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1975 XS650B

Discussion in 'The Garage' started by BCoop, Nov 19, 2014.

  1. BCoop

    BCoop XS650 Addict

    I have some questions about my 1975 XS650B. When I pulled the engine and began to drain the oil I noticed some metal shavings. When I took the oil filter out of the right side cover it also had some metal shavings. Where could this come from?

    I would also like to know a couple things about valves. One of the exhuast valves is bent, but the rest look to be ok.

    Would I be able to replace just the one valve or should I go for all of them?

    Is the guide(or guides) in need of replacement ?

    Do all xs650 years have the same valves or did they change with year and model.

    Could I order replacement valves from a Yamaha dealer?
  2. 5twins

    5twins XS650 Guru Top Contributor

    Yes, you could replace just one valve. The guide would depend on the valve to guide fit. If that's still OK and not sloppy, it doesn't need replacing. You could get the valve from Yamaha or check eBay, lots come up there. You might get a deal but compare prices. Lots of eBay sellers charge more than Yamaha.

    The valve keeper design changed in '73. Your '75 should have the new rounded style but that's something you'll need to check. Both types come up on eBay so be sure you're getting the type you already have or you'll need matching keepers too. Here's the tech bulletin that illustrates the change. It's easy to tell what style you have just by looking at them .....

    http://i1020.photobucket.com/albums.../Tech Bulletins/ValveKeepers1_zps919219e0.jpg

    http://i1020.photobucket.com/albums.../Tech Bulletins/ValveKeepers2_zpsb3a20af7.jpg
  3. BCoop

    BCoop XS650 Addict

    That's a relief I think I will go to yamaha for the new valve.

    Could I media blast the head without taking the guides out?

    Would it be better to dip the engine parts in parts cleaner?
  4. 5twins

    5twins XS650 Guru Top Contributor

    I bead blast my heads and cylinders but outside surfaces only, no internal surfaces. I completely and thoroughly block off any openings. I leave the guides in but I'm not blasting in there. Still, with the valve out, I thread a strip of oiled rag through the guide to keep it clean and corrosion-free while I'm cleaning and porting that area.

    I do clean the heavy gunk off first with solvent before placing the head and/or cylinder in my blasting cabinet. No need to contaminate my blasting media any more than necessary.
  5. BCoop

    BCoop XS650 Addict

    Thank you 5twins! I appreciate how quickly you have responded with such great info.
    When you say bead blasting does this mean glass?

    On another note; would heavy metal shaving in my oil filter be a broken down sump or a loose came chain chattering against the bottom case where it meets the jugs?
  6. Pat D

    Pat D XS650 Addict

    FWIW, I soda blasted my head, valve cover and cylinders. I did mask off any finished machined surfaces, but I don't know if this is absolutely necessary when using soda at 100 psi with a happy homeowner compressor and gun. The cool thing is with soda, any media trapped in the parts will dissolve if rinsed with water. I left the guides in place.
  7. The metal shavings can be from a few things. If there seems to be any black plastic mixed in, it is probably the front cam chain guide, which commonly wears out and needs to be replaced. I've also had the gears driven by the starter motor grind and leave metal in the oil.
  8. 5twins

    5twins XS650 Guru Top Contributor

    Yes, I use glass beads. With them, it's critical to not blast internal areas. Some of the beads will embed themselves into the alloy and no amount of washing is going to get them all out. What does release them is engine heat, when the parts expand, and then you will have problems if you've done internal areas.

    As mentioned, soda is less of a problem because it dissolves away with water. Still, I don't see the need for basting internal areas, they're usually not that dirty. Normal solvent cleaning should be enough for them.

    Soda does do a nice job of removing carbon, like on the combustion chamber and piston tops, but they can also be cleaned very well using paint stripper.

    The front guide is aluminum so usually doesn't produce chips but rather ground up aluminum powder. It will give your old oil a sparkling or metal flake appearance. These motors are a rather old and crude design. I think generating a few metal chips during operation is kinda normal. It will probably take tens of thousands of miles before all the parts are fully and properly mated, and the chip accumulation tapers off. I have about 30K on mine now and the filters just recently started coming out relatively clean. You also want to take into account that many of the chips you're finding are probably past accumulations not flushed out because past owners didn't do frequent enough oil changes.

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