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anyone swap out those annoying allen head and jis screws with a more modern design?

Discussion in 'XJ Technical Chat' started by squidx85, Jul 9, 2019.

  1. squidx85

    squidx85 Member

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    As I was looking at my bike again today, I noticed the majority of phillips (JIS) screws on my carbs are chewed up, they're not even the right ones, and I wondered if anyone had swapped them out with screws of a more modern design.

    For anyone reading this who doesn't know what I'm getting at, say you're building a deck at your house. With phillips or square drive heads, the torque required to drive the screw is so close to the limit of what that style can handle, you'll end up stripping screw heads out frequently. With a T25 torx head, the design can handle enough torque to actually break the screw shank, and the result is you can drive boxes of T25 torx head screws without stripping a single one.

    My 85 maxim x also has allen head bolts on it, I'm definitely not a fan of those either.

    I believe the highest torque capacity design for a bolt or screw is an external drive, like what a 12 point socket fits over, not an internal spline like a torx head. I just mentioned the T25 torx head deck screws because they're the best design for that particular application.

    Anyway, I'll probably end up replacing the JIS head screws with something else if I can find it, I just figured I'd ask here to see if any of you guys have done that too.
     
  2. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    The problem isn't with the screw, it's with the screwdriver.
    JIS drivers don't chew up the heads. Phillips is not JIS. They are different standards with different engagement angles.
    Overtorquing a screw in wood is one thing (also use self-drilling screws, or drill pilot holes so the heads don't get chewed up). Overtorquing a screw in a mechanical assembly can be expensive.

    Having said that, the screws on my carbs have been replaced with Allen-head screws. Most of the other JIS screws are original, and undamaged.
     
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  3. firebane

    firebane Active Member

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    JIS is modern. The problem is people use the wrong drivers and mess em up.

    JIS is better than normal phillips and there is nothing wrong with allen head bolts either.

    Again.. you need to use the proper tools. Also the majority of bolts on a bike are low torque yield that hand tight plus a bit is fine.
     
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  4. Polock

    Polock Well-Known Member

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    i replaced all mine with ss allen heads. if you use hex head bolts you might not get a socket on them, there isn't enough room.
    how tight do you think they need to be? a ss allen head screw can strip any thread in these carbs
     
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  5. squidx85

    squidx85 Member

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    Me personally, I use the right tools and procedures, because then the liability is on the engineers, and they usually do a decent enough job. But my bike is old, and things have evolved, don't modern japanese bikes use hex and torx head screws? Since my screws are already all chewed up by whoever worked on it before I bought it, I figure I might as well replace them with a better design anyway. I googled something like "do modern japanese bikes still use jis screws" and read some interesting stuff. Most people were saying they don't anymore, and one guy was saying that within the last 10 years all good quality (snap on, etc) phillips screwdrivers have gone to JIS specs, so there's no difference anymore. I did not know that, and haven't checked it out yet, but another guy confirmed it in that thread. The guys were also not only criticizing the design of the JIS heads, they were criticizing the material quality too, saying they're made of "butter", and that they've replaced them with allen/hex head screws. I think I'll call up fastenal and see what they have, as long as they don't want to charge me $5 a screw or something ridiculous like that.
     
  6. firebane

    firebane Active Member

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    JIS screws have ALWAYS been soft and why its so damn critical to use the proper driver on it. People end up chewing JIS screws because of the sheer fact they get a screw driver that isn't JIS and go to down and destroy it.

    The other problem is that the material the screws are made of and the casings are made of are two different metals generally so they meld and this is why a impact driver on a old bike is also key to ensuring things don't get destroyed.

    People think working on these old japanese bikes can be done with general hand tools and for the most part they can, but on the other hand they need special tools to do it properly.
     
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  7. squidx85

    squidx85 Member

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    One technique I've used many times before with screws on cars (like say an intake air temp sensor on an civic or integra) is to take a short bit that fits into the screw head, hold it with a vise grip, and whack it with a small, lightweight hammer. That would almost always break it loose, and I'd be able to unscrew it without any damage. But at the same time I always thought they should have used an 8mm or whatever size socket head screw, then you wouldn't have to use mechanic jiu jitsu to get them loose.

    I just called fastenal and the girl told me they don't sell to the general public at their stores anymore, you need to have a business account. Talk about an absolutely moronic policy. But she said they still do sell to the public on their website.
     
  8. Polock

    Polock Well-Known Member

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    i use McMaster Carr but you buy a bag to get the 4 or 5 you need. i'm to the point now where i can sell screws. it's nice to be able to not even look for the one you drop, just get another one
     
  9. Simmy

    Simmy Well-Known Member

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    Get yourself one of these from Motion Pro.
    I can really lean my weight into this, as long as the fastener has not been buggered up before I can break it loose.

    38120049.jpg
     
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  10. squidx85

    squidx85 Member

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    Maybe I will look up mcmaster carr. I just checked the oem screw prices where I got my airbox boots, yamahapartshouse, and it's $120 shipped for the 16 screws on top of the carbs, and the 16 ones holding the little metal bars that hold the carbs in line. Ridiculous.

    That motion pro tool does look good.
     
  11. Chitwood

    Chitwood Well-Known Member

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    Can confirm on the motion pro tool. Best money I have ever spent for my Yamaha(s). Even some partially messed up fasteners have come right out using this tool in the proper way.
     
  12. Jetfixer

    Jetfixer Well-Known Member

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    Check upper right corner of page XJ4Ever , will have what your looking for ...as to fastners ....Look at Fastenal or Sears Hardware or Ace hardware , I did all my fastners on my carbs with stainless steel ...think I spent 20$ all metric .
     
  13. Ryengoth

    Ryengoth Active Member Premium Member

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  14. XJ550H

    XJ550H Well-Known Member Premium Member

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    how are their shipping prices?
     
  15. Ryengoth

    Ryengoth Active Member Premium Member

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    Decent and upfront. I usually buy in bulk for sizes I use a lot or get the kits. They have really nice divided boxes, thick plastic. I end up reusing them and refilling them.
     
  16. Polock

    Polock Well-Known Member

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    where do i get torx heads
     
  17. XJ550H

    XJ550H Well-Known Member Premium Member

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  18. XJ550H

    XJ550H Well-Known Member Premium Member

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    do metric screws come as jis or are they phillpis?
     
  19. Ryengoth

    Ryengoth Active Member Premium Member

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  20. Ryengoth

    Ryengoth Active Member Premium Member

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    I believe you can get both. Would have to look. I usually just get the phillips.
     

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