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Yam_Tech314's official build thread

Discussion in 'The Garage' started by G_YamTech_314, Nov 28, 2018.

  1. SomervilleXS650

    SomervilleXS650 XS650 Addict XS650.com Supporter

    There was a recent thread on this (https://www.xs650.com/threads/valve-spring-compressor-recommendations.58574/). I posted a link to one on Amazon for $17.

    To me...this is one of those things where the $17 for the tool is well worth the frustration of trying to do the job without it, or trying to make a DIY version. It's not exactly an heirloom tool, but for $17 I have no complaints. If you're careful it should hold up just fine, and you've got the piece of mind of owning the tool if you need to do the job again (as opposed to borrowing/renting one).
    Mailman, Brassneck and Raymond like this.
  2. 5twins

    5twins XS650 Guru Top Contributor

    Yes, the large C-clamp style works best on this motor. There's very little room down around the sides of the springs to get any of the other styles in there.



    Raymond, Mailman and Brassneck like this.
  3. Brassneck

    Brassneck XS650 Guru

    I picked up one of these a while back. It's a bit more expensive, but for the amount of valve work I do on my bikes, it's been a game changer. Having a handle that closes/locks in (think vice-grip style) takes away the fiddly-ness of turning the the bolt to compress the springs. You simply find the right depth, line up the tool, then close the handle and it's done.

    GLJ, SomervilleXS650 and Jim like this.
  4. Mailman

    Mailman Hardly a Guru Top Contributor

    I love how organized you are. I’ll bet nobody else has a rotisserie for working on heads! :D
  5. 5twins

    5twins XS650 Guru Top Contributor

    I love making stuff with my little welder and this is just another example of that. I've done enough head work on these (porting, valve jobs) that propping the head up with blocks of wood was getting old. With this thing, I can set the head at any angle I need, and it was designed so I can flip the stand over on any of it's 6 sides. The rectangular tubing I used came from an old exercise machine I picked up on trash day, lol. It isn't very thick or heavy, but was just thick enough for me to weld (low amp setting, 1/16" rods). Once the head mounting plate is bolted in, it's quite stout.
  6. Visited an old friend and borrows his valve spring compressor. Got my springs and valve back in and all put together properly.

    I filled the chambers with fuel and it does leak a little... Idk if it's enough to really worry about, but I'd like to figure that out.

    Even more concerning however, is the fact that when I put my mouth against the exhaust ports and blow air, it expels fuel from HERE

    20201121_200539.jpg im depicting the fluid rising up from between the steel and aluminum. Perhaps it's because they can't get this process perfect so there's always a small gap that almost doesn't exist at operating temp, and maybe a head gasket deletes this from being am issue... I thought it was interesting...

    I should add that it only leaked about a 16th of an inch of fuel in the course of about 5 minutes. I don't know if that's enough to really matter considering how fast they're gonna be opening and closing.

    Boy, they look good though.
    Raymond likes this.
  7. I also just found another concerning spot.

    This "crack" for lack of a better word let's air pass from the port to above my intake valve... Wouldn't this cause a severe lack of compression? 20201121_201644.jpg

    I think at this point I'm gonna re-lap the valves, and try to get a better seal. And possibly try and address whatever that casting flaw is...
  8. GLJ

    GLJ Never go faster than your guardian angle can fly. Top Contributor

    If that "crack" is leaking back into the intake runner IMHO you will need a different head.
    Hopefully others will give their thoughts.
    Jim likes this.
  9. This was my fear. If I blow air through the port it bubbles right out of that crack.

    I'm guessing there's no way to tig weld and file it.?
    Jim likes this.
  10. GLJ

    GLJ Never go faster than your guardian angle can fly. Top Contributor

    I'm sure it could be fixed. Most likely would not be cost effective.
    Others may have a different point of view.
    Jim and G_YamTech_314 like this.
  11. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Tigging it closed has it's own problems. It's awful close to the aluminum... which would start melting from the heat if not properly cooled... which would be nigh impossible. The heat would also most likely distort the valve seat, requiring it be re-cut. Add to that the other leak and I'd agree with Greg.... another head is your best and cheapest solution.
    GLJ likes this.
  12. Brassneck

    Brassneck XS650 Guru

    That's unfortunate...not sure I understand how/why there would be a gap there? There's a thread on here that discusses this same groove issue on other's heads, but they don't look to be as noticeable or cause any issue...and seem to be factory made. http://www.xs650.com/threads/grooves-on-head.39230/

    I can't recall from way back when you first started the tear down...but were you experiencing compression loss initially?
    G_YamTech_314 likes this.
  13. What a disappointment...

    Can anyone point me in the direction of a SOLID matched pair of head and cover? This is gonna be a larger set back than I really anticipated but I need to just grin and bear this loss, and move on...
  14. GLJ

    GLJ Never go faster than your guardian angle can fly. Top Contributor

    If you do get a used head make sure it comes with the cam cover. I'm a believer that is the best way to go. The head and cover were machined as a set. To be fair people have swapped covers and not had problems.
    I would bet The Baron of Baraboo or another member may have a head.
    G_YamTech_314 likes this.
  15. Unfortunately I never did a compression check. My thought is that the carbon build up helped seal that gap and made it run a little better... It leaked at the head gasket on one of the sides... I'm gonna look back through my thread and see which side it was. I'd put money on it being that side though... I'm pretty pissed. Not gonna lie... But what am I gonna do?

    I'll most likely document an attempt to fix it and see how it goes. Perhaps I can invest in another test motor in the future and see if the attempted fix works? Idk. Seems like a waste to throw it in the scrap bin just because there's a challenging fix. I'll buy a new set regardless, but I feel it may be worth trying to fix.
    Greyandridin and Brassneck like this.
  16. GLJ

    GLJ Never go faster than your guardian angle can fly. Top Contributor

    Put a wanted add in the classified.
    Greyandridin and G_YamTech_314 like this.
  17. Still reflecting on this discovery...

    I'm happy to have found it before rebuilding, but still extremely disappointed that it's no longer gonna be a full out original motor with matching #'s from factory.

    It seems no one is incredibly familiar with this "defect" so it's like buying a 40 year old lemon.

    I assume it's not something I'll have to worry about when buying a used pair of cyl. Head and cover..? I'm still trying to figure out what may have caused this... Could it have been something I did when trying to clean it? The most it went through was a blasting, and being boiled thoroughly and pressure washed, then oiled... I find it hard to believe that would cause this, considering the running temps it would see.
    Jim likes this.
  18. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    There's no numbers on the head that ties it to an engine... so you don't actually know if it's original in the first place. C'est la vie. Find another head and press. :)
    Fwiw... prolly nothing you did caused it.
    Raymond and G_YamTech_314 like this.
  19. Fair enough.

    I'm just trying to learn from it... Do we think it's likely an effect of aging? Perhaps it was overheated at one point in it's life? Could it be like that from factory?

    When things like this happen, I feel they're am opportunity to learn and grow my diagnostic skills. I'll never know for sure... But heat causes expansion which causes problems. It also had a head gasket failure which is another sign of too much heat. But what causes an air/oil cooled bike to overheat anyways? Lack of oil, and idling at a stand still too long? I know it doesn't seem like a big deal but I'm plagued by it now. I wanna figure it out. lol
    Jim likes this.
  20. Jim

    Jim Beyond the edge is the unknown. Here be Dragons XS650.com Supporter Top Contributor

    Over heating's as good a guess as any. After 40+ yrs... who knows.
    GLJ and G_YamTech_314 like this.

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