Results 1 to 5 of 5

Thread: Different size bored out 550 cylinders

  1. #1
    New member
    Join Date
    Aug 2007
    Posts
    10

    Default Different size bored out 550 cylinders

    I sent my cylinders to Napa/Polaris in Barrow to have them bored out to a bigger size due to damage to one side cylinder and very minor damage to the other. Assuming the mechanic would bore them out each to the same exact size, he instead bored out one to .025" over and the other cylinder to .050" over. Is that an okay thing to do? And why didn't he just bore them out to the same sizes? Can that throw off crankshaft balance with different weight pistons or is it too minor? I wished he (mechanic) bored them the same size because the labor alone cost me $400.00

  2. #2
    Member AKDoug's Avatar
    Join Date
    Apr 2006
    Location
    Talkeetna
    Posts
    5,714

    Default

    It shouldn't be too big of a deal. I have run pistons of different sizes in machines before when I was too broke to pay to do each cylinder. What type of 550 was this? $400 is way too much to bore and hone a cast iron cylinder, but a good price for boring and recoating a Nikasil cylinder.

  3. #3
    New member
    Join Date
    Aug 2007
    Posts
    10

    Default

    $400 is way too much. They were just regular stock cylinders from my 2006 550 Trail Touring (Edge). I don't understand that guy - If he charged me that much he should have just did them both the same. And the coating from the SPI pistons are already scratched from his look like poor job. I'm just afraid of blowing the engine again from a poor job with a hefty price tag.

  4. #4
    Member AKDoug's Avatar
    Join Date
    Apr 2006
    Location
    Talkeetna
    Posts
    5,714

    Default

    The SPI coating is pretty fragile anyways. You have to be pretty careful installing them to keep from scratching the coating. The piston skirts shouldn't rub on the cylinders so the coating shouldn't get worn. Did the machinist have the pistons on hand when he bored the cylinders? There should be about .004" of clearance from the piston to cylinder.

  5. #5
    Member
    Join Date
    May 2011
    Location
    Wasilla
    Posts
    22

    Default

    Won't be any problem at all. I have a boat motor with 1 stock cylinder - 1 bored out 0.025" over. I lost one cylinder, bored it over and left the other stock. Put new rings on the stock size when I rebuilt and have been running it for 10 years now. You won't know the difference.

Bookmarks

Posting Permissions

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