81 XS400H – putting the Trusty back into Rusty

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.
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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.
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.
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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.
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Finally I bench synch'ed the throttles using a bit of fishing line.
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That's it with the carbs. After I get these back on the bike, I think the fuel tank is next for some attention.
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.
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.
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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.
The final top coat of paint is on the tank and side covers.

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.
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.
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It is now time to move on to cleaning up the hubs.
Put on some Barry White and focused all of my attention on the rear end:
Rear end together.JPG

Everything is now done back there except for the rear wheel related items.

Also pulled the exhaust out to put it through the rust remover. Liquid rust remover is like a pet goldfish - it is fun while it is active, but at some point you know you will have to flush it down the drain. That point is nearly here with my last bit of magic elixir. The MAC muffler is also now apart.
MAC muffler internals.JPG

Not a complicated baffle, just two pipes overlapped. As you can see, part of the front section is rotted away, so I will have to repair that before it goes back together again.

I still haven't gotten to the wheel polishing yet, but I did get my new spoke and installed it.
The exhaust rehab is now done. First a small sheet metal patch got fitted up to repair the rot in the muffler baffle.
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That got welded up as well as some pin holes in the header pipe.
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A new coat of paint finished everything off.
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I have no excuse now - the wheels are definitely next.
Hallelujah the wheels are done!

These took the prize as the rustiest, crustiest pieces of crap on the whole bike, and I really did not look forward to working on them. Now that they are done, my attitude has improved quite a bit. Good thing because my beer (and sandpaper) budget took quite a hit in the last week or two.

These wheels got every trick I know thrown at them and every maintenance part has been replaced.
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The brakes are brand new as well and the front shoes have been synchronized on the bench.
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All I need now is a front end so that I can get the things mounted.
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That is what’s forking next.
A new bar, the controls and the front-end electrics are now back together.
Controls installed.JPG

The stock cables for the brake and clutch are about 5 inches too long for the bar I am using. I have some new ones on the way that I hope to have by next weekend. Trusty Rusty also has its exhaust hung and ready to go.
Exhaust mounted.JPG

I am going to get the battery back in and test the electrics now that everything is on the bike. The big test will be seeing if the TCI fires both plugs. Fingers are crossed.
@Dean grigson - Thanks. I don't think of this as a restoration as there are a lot of mis-matched stuff on this bike and I am going to do some slight mods to it as well. But, while I was in there I figured I might as well take care of what bugged me (like the rust.)

I would encourage you to make your bike what you want. If it runs, fix it up as you go. If it is a dead cast-off like mine was, take your time, be methodical and enjoy the project as your finances let you do it.

You know where to come if you have questions!
Finished the first round of tuning on the bike. Checked the float bowl levels on the bike, set the idle mix screws, set the idle, checked the timing and then balanced the carbs.
Carb synching.JPG

Then, I did that all over again. Afterwards the plugs looked pretty good, with a nice, cinnamon/brown color on the insulators (the picture looks a lot darker.)
Plug color.JPG

Now that I have a few good hot/cold cycles on the engine, I am going to check/adjust the valve lash and repeat the process above until I don't have to adjust anything.
The second round of idle carb tuning is done. The bike is running very smoothly with instant response at throttle roll-on and no hanging at roll-off. The plug color is looking very good on both cylinders as well.
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I have made an adjustment to richen the left idle mixture screw a bit (based on plug color) and we will see how that does when I run it again, but the basic idle speed adjustments are very close to being done, except that I keep changing one important thing that effects fuel mixture - I have been playing around with some muffler wrap in the silencer. Before first start I really wrapped the baffle with several layers of fiberglass.
Muffler packing1.JPG

The resulting back pressure was way too much however. Before my second tuning session, I took most of the layers off and left just one layer of fiberglass on the baffle. My calibrated “hand over the tail pipe” told me that things were better and that is what I re-tuned the carbs for. However, I am going to try one more thing and only wrap the outlet half of the baffle to see what that is like before I settle on the final configuration.
Muffler packing2.JPG

I have never played around with baffle packing before, so this is interesting to me. The muffler makes this sort of testing easy to do, so I figure now is a great time to mess around with it and learn something new.
Wet sanding of the tank and side cover paint is done. I need to get some pads for my DA so that I can finish polishing these.
Wet Sanding Paint.JPG

The really big task now is doing something with the seat. Besides the buck horn bars and rear wheel, Yamaha did some subtle things with the tank badging and seat to make the bike take on the styling of a cruiser. My goal is to un-pimp enough of what Yamaha did to get Trusty Rusty back to more of what it really is - a standard motorcycle. But I am not a fan of plank seats or loaf of bread seats that a lot of the original standards had, so I am going to work with the stepped seat pan and make this something that might have been seen on a 90's standard bike. This is going to be the one big modification that I am making to an otherwise stock bike.

First, I projected a line from the bottom of the tank to the skirts of the seat pan with a wooden batten to get a smooth transition line.
Seat pan trim.JPG

That got trimmed off and a new foam seat blank has now been glued together.
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Next I need to start shaping the foam into something nice to sit on and to look at. I will soon find out if I was really paying attention in that art class I took in 8th grade.
Happy New Year! I haven't had much going on since before the Thanksgiving holiday through until now, but now that all of that is in the rear view, it is time to get on with a few things. First off, I have started polishing the tank and side cover paint work and noticed a crack in the left-hand side cover.
Side Cover Crack.JPG

It is either something I didn't notice prior to painting or it happened just as I was installing it. Either way, I need to fix the side cover and I will probably document what I do here for anyone else with the same issue.

I also noticed that my side stand was bent and the shoe extremely worn on one corner, so I have taken the opportunity to hammer the thing straight again and fix the shoe plate with a little welding and grinding. The fit on the frame tang was a bit sloppy, so I also put in a brass shim to tighten the fit up a bit.
Side Stand2.JPG

I do like doing the welding and grinding in the winter as I already have a jacket/long sleeves on as PPE on for letting some spark fly.

I haven't really done anything more with the seat other than to fabricate up a foam shaping tool that I will be trying out. More on that later.