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  1. #1

    Join Date
    Apr 2005
    Location
    Upstate NY
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    37

    Recommendations on top end rebuild for a 787

    I while back I picked up a cheap spare and running 787 motor that will need work, the front cylinder is about 20 psi down. I pulled the RAVE valves today and I can see a little scoring on the front piston. The crank seems tight so I want to start with a top end rebuild and take it from there. What do you guys recommend? .25mm over bore if thats all thats needed. How about pistons? I see many WSM teflon coated kits on ebay, and even one company that does it all for about $300.00 (send your jugs and they bore them and raves and send them back with sized pistons). I am concerned about cheap chinese metals. Is OEM the best way to go? This will be my first top end rebuild, id like to learn and do it right. What kind of specialty tools are involved? I'd like to do everything besides the overbore in my garage. Thanks!

    Silas


  2. #2

    Join Date
    Jul 2008
    Location
    Southeast Texas
    Posts
    101
    You are going to get alot of opinions on this, so here's mine. If it's worth rebuilding, then it's worth using quality parts. I only use genuine Rotax parts in my rebuilds. They are not the least expensive, but, I have never had a part fail because of quality.
    Robert

  3. #3
    flyin' the friendly skies airbornexp's Avatar
    Join Date
    Aug 2007
    Location
    Mahomet, Il. USA
    Posts
    6,004
    +1
    163
    a top end is easy. all you need is a basic socket kit (metric) a pair of needle nose pliers for the snap ring for the wrist pins. the hard part is getting the rings on right and holding them while trying to put the cylinder on....oh and not tearing the base gasket. make sure that you get off all the old gasket. I used a light wire wheel to get it nice and clean. you may not have to bore .25 over if it isnt that bad. you may need a light hone. I went with Pro-X pistons but you will find others that like WSM's and OEM's If its a stock motor I dont think that any one makes a difference. the teflon coating lasts for basically the first startup for cylinder wall protection then its gone pretty quick.

  4. #4

    Join Date
    Apr 2005
    Location
    Upstate NY
    Posts
    37
    Thanks guys. Ill pull the motor apart tonight and let you know what I find.

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