, I'll reinstall the bolt with 7-9lbs torque and a dab of blue locktite. Additionally I'm going to use the original jackshaft bolt rather than the one included with the new starter.

  8. #8
    HCG Technical HCG SupporterHCG TechnicalSenior Member
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    as i recall, there was a change to the cover design somewhere around 95-96. they are not interchangeable with later evo models, even the gaskets are different. in 1998, there was a change in the number of teeth on the starter drive pinion and clutch basket, again these parts are also not interchangeable.

    while not all of this applies to the issue at hand, i'd be sure that everything you are using is compatible. i've done a lot of mixing and matching and in the process screwed stuff up before...

    j

  9. #9
    Junior Member Just broke my cherry!
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    Quote Originally Posted by junior View Post
    as i recall, there was a change to the cover design somewhere around 95-96. they are not interchangeable with later evo models, even the gaskets are different. in 1998, there was a change in the number of teeth on the starter drive pinion and clutch basket, again these parts are also not interchangeable.

    while not all of this applies to the issue at hand, i'd be sure that everything you are using is compatible. I've done a lot of mixing and matching and in the process screwed stuff up before...

    j
    I gotcha. The only part that is not stock in the jack shaft is the lock plate. Everything else in the jack shaft, primary and related areas I haven't touched nor do i intend to mess with anything. The reason that I even replaced the original lock plate was because when i bent the lock tab to lock the bolt, it snapped.

  10. #10
    Junior Member Just broke my cherry!
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    Hello again fellas, just wanted to give a little update in case others are having the same issue.

    I have since replaced the lock plate with a 92' lock plate. The 92 lock plate seemed to be a tad thicker and the bit that goes into the keyway was a bit longer. I also torqued the bolt down a bit more than last time (About a 1/3 turn past when the starter begins to turn with the bolt by hand). So far no issues however it usually doesn't break until a good bit of use so I'll check in again if it breaks or in a few months assuming it stays together. Furthermore, I replaced the thrust washed with a new one. The old one had slight wear on the little rubber ring the the middle so I decided it would be best to replace it.

    On the topic of the crazy idle, as I suspected a simple carb cleaning did the trick. I actually found way way more than I bargained for when I took the carb apart. There was a crazy amount of trash in it and the slow jet was about half clogged. After cleaning all the jets and resetting the idle mixture screw, she's idling well.

    I will have to re tune her however. I had to reset the mixture because it was previously set way way to rich. So much that it would flood the engine which I figure contributes to why the lock plates were breaking. I had to turn the engine over way to much compared to its present state. It used to take a few goes at the starter and good goes at that (5-6 seconds on the starter). Now, about 1-2 seconds on the starter and she comes to life. Still needs to be tuned properly like I mentioned but I reckon she's much happier now. The re tuning will be done once my EZ adjust mixture screw comes in.

    Also added 5 oz of sea foam to help keep the carb clean and If my memory serves, it also helps clean carbon out carbon from the engine, valves and what have you.

    The only issue I have now is the starter kick back. I've read that its somewhat normal and wont cause damage to the starter but the noise is just plain terrifying. I don't think I've ever cringed so hard in my life. I plan on replacing the stock compensator which supposedly resolves this issue.

    Well fellas, hopefully my issues are fixed. Until next time, I leave you with a picture of the old gal.

    (Bike is a 98' Softail Custom)b409QYb.jpg
    Last edited by joshua13452; 04-28-2016 at 03:39 AM.

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