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Thread: 1997 R850R Solving Vibration and Cat Code Plug Change

  1. #16
    MOA #24991 Pauls1150's Avatar
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    The original wires aren't shielded, just loosely jacketed. (confirmations or rebuttals welcome)

    I've been mulling this over for a while...
    I don't "Know", but it may be wrong to use shielded wiring in this application: Shielding a wire adds to its capacitance, which reduces its higher-frequency response. The pickups are intended to send a pulse to the ignition controller; losing the higher-frequency response would "round off" the rising and falling edges of this pulse, which may affect the timing of this signal to the computer; it would also reduce the total energy in this pulse.

    Maybe it doesn't matter...

  2. #17
    Neglected Bike Adopter
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    Quote Originally Posted by Pauls1150 View Post
    The original wires aren't shielded, just loosely jacketed. (confirmations or rebuttals welcome)

    I've been mulling this over for a while...
    I don't "Know", but it may be wrong to use shielded wiring in this application: Shielding a wire adds to its capacitance, which reduces its higher-frequency response. The pickups are intended to send a pulse to the ignition controller; losing the higher-frequency response would "round off" the rising and falling edges of this pulse, which may affect the timing of this signal to the computer; it would also reduce the total energy in this pulse.

    Maybe it doesn't matter...
    I picked shielded wire because another much older thread on here mentioned a part number to find, but also, on my bike, the original wire harness is shielded. The shielding is exactly what I'm familiar with seeing on shielded computer cables; it is also directly soldered/crimped to the fifth pin in the Hall Sensor plug at the one end, which I think is a ground.
    I imagine it can't hurt that much to have the new wire shielded like the original and I did plan on attaching it to that ground pin like it was at the factory.
    Owner of the saddest 1997 R850R you ever did see.

  3. #18
    MOA #24991 Pauls1150's Avatar
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    Ah, OK - thanks for the clarification!

    Paul S

  4. #19
    Neglected Bike Adopter
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    Just for the curious, here are a couple pictures of my previous Hall Sensor repair. At the time I was simply improvising with what I had, which worked to get the bike running again. The only issue is that it's not waterproof. The foil tape is high-temperature tape from an auto parts store, the wiring is silicone-jacketed (which is supposedly good up to 200C) and the electrical tape is Scotch Super 33+ which is also high-temperature, at least for rubber electrical tape.

    I'm undoing these repairs and replacing them with a shielded 4-wire conductor and marine adhesive-lined heat shrink tubing. Pics to follow once I'm done with that.

    IMG_20210911_1455572.jpgIMG_20210911_1455409.jpg
    Owner of the saddest 1997 R850R you ever did see.

  5. #20
    Fortis Fortuna Adiuvat Omega Man's Avatar
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    GSAddict to the white courtesy phone.
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  6. #21
    Left Coast Rider
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    Quote Originally Posted by senseamidmadness View Post
    Just for the curious, here are a couple pictures of my previous Hall Sensor repair.
    Ugh....

    Please refer to Post #12 and #20in this thread.
    Last edited by BC1100S; 09-12-2021 at 03:52 AM.

  7. #22
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    Since you are recoiling in collective horror, I would like to emphasize that the original repair was a temporary solution just to get the bike running for a while, with known-improper materials. I promise my solder joints look much better than the outside would suggest. My soldering experience is far more in the area of printed circuit boards and I'm still learning proper finishing work on automotive wiring harnesses.

    This is the improved repair with the correct PTFE-jacketed wire and heat shrink tubing. I just reinstalled it and the bike started up fine. I made one mistake during the reassembly and am not 100 percent sure that the waterproofing of this repair is perfect, but it is certainly much better than it was.

    IMG_20210911_1944480.jpgIMG_20210911_1944553.jpg

    Unrelated, but when I went to put the sensor back in a squirrel had stuffed a half-eaten piece of pepperoni pizza between the Telelever and the engine case! Wish I had gotten a picture of that.
    Last edited by senseamidmadness; 09-12-2021 at 05:27 AM.
    Owner of the saddest 1997 R850R you ever did see.

  8. #23
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    Well, that looks MUCH better.

    And...you're going to have one pissed off squirrel on your hands.

  9. #24
    Fortis Fortuna Adiuvat Omega Man's Avatar
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    Squirrels can be problematic- this shot, see the orange glow of the fire, was from the this morning. For the third time this year, a squirrel wanted to see if it was faster than the speed of light. 4400v leaves them wishing they had skipped trying-

    62A37D3F-8B10-4097-A3E4-7EEAA82B4524.jpg

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  10. #25
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    Quote Originally Posted by Omega Man View Post
    Squirrels can be problematic- this shot, see the orange glow of the fire, was from the this morning.
    Lunch?

  11. #26
    Fortis Fortuna Adiuvat Omega Man's Avatar
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    Quote Originally Posted by BC1100S View Post
    Lunch?
    Just one……..so- snack
    om
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  12. #27
    MOA #24991 Pauls1150's Avatar
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    Get it while it's fresh!
    At least the prior squirrel tried to keep it warm for later.

  13. #28
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    I think by tossing the pizza just a few feet away instead of throwing it in the trash I may have evaded the squirrel's wrath.

    Helps that I fled the scene before it showed up.

    On a non-squirrel related topic, the new spark plug wires and Hall sensor repair didn't do anything for my bike's vibration. It was okay when it first started up, but it's back to as buzzy as ever. I think the Motronic started out richer and then leaned out again.
    At this point I'm thinking it could be a wonky O2 sensor making the bike run just a bit too lean, or maybe my particular bike is just this way. When I buy an AF-XIED it should smooth it out, and just to be safe I'm going to buy a new oxygen sensor at the same time.

    I suppose I could still check diligently for vacuum leaks on either intake side but I'm not sure I'll find anything, since I replaced all the rubber parts. I'll spray a bit of something volatile near the intakes while it's running and see what happens.
    Owner of the saddest 1997 R850R you ever did see.

  14. #29
    #13338 PGlaves's Avatar
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    Quote Originally Posted by senseamidmadness View Post
    On a non-squirrel related topic, the new spark plug wires and Hall sensor repair didn't do anything for my bike's vibration. It was okay when it first started up, but it's back to as buzzy as ever. I think the Motronic started out richer and then leaned out again.
    OK Back in my Bench Wrenching column I wrote about imbalance and vibration and made a big distinction between "combustion imbalance" and "mechanical imbalance.:

    At this, point having followed this thread, I am convinced you have a mechanical imbalance: probably an improperly installed clutch pack.

    Combustion imbalance will ONLY cause a vibration when one cylinder is affected and the other is not. So the Motronic, and any other fuel related cause other than a bad injector ought to cause the problem in both; not just one cylinder.

    Valves? Throttle bodies? Plugs? Wires? Coils?

    If all OK it is not combustion related. So is it a mechanical imbalance?? I have my suspicions!
    Paul Glaves - "Big Bend", Texas U.S.A
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  15. #30
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    Well the trouble is that when I pulled my cat code plug entirely, and the fueling actually went open-loop, the engine was significantly smoothed out. Exactly as people describe what it's supposed to be like -- it was so smooth I could no longer tell what RPM the engine was at by feel and had to tell by sound.

    If I had a clutch pack imbalance, I still would've been able to feel vibration at that point, right?
    Owner of the saddest 1997 R850R you ever did see.

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