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Thread: Sorry....Another 300r question

  1. #16
    gimmeamidget is offline At The Back Of The Pack Arm chair racerAt the back of the pack
    Join Date
    Jun 2014
    Location
    utah
    --
    434
    Ok thanks for the tip!

  2. #17
    Join Date
    Jan 2007
    Location
    Oceanside, CA
    --
    88
    Quote Originally Posted by Red Rider View Post
    This makes no sense to me. Why wouldn't the entire sleeve be replaced?
    As far as I was told by the shop that did my sleeve, the 85/86 R iron bores are not pressed in in the conventional sense. The are slightly bowed in the middle and the jug is apparently cast around it. This guy may be mistaken, but he's been in the small engine/2-stroke game since the 70s and I have no reason to not trust him. Any debate to the statement can be taken up with him. I am just repeating what I was told.

  3. #18
    Join Date
    Jul 2019
    Location
    Shelton
    --
    96
    That is correct most sleeves are cast in place from the factory and then finish bored/honed so there is no guarantee the bore and the OD of the sleeve are perfectly concentric, so if you had to machine out the sleeve you may and up with a sliver of iron on one side and no sleeve on the other. The new sleeves are usually put in with several thousandths press fit depending on size and the cylinder is heated in an oven and sleeve goes in the freezer, and then drop them together. 2 strokes are tough cause you have about 2 seconds for it to drop together and rotate to line up the ports before it freezes in place. I usually put the sleeve in an upside down lathe chuck on the bench, and drop the cylinder down on the sleeve while looking at the exhaust port/bridge to make sure it is lined up.

  4. #19
    207wheelin is offline At The Back Of The Pack Arm chair racerFirst time rider
    Join Date
    Mar 2019
    Location
    Northern Maine
    --
    150
    Quote Originally Posted by ATC200X4716 View Post
    That is correct most sleeves are cast in place from the factory and then finish bored/honed so there is no guarantee the bore and the OD of the sleeve are perfectly concentric, so if you had to machine out the sleeve you may and up with a sliver of iron on one side and no sleeve on the other. The new sleeves are usually put in with several thousandths press fit depending on size and the cylinder is heated in an oven and sleeve goes in the freezer, and then drop them together. 2 strokes are tough cause you have about 2 seconds for it to drop together and rotate to line up the ports before it freezes in place. I usually put the sleeve in an upside down lathe chuck on the bench, and drop the cylinder down on the sleeve while looking at the exhaust port/bridge to make sure it is lined up.
    Always wondered about this process. Hard to find places around here to do this type of work.nowadays. Lots of the old school shops have closed and in the last few years the machine work I have had done was not satisfactory.
    Take care
    207

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