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81 XS400H – putting the Trusty back into Rusty

Discussion in 'The Garage' started by CaptChrome, Aug 19, 2021.

  1. CaptChrome

    CaptChrome XS400 Addict

    More cleaning of bike bits! But, I did get the engine tidy enough to formally introduce it to my wrenches. The side case covers are now off as well as the alternator and the clutch assemblies:
    Stripped side cover right.JPG

    Stripped side cover left.JPG

    The clutch components measured out fine, but I will be replacing the friction plates just because I am this far into the engine. I did also find an anomaly - one of the the starter clutch mounting screws was backing out of the flywheel. I am pretty happy that I pulled the flywheel off and caught the issue. Having that bolt back out while the engine was operating would do some serious damage to the starter clutch and alternator.

    Next up (besides more cleaning) is to pull the gear selector bits, check the oil pump and then get the heads off and having a peek inside the top end.
     
  2. Buddha

    Buddha XS400 Addict Top Contributor

    I love peeking:laugh:, inside engines that is.
    Great job CC
     
    Last edited: Mar 1, 2022
  3. CaptChrome

    CaptChrome XS400 Addict

    @Buddha - Me too! Past experience tells me that there is always something very interesting to see once I get that cover off - cam cover that is.
     
  4. CaptChrome

    CaptChrome XS400 Addict

    The top end is stripped off, and I haven't found anything that I didn't expect to see.
    Top end apart.JPG

    I did struggle with getting the cylinder block off. Regardless of the hundreds of taps I applied with the plastic dead blow hammer, it would not move. There are only two areas that you can really use any force with the hammer and wooden drift, so that hampered things as well. I finally had to dance a little heat right around the joint and off she came with just a few taps. Visually things look fine. I did have a partially stuck ring on the right piston, but that was sort of expected. Now I need to clean off the old gaskets and break everything down for some measurements.
     
  5. CaptChrome

    CaptChrome XS400 Addict

    The weather has been warm enough to paint lately, so I started pulling the odds and ends out that have been lined up, waiting for nice weather. I also got the bottom of the engine case as clean as I could:
    Engine ready for paint 2.JPG

    ... and pulled it outside for some refreshment (along with some of its buddies):
    Engine paint 3.JPG
    Engine paint 2.JPG

    I hope to get the frame and swing arm outside and prepped for paint also. The sooner I get those painted, the sooner full curing of the coating will be reached, as the start of reassembly will be determined by the engine and frame being ready. I still have a tremendous amount to do, but getting some of the big parts looking good is encouraging. So far lots of nuts, bolts, washers and other parts have been painted, but there is still a big pile of stuff remaining.
     
  6. CaptChrome

    CaptChrome XS400 Addict

    Well, the weather has been uncooperative for painting lately, but tomorrow may be the day I finally get the frame outside for clear coating. However, in the meantime I have made some progress on the engine. The critical component measurements are mostly done, and it looks like the engine is in pretty good shape, and I will be able to reuse what I have.
    Measurements.JPG

    I gave the cylinders a very light hone - just enough to remove some of the staining and establish some cross-hatching.
    Cylinder hone.JPG

    And when refitting the oil pump, I found a typo in the Haynes manual regarding setting of the primary drive gear to oil pump pinion gear backlash. The Haynes manual specifies setting the backlash to 0.4mm and the factory manual specifies setting it to 0.04mm. I went with the factory spec as 0.4mm would be really sloppy. Anyone who uses the Haynes manual only and has done an oil pump install at some point may want to pull the side cover off and check this.
    Oil Pump Backlash.JPG
     
  7. CaptChrome

    CaptChrome XS400 Addict

    Frame clear coat is done and the engine case paint is also.
    Frame paint 1.JPG
    Engine paint 9.JPG

    So now I need to wait for the paint to cure - 14 days. However, as soon as the engine case is relatively safe to handle, I am going to get reassembly done so that it is ready when the frame is done curing. There is an Easter egg in the engine paint picture for someone to find. Good luck!
     
  8. AmbientMoto

    AmbientMoto XS400 Addict

    Wow this is going to be a fantastic end result.
     
  9. CaptChrome

    CaptChrome XS400 Addict

    @AmbientMoto - Thanks. So far so good, but there is still a lot to do and I am sure I will have plenty of opportunities to mess it if I am not careful. Right now I am just happy that the project is moving along with some regular progress.
     
