91 Fxr

Discussion in 'FXR Models' started by fdrdr1, Nov 2, 2008.

  1. fdrdr1

    fdrdr1 Member

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    1991 FXR - need help with knock from primary. When I let off the throttle I can hear a knock from the primary. When I jump back on the throttle the knock goes away. Let off and I get the knock, pull in the clutch, it goes away. Check the chain and it is adjusted right on. I am getting ready to pull the primary and check the compensator bolt. Any other ideas when I am in there. THX
     

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  2. glider

    glider Veteran Member

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    While you're in there check the rotor splines and make sure it's tight on the shaft.
     
  3. fdrdr1

    fdrdr1 Member

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    Hey Glider,

    If I fabricate something to insert between the sprockets, will I be able to torque down that compensator nut? I have seen your posts advising against an impact wrench, so I figure I can tighten it with a cheater bar. Thanks
     
  4. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

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    Yes. Do not use an impact wrench. You should have a torque wrench to check the torque on that nut. I think it is around 150 ft-lbs.

    TQ
     
  5. glider

    glider Veteran Member

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    Yes, there's a tool available to lock the sprockets up or you can fab one up with something that will not do any damage.
     
  6. fdrdr1

    fdrdr1 Member

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    Well I pulled the primary and the compensator bolt was tight to spec. I am not sure what to proceed to next unless I remove the sprocket/assembly. Any advice - Thx
     
  7. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

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    If you still have it open, see if you can get the rotor to wobble any by alternately pushing on opposite sides of it. If not, then it is probably OK, but it is hard to see with the compensator and chain in the way.

    You said the chain tensioner is adjusted correctly?

    Does your clutch basket have slots in it so that you can see the friction plates? Nothing obvious that you can see in the clutch basket? And the cluth nut (lefty) is torqued too, right? I think that is around 70 ft-lbs (check the book).

    If everything looks good, then button it all back up, add some Formula Plus or Spectro Primary (a quart) to the case and run it.

    Sound still there?

    TQ
     
    Last edited: Nov 5, 2008
  8. fdrdr1

    fdrdr1 Member

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    TQ,
    Everything is buttoned up but I will pull the primary again - will check the clutch basket bolt and look for any rotor wabble. The tension on the chain is within HD manual spec (5/8 - 7/8 cold) but more at the upper end of 7/8 in. Just strange though, when I let off the throttle you get the knock, throttle up or pull the clutch it goes away. It clearly sounds like it is coming from the primary though and may be worth a chain adjustment closer to the 5/8 that HD says.
    Thx
     
  9. glider

    glider Veteran Member

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    How about the trans pulley or rear pulley?
     
  10. fdrdr1

    fdrdr1 Member

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    Well after about a month of research and checking everything I can through the primary I cleaned and re-torqued with no success. The comp sprocket assembly looked good, the clutch basket looked good also. The chain is adjusted properly but I am still gettin a knock when off throttle. No problem at idle, plenty of power/torque while ridin and when I accelerate or pull the clutch in the knock disappears. It was mentioned in a previous reply to look for rotor wobble - I did notice that the rotor did wobble after the comp assemble was removed and I was able to remove the rotor with some effort but without a puller. Not sure what to check next. Any ideas? Thanks - 91 FXR