Results 1 to 3 of 3
  1. #1
    rxpredviper's Avatar
    Join Date
    Feb 2009
    Location
    WPB
    Posts
    2,248
    +1
    62

    crank bearings. ????????

    Some one please tell me why crank bearings the bottom ones dont have a oil chanel for oil to travel ..everytime I open and motorr the bottom bearings are shot ..I'm thinking about following the top one to the bottom same as top is this a good idea or a bad one ..explain please


  2. #2
    Sanfish's Avatar
    Join Date
    Jun 2014
    Location
    S/E Florida
    Posts
    2,540
    +1
    778
    The reason for the oil groove on only half the bearing is to allow even oil distribution the moment it exits the oil hole. Once it hits the crank (and builds psi), the crank is then on a cushion of oil so the bottom bearing doesn't need the groove. Also, the other reason why the lower bearing is without groove is because those are under extreme stress from the combustion forces wanting to push crank away from block. If the lowers had grooves, there would be less surface area and much faster wear.

    If you have unusually high lower bearing wear, it could be due to fatigued (worn out) main bolts/studs. Could also be caused from an out of spec crank. And if you ever overheated the motor, the block may need to be line-bored. There are MANY tell-tale signs to look for.

    Post a picture of the bearings and I'll try to help.

  3. +1 by:


  4. #3
    rxpredviper's Avatar
    Join Date
    Feb 2009
    Location
    WPB
    Posts
    2,248
    +1
    62
    Thank you alot i will postpic later

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. 1100 Crankshaft (PTO SIDE) crank bearing installation
    By bnovak in forum Yamaha Old School Skis
    Replies: 12
    Last Post: 10-22-2007, 06:38 PM
  2. Hot Rods Cranks - bearings are replaceable, right?
    By bnovak in forum Yamaha PWC Performance (2-stroke)
    Replies: 1
    Last Post: 10-07-2007, 11:51 PM
  3. crank bearing
    By Cdoo EtR in forum Yamaha PWC Performance (2-stroke)
    Replies: 6
    Last Post: 04-27-2007, 04:07 PM
  4. X45 crank bearing smoked
    By WFO in forum Polaris PWC Performance
    Replies: 15
    Last Post: 10-31-2006, 07:55 PM
  5. Lost Crank Bearing on my 1300
    By JKR1300 in forum Yamaha PWC Performance (2-stroke)
    Replies: 17
    Last Post: 10-12-2006, 10:41 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •