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  1. #1

    Wide mag bearing failed prematurely,Suggested bearing oil hole positioning

    I'm a newbie looking to get some good info. that I know I can get here. I have a 97' Gp1200 with a SBT rebuilt motor. Cases are 63m which may be from an older 1100. It had a bad wide style mag bearing. The mag bearing failed with very low hours. The bearing oil hole was on the bottom which cannot get oil there when indexed in the pin. The oil seal was also melted. All of the inside bearings are fine. PTO bearing failed due to oil line coming off. My case does have a slot near the seal for oil to go beside the bearing to lube. I'm wondering if this is enough to lube both rows of balls. Should I re-index the bearing to line up the oil hole with the oil hole in the case? If not, what problem should I look for?
    Thanks for everyone's help in advance.
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  2. #2
    Moderator OsideBill's Avatar
    Join Date
    Mar 2006
    United States
    The 63M cases were used for both the 1100 and 1200 motors difference being the 1200 had three pulse nipples for the carbs where the 1100 only had 1. There is a pin in the case to align the bearing properly for the oil hole, if someone assembled incorrectly the pin gets pushed up into the cases, this is a common mistake made by inexperienced assemblers. The bearing can also be installed backwards which causes the holes not to align properly.

  3. #3
    Thanks for the fast response. I looked at it closer and no matter which way the bearing is installed, the oil holes will not line up. This may be just how it gets installed and is lubricated through the front behind the seal. I just think that is a poor setup and may be why it failed. The locating pin is still raised above the case. I do have three pulse nipples,two in the #1 reed chamber and one in the #3 chamber. I have no problem re-drilling the pin location to line the holes up if that is needed. There is no evidence the pins were not seated in the bearings. Are all of the wide bearings the same throughout the 1100 motor years? I've read the 1100 bearing is better than the more expensive 1200 set-up.

    P.S. The hole near the edge of the bearing is the pin locating hole.
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    Last edited by gilley76; 03-30-2012 at 10:52 AM.

  4. #4
    Yamaha artisan Cutlass's Avatar
    Join Date
    Oct 2010
    Madison, WI, USA
    I've seen pics of people grinding little notches/grooves to help direct oil flow into bearings a little better. I think you could and should try this. Can't hurt to get a little more lube in there.

    Here's a pic of a notched oil passage:

  5. #5
    Good idea! Thanks Cutlass.

  6. #6
    I have determined that the pin location was never moved to align the older style wide mag bearing with the oil passage. I realized this when I found this pic of the narrow bearing setup. How do I remove the pin/ just grind it down and install new? Remember, I'm using the wide 1100 bearing in 98' 1200 cases.
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  7. #7
    Myself's Avatar
    Join Date
    May 2007
    North Central Arkansas
    Match it up at the case. The bearing race is very hard, I think you'd have a very tough time drilling it. Drill your case to match the pin and groove to redirect the oil if needed.

  8. #8
    SBT crank bearings have both pin locating holes for either case in the bearing from what I have seen in person so they only need to stock one crank

    when I convert 1100 to 1200's I pull the pin (heat) an re use it in the newly drilled spot in the case

    helped to have a trashed 1200 case for reference

  9. #9
    Flying Scotsman's Avatar
    Join Date
    May 2006
    I am puting an engine together.
    I have cases crank and I have a new 1100 mag bearing.
    I can either drill or grind a new pin location in the bearing case I can remove the pin and epoxy the bearing in position or remove and relocate the pin.Remove and relocate would be best but drilling or grinding a new in hole in the bearing case is easier.I am going to put a new pin hole in the bearing case so the oil galley lines up to the oil hole in the crank case.

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