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  1. #1
    Prism's Avatar
    Join Date
    May 2007
    "New" Jersey

    WATCH OUT on replated jugs

    So I put my 1300 back together with a fresh top end and Millennium replated jug. Everything went together fine. I Did my break in procedure, checked the compression and everything was perfect. I fine tuned the engine with my EFI controller until I had good idle and low speed resopnse, then I leaned out the top until I lost RPM then backed up a hair. Perfect. Finally I came upon the 10 hour mark. This is when I pull the head and check the wash to make sure my plug and RPM readings jive with the piston tops. Well, to my surprise I found the begining signs of a problem with the replated cylinder. There was some light scoring in one concentrated area that was not inline with a transfer, intake, or exhaust port. At first glance I thought a piece of junk may have been in the cylinder from assembly. This was unusual because I am pretty anal about clean assembly practices. Upon closer inspection, I saw some very light galling or aluminium transfer from the piston and at that point I yanked the jug. Yep, the piston had a nice shinny spot on the skirt at the 4 o'clock position. (arrow facing you looking down from above) WTF! After looking at everything, I noticed a couple of drops of water on top of the 2 stroke oil in the crankcase. I know I didn't injest any water and no one else had used the ski, so where the ?#@! did this water come from? I then looked carefully at the base gasket and when I pinched the gasket, water emerged from the layers. Further investigation lead me to the water jacket at the base of the jug. It was there I found my answer. Before anyone replates a jug, they wash them in a caustic solution. This solution removes EVERYTHING. Paint, dirt, grease, etc. It also removes any casting sand that is hiding in hard to reach places. It works very well. The down side is it leaves a sandblasted texture everywhere, and can sometimes open up pores in the aluminium, including on the sealing surface. This usually isn't a problem with a traditional gasket, but the metal shim gaskets Yamaha uses need the surface to be perfectly clean and flat. In my case it was not the sand blasted texture that caused the problem, the cleaning solution erroded the metal around the water jacket and caused a pit to open up exactly in the sealing area of the gasket. Under idle & part throttle it probably didn't leak much, but at WOT it certainly did. This washed the oil from the piston in that one area and caused the localized galling. If putting a replated jug back in service, I would never reuse a gasket. The thin rubberized layer on an unused gasket will have a hard enough time trying to seal that sand blasted texture let alone a used gasket... even with sealer. Be on the lookout for this kind of stuff when you get a replated cylinder back. I'm glad I found it before anything major happened or it could have been really bad! Hope this saves a few headaches!!

  2. #2
    txgp1300r's Avatar
    Join Date
    Apr 2006
    Dallas , Texas
    Good post , I always put some 1211 on the base gasket's even when new.

  3. #3
    Hydrotoys's Avatar
    Join Date
    Jul 2005
    Mesa, AZ
    I know it's possible to put the base gasket on upside down as well... not related to your issue, but it does happen.

  4. #4
    Moderator OsideBill's Avatar
    Join Date
    Mar 2006
    United States
    The area of concern here was pointed out to me by Lowell on the first motor I did with him. The problem with this area is it has poor circulation here and is more susceptible to corrosion, the acid cleaning during the stripping process for re-plate removes the corrosion leaving a void. Lowell recommended that I wipe a thin layer of 1211 or Yamabond on it to fill the voids. I did this and allowed it to cure then did my normal sealing process.
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  5. #5
    XL1200Ltd-Keith's Avatar
    Join Date
    Aug 2005
    Group K has the same advise about using a thin layer of 1211 to take care of this.

  6. #6
    TX21's Avatar
    Join Date
    May 2007
    North Texas
    Can you reuse the head gaskets? I need to pull my head if so and have a look. Its been about 10hours since my rebuild.

  7. #7
    Moderator beerdart's Avatar
    Join Date
    Aug 2006
    For Fenn the search inept.

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