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81 XS400H – putting the Trusty back into Rusty

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

  1. JPaganel

    JPaganel XS400 Addict

    Shaft seals are still available new from Yamaha.
     
  2. CaptChrome

    CaptChrome XS400 Addict

    The carbs are going back together. The first order of business was a slight modification. I had ordered new throttle butterfly screws from MikesXS, but they turned out to be a little long. So I first needed to grind them down a bit and hand file a bevel in the tips so that they start easily and don't cross-thread in the shaft.
    Carb reassembly1.JPG

    When installed, those screws were originally staked to prevent them from backing out and getting sucked into the engine, so I did that also with some needle-nose vice grips and a bit of plate. This left a nice score in the screw ends and deformed them so that they won't back out. But, being as I was already in there, I also applied some blue Loctite.
    Carb reassembly3.JPG
    Carb reassembly2.JPG

    Lastly I put all of the other parts back in which was straight-forward.
    Carb reassembly5.JPG

    Jetting is completely stock. I installed a new float valve, seat, and net filter, replaced the bowl gaskets as well as all of the rubber parts inside including the throttle shaft seals. The pilot air screws are three turns out for initial restart. Next up is to set the critical fuel level in the float bowls.
     
  3. CaptChrome

    CaptChrome XS400 Addict

    Carburetor bench tuning:

    I set the float heights with the bowls off to make sure that both sides of the float were the same and then put the bowls on to establish the fuel level. Each carb was leveled, supplied with fuel and the level was measured. The spec for this bike is 3.0mm +/- 1.0mm. It took two rounds with each carb, but both are now set to 3.0mm. The manual has you do this with the carbs on the bike and immediately after running the motor, but it is a lot easier to get it set now and just check the level after they are on a running bike.
    Carb reassembly7.JPG

    The carbs then got ganged back together. Here are the Mikuni sisters back together again. They do look much better after their day at the spa.
    Carb reassembly8.JPG

    Finally I bench synch'ed the throttles using a bit of fishing line.
    Carb reassembly9.JPG

    That's it with the carbs. After I get these back on the bike, I think the fuel tank is next for some attention.
     
    JPaganel likes this.
  4. CaptChrome

    CaptChrome XS400 Addict

    I have a bit of a mixed bag of progress. First, the carburetors are back on the bike as well as the H-pipe and the air boxes. Once again it is nice to remove big chunks of stuff from my part bin and put them someplace where they really belong.
    Carb install2.JPG

    I also got started on the fuel tank paint work by sanding off the old finish and putting on the base coats of primer.
    Tank paint2.JPG
    Next will be the finish primer and topcoat along with some sanding in between all of those steps.

    Finally, I procured a center stand. However, because I was concerned that Trusty Rusty might reject the transplant if it had too good of a pedigree, I got the rustiest stand I could find. Here it is after I knocked the biggest chunks of mud off:
    Center stand.JPG
    I did hold the stand up to the mounting tabs on the bike and Trusty Rusty seemed okay with it, so I believe this will work out just fine.
     
  5. CaptChrome

    CaptChrome XS400 Addict

    The inside of my shed is hotter than a two-dicked dog. Not much is getting done and temperature is out of range to mix and apply paint. But I did get the finish primer on right before the heat wave. And, early this morning before conditions got too hot, I sanded for the application of the top coats. I make up a guide coat to apply when I sand, and I learned something this time.

    Some folks use enamel spray paint for the guide coat, but I don’t like to put a one part paint over my two part paint. So, to make a guide coat I add some water-based ink to denatured alcohol and then dab that onto the surface that will be sanded. You sand until you don’t see the color anymore, or you add some fairing compound to fill any really deep spots that just can’t be sanded flat. Any ink that remains on the surface after sanding gets washed off when I clean the surface of dust and solvent wipe it before the next coat. I have used old inkjet printer ink to make the guide coat in the past, but this time I grabbed some food coloring from the kitchen, added that to a little less than a cup of denatured alcohol and applied it.
    Guide coat1.JPG

    The issue I ran into is that I didn't think things through and picked blue as the color to use, and since the base primer was gray and the finish primer whiteish, it was very hard to tell when I had all of the ink removed as the underlying colors kind of had a blue hue.
    Guide coat2.JPG

    I carefully got the job done, but there is always something new to learn with this project. I probably should have used red or green coloring.
     
  6. CaptChrome

    CaptChrome XS400 Addict

    The final top coat of paint is on the tank and side covers.
    Topcoat1.JPG

    I plan on wet sanding and polishing these once fully cured as I rolled the finish primer and topcoat on. The paint leveled nicely, but some spots could use attention and there is no better time than now.

    The wheels are next on the work list and the biggest issue with them is very rusty spokes. I knocked together a crude "tank" to suspend the wheels in to soak in the rust remover. It is big enough that I can also do the fenders in it as well while still conserving the volume of rust remover I need to add.
    Wheel tank.JPG

    Yes I know it won't hold liquid - I plan on lining it with a heavy gauge plastic bag.
     
  7. CaptChrome

    CaptChrome XS400 Addict

    Lately I have been removing more rust.
    Wheel rust bath.JPG

    The wheels and fenders are now done and some odds and ends along with the center stand are now in the rust bath. The wheels came out in fairly good shape. I have checked true and run-out on both and no adjustments will be needed. I do have a broken spoke on the rear wheel, and a replacement is being made by Buchanan’s Spoke and Rim.

    The front fender had a bit of a twist and a crease, so I did my best at beating that back into shape before giving the bare undersides of the fenders a coat of primer and paint.
    Fender paint2.JPG

    It is now time to move on to cleaning up the hubs.
     

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