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Acceleration Noise/Vibration

Discussion in 'XJ Technical Chat' started by sybe, Aug 3, 2020.

  1. sybe

    sybe Active Member

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    I am getting concerned about a thumping/clunking noise coming from the rear and its either the drive shaft or the pumpkin. When i accelerate from a stop or a quick acceleration while rolling i hear and feel a thump/clunk. XJ 650's have that horrible hard shift noise at times and i dont know if this sound is normal. The rear pumpkin has oil... doesn't leak and seems ok.

    Could the sound and feeling come from the engine and am feeling it in the rear??? Do the knuckles on the shaft go bad?
     
  2. Toomanybikes

    Toomanybikes Well-Known Member

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    There is a ramp damper and when the spring gets older and weaker it will do that under harder launches my Xj750rl and xj650rjc do the same thing
     
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  3. tx1

    tx1 New Member

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    I had the compression spring snap on mine ( located in the hub and connects to the driveshaft) and had a clunk and the frame vibrates when you turn the rear wheel by hand feels like a tight spot when rotating the rear wheel.
     

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    Last edited: Aug 3, 2020
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  4. sybe

    sybe Active Member

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    If is there any way to fix it or its just normal on an old bike? its a little unsettling when you merge onto the highway or take off at a redlight.
     
  5. tx1

    tx1 New Member

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    Yes its a cheap fix take the back wheel off remove the hub 4 17 mm nuts and replace the spring becare full with the hub it will leak oil if tilted the wrong way just over an hour to do the job .
     
  6. sybe

    sybe Active Member

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    Thanks for the info. I am guessing this is the spring 90501-16491-00. is there anything else i should pay attention to that might be the culprit?
     
  7. tx1

    tx1 New Member

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    Yes, that is the correct part number and only at the other end of the shaft is the UJ coupling if the spring doesn't do the job that will be the next thing to check for wear and removing the complete swinging arm to do so if you go that far you might as well replace the swinging arm bearings while it is off the bike.
    20200803_184538-1.jpg
     

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  8. sybe

    sybe Active Member

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    we are getting ready to move out of Brooklyn and near goldens bridge. so this will be my first project in the new garage!
     
  9. tx1

    tx1 New Member

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    Bit of an update here chaps anyway replaced the compression spring and replaced the oil seal on the driveshaft and put it all back on the bike anyway set to go out on a ride went to take off and a bad noise from the driveshaft again a clinking sound, pushed it back in the garage and got round to stripping it today [​IMG]and guess what I found this time upload_2020-9-15_15-34-20.png upload_2020-9-15_15-34-20.png upload_2020-9-15_15-41-45.png
    The shaft between parts 10 and 11 had snapped not sure what you would call that shaft but the bike did still have drive my question now is can that shaft be removed or would it be just as easy to change the drive hub over and what hub to go for. upload_2020-9-15_15-34-20.png upload_2020-9-15_15-41-45.png upload_2020-9-15_15-34-20.png upload_2020-9-15_15-41-45.png Thanks for any help you can offer
     
  10. Franz

    Franz Well-Known Member

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    I would get a used unit off E Bay.
     
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  11. tx1

    tx1 New Member

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    Thanks for the reply are all the units the same my bike is a 1980 xj650 euro model.
     
  12. Franz

    Franz Well-Known Member

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    I am not sure to be honest. Someone will know on this forum.
     
  13. Toomanybikes

    Toomanybikes Well-Known Member

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    All the rear drive units the same on 650 and 750.
     
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  14. tx1

    tx1 New Member

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    Thanks for the advice have managed to obtain a 650 turbo one over here off ❌b❌y for £30.00 hope to soon be back on the road before the bad weather gets here
     
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  15. bigfitz52

    bigfitz52 Well-Known Member

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    the 650 Turbo unit may be different in some way. Virtually all the 650s and 750s including some 700 and 750 Virago models list 5G2-46101-01-00 as the part number for the whole "pumpkin" assembly; the Turbo shows a way different part number.

    I have absolutely no idea what the difference might be, just be aware they are different than the others. One might suspect final drive gearing? Maybe ask Chacal?
     
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  16. Simmy

    Simmy Well-Known Member

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    they are painted black.
     
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  17. bigfitz52

    bigfitz52 Well-Known Member

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    There is likely a bit more to it. Yamaha part numbers follow a distinct pattern; "finish" differences, such as black vs. polished or natural, etc., are covered by the last two digits of a part number; whereas the first three are the "family" of the bike the part originated with. So for instance, Yamaha used the same fender for the Seca 650 and Seca 550s, it carried a "4K0" part number prefix (the original Euro XJ650) all along, with only the final two digits in the part number indicating the color or finish.

    In this case, the turbo pumpkin carries a 16G part number prefix (650 Turbo) whereas all of the naturally aspirated bikes use the 5G2 part. There is more to it than what color it is painted.
     
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  18. bigfitz52

    bigfitz52 Well-Known Member

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    I may have found the difference, in an extensive review of the 650 Turbo when it came out: "the final drive now has a rubber shock cushion to ease the peak loads applied at the rear wheel." Whether this affects interchangeability I do not know. But it may explain the part number difference.
     
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  19. Simmy

    Simmy Well-Known Member

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    The Turbo has rubber cush drive parts in the rear wheel between the spline and the wheel.
    The standard Seca is rigid here.
    I have the RJ pumpkin on my Turbo now but I've only done 8 kms like this.
     
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  20. Simmy

    Simmy Well-Known Member

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    Although this shows the brake side, you can see the rubber inserts on the Turbo wheel on the left
    IMG_1313.jpg IMG_1313.jpg
     
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