  10. CaptChrome

    CaptChrome XS400 Addict

    Rockers and the tach drive are back in the cam cover:
    Cam cover reassembly.JPG

    I have lapped the valves, checked the contact area with some prussian blue and assembled the head with new oil seals:
    Head reassembly 1.JPG

    And lastly, I did the go/no-go leak check of the head by filling the chambers with alcohol for about an hour and found no leaks:
    Head leak test.JPG

    The pistons have their rings installed also, so I think I am just about ready to put this 391cc paperweight back together.
     
  11. CaptChrome

    CaptChrome XS400 Addict

    The engine isn't together yet. I was putting on the flywheel/alternator rotor and looked again at the starter clutch bolt that had been loose when I took things apart. It showed signs of metal on metal contact, and when I looked at the engine start sprocket, it showed wear also:
    Starter clutch bolt rub.JPG

    The good news is that there are no signs of this having been a long-term problem as there is no evidence of heat/bluing on either part, but there are two things that I needed to check regarding other damage. First is the crankcase. As the bolt backs out and presses against the sprocket, it can jack the crankshaft to the left and start the crank rubbing in the inside of the case. I measured the crank end play with a dial indicator and have 0.004", which I think is okay (there is no spec listed for this). The other issue to check for is damage to the reduction gear in the starter as the engine start gear will try to pull on the starter chain and rotate the starter shaft. I opened the starter and the gears look fine, but while I was in there, I figured I might as well clean it up and relubricate everything:
    Starter rebuild 2.JPG

    And then test it to make sure I didn't mess anything up.
    Starter test.JPG

    I also replaced the crankcase oil seals on the left side and now truly believe I am at the point of putting the top end back together.

    There are usually reasons why a vehicle gets parked without use, and I believe I found the reason why this bike was parked. The bolt rubbing on the start gear probably made a hellava grinding sound when it happened - enough that the rider would pull over and wonder what is happening to the engine. On restart the sound would still be there, so the bike gets parked until the owner gets enough money to hire a mechanic or time to open things up to see what's wrong. I think that time is now; it just took 20 years to happen. And @Buddha 's guardian bells are starting to look like a pretty good idea!
     
  12. CafeMike

    CafeMike XS400 Member

    Where would you get a 2-1 exhaust kit? I have a 81 xs400 currently stripped down and love the clean look of the 2-1.
     
  13. CaptChrome

    CaptChrome XS400 Addict

    I don't think MAC makes them anymore. Your best bet is to put a "Wanted" post in the classified forum here as folks will probably read that that don't follow this thread. Second will be to look on eBay as bike breakers will part out their bikes there.
     
    CafeMike likes this.
  14. CafeMike

    CafeMike XS400 Member

     
  15. CafeMike

    CafeMike XS400 Member

    Did you notice the quality of the welding when you were painting your frame? I am almost finished stripping /sanding and can't help but notice the horrific welding job on my bike... There are splatters, a few holes, some very bad welds etc.. Did you notice that on yours?
     
  16. Buddha

    Buddha XS400 Addict Top Contributor

    Geez, I did 2 frames and was impressed with the factory welds. That sucks that your welds aren't higher quality. Any chance of repairing them while you're down to bare steel?
     
  17. CaptChrome

    CaptChrome XS400 Addict

    I thought the welds were pretty good also. There were a few spots on the frame where it looks like the factory tacked everything up in a jig before assembly and then cut the frame off afterwards, but nothing I was too concerned with as it is generally hidden. I have see a lot worse work, like everything I have ever welded in my life.
     
  18. CaptChrome

    CaptChrome XS400 Addict

    The pistons are on...
    Cylinder assembly 2.JPG
    ... and stabbed into the cylinders.
    Cylinder assembly 3.JPG

    The head went on right afterwards and the engine rotated over very smoothly. So, I set the timing of the cam and installed the cam cover.
    Cam cover install.JPG

    I set the valve lash and the engine is now ready to be installed in the frame.
    Top end done 2.JPG

    I am going to leave installation of the clutch, starter motor and alternator windings until after the engine is in the frame to make the engine easier to maneuver by myself. The frame paint still needs a bit more time to cure, so I will work on getting the side covers cleaned up a bit to fill the time. However, I am pretty excited because Spa day for the carburetors is right around the corner!
     
    spectra likes this.
  19. AmbientMoto

    AmbientMoto XS400 Addict

    You find a good source for your front brake cable? I'm looking for one as well.
     
  20. CaptChrome

    CaptChrome XS400 Addict

    @AmbientMoto I asked about at my local bike shops and they pointed me to another local shop that makes them up. MotionPro also makes up custom cables that you can order on-line as long as you can specify the length you want. Since I am changing the handlebars, I might need a new clutch cable to fit as well. So, I plan to look into both of these options when I have the bars on and look at how everything fits up.
     

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