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Thread: Crank case damage , what to do?

  1. #1
    apriliaforum Member SaltyBill's Avatar
    Join Date
    Nov 2018

    Crank case damage , what to do?

    Hi guys
    Im still waiting for parts to arrive before i put the engine back together. In the meantime i have been looking at all the parts, and i have noticed a fair bit of damage on the crankcase surfaces , Before i pulled her apart, there was no leaks or oil mixing with water. So it was sealed.

    I was just wondering what would you guys do in my situation. Should i just seal it back up when my parts arrive? Or should i grind the surfaces back. My heads are very good ,just the crankcase...
    I have attached the photos of all the damage.
    Click image for larger version. 

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    Im wondering how these parts get damaged like this. Its almost like the person who rebuilt it was blind or drunk.... Or is it normal wear and tear.

  2. #2
    apriliaforum Member
    Join Date
    Sep 2016
    There has to be drugs involved!
    Makes me wonder why it needs a rebuild?

    If the person was unable to disassemble the cases and covers without serious scuffing like this, what about the rest and why did it get rebuilt in the first place.
    Take a good look at the rest so you don't end up with missing parts, damaged threads, known or unknown, it's better to be sure before it is put back.

    As to the damage, there is only one permanent fix, and that is to weld things back and have them flattened. I don't know about jb weld, but that could be an option but I've never used it.
    Other than that, it's a gamble really. If it didn't leak before, it might or might not do it this time. It's really difficult to see the height differences of the damage on pictures.

  3. #3
    apriliaforum Junkie undergrounder's Avatar
    Join Date
    May 2015
    My guess is that those cases where sold used and then shipped.
    And that it is shipping damage from bad packaging or the lack of it.
    My bike is my gym, my wheelchair and my church all in one. I'd like to ride my bike all day long but I've got this thing called a job that keeps getting in the way.

  4. #4
    apriliaforum expert riot's Avatar
    Join Date
    May 2014
    One or two of those spots is corrosion. Agree on the shipping damage though.

    It is hard to tell from the pics, but most of those surfaces look like the 'external' surfaces facing the magnesium covers, which should all have gaskets, and moreover will not cause any binding/interference if they are smoothed slightly.

    Personally, I would just use a surface plate to sand them as flat as possible without removing too much material. A dab black sealant should finish the job.

  5. #5
    apriliaforum Member
    Join Date
    Jul 2013
    San Diego, CA
    I agree with wackenss. Inspect other mated parts to see if there happens to be any further damage.

    Is this the first time you’ve taken the case apart?
    Did you recently purchase it?

    If you have the previous owner’s contact then you can inquire with them who worked on the engine.

    Likely no recourse but at least you may get some info then scour the rest of the bike for poor maintenance.
    Current Stable:
    Left the Stable:
    2008 Ducati 1098 2002 Honda RC51
    2004 Aprilia Tuono 2009 Husqvarna SM610

    2004 Suzuki GSXR 750 track bike (RIP)
    2000 Yamaha R1
    1993 Suzuki Katana 750

  6. #6
    apriliaforum Member SaltyBill's Avatar
    Join Date
    Nov 2018
    This is the first time i have taken the case apart. I have only rode it 5 times. Its been a bitch to start and keep it from not stalling constantly.
    I purchased it late last year from an italian dealer in Milan. I cannot speak Italian and they do not speak english so calling to find out who worked on it would be difficult to say the least.
    All this because of the shredded starter gear, from the damaged sprag. ( i needed to check if i had metal in the oil pump)..
    I am glad i did open it as my crank bushings where toast, and a piece of piston was sitting on the bottom of the case.
    I just want to do the best i can before putting it back together.

    I will get a glass panel, some sandpaper and sand lightly. ill try remove as little as possible. And then hope the sealant does its job.

    Thanks guys , im happy that i can continue the build.

  7. #7
    apriliaforum prov-nov
    Join Date
    Apr 2016
    Carlsbad, CA, USA

    I had luck with JB weld on some cases, Honda NSR250. They were not in as bad shape as yours. I sanded the area, then put JB weld on a few places, sheared it flat, and then lapped the cases on an ultra flat granite surface. If you don't have a $25,000 air table surface at your disposal, you could use glass/window.
    2007 RXV 450, 1996 Ducati 900SS, 1994 Honda NSR MC28SP, 1993 Honda NSR MC21R, 2002 Yamaha WR426

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