My XS400SG Project


XS400 Addict
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OFallon, MO
Hello everyone. I was pleasantly surprised to come across a forum for the XS400. I have been working on a 1980 XS400SG and thought I would start a build thread. Here are a couple of photos of the beast as I brought it home.

Many things wrong with this little guy.

Pulled the motor for easier cleaning.

Got the carbs apart for a good cleaning.

I'll post more progress pictures. Today, I'm planning on prepping the frame for paint.

The 400 is my second project. Here's a picture of my first. I spent a year re-working this 1982 XJ750 Seca. It's my daily rider.


I'm still kind of deciding how to finish the 400. I'm toying with the idea of converting it into a dual sport to explore the local back roads. But I'm mostly leaning toward basic stock to use for general riding. Everything I read on the 400 says that it's fun to ride.
Man, that is a helluva differance in your Seca!! It looks clean enough to eat off of! If you dont mind us knowing, around how much damage did the restoration do to your wallet? Very nice, I cant wait to see the XS!!
If you dont mind us knowing, around how much damage did the restoration do to your wallet? Very nice, I cant wait to see the XS!!

The bike I started with was in extremely poor shape. Luckily, it had good compression and the transmission was in great shape. Below is a list of repairs and approximate cost of each. The list includes the cost of the bike.

This is a cut and paste from an excel file, so I hope it displays legibly in the post.

Engine Mat'l $
Cost of Bike 400.00
Installed stock air/fuel jets
Installed stock Y-13 needles
Changed carbs to bodies with fine threaded mixture screws 80.00
Replaced missing lower carb bracket with idle adjusting screw
Cleaned/Rebuilt Carbs including throttle shaft seals 110.00
Adjusted valves 25.00
Changed Oil/Filter 5.00
Changed Air Filter 25.00
Installed new (from eBay) stock headers, collector box, mufflers 175.00
Installed new header seals 15.00
Removed cam chain slack
Checked compression
Replaced airbox boots with new Fernco boots 15.00
Installed new valve cover gasket 35.00
Installed new valve cover pressure washers 15.00
Replaced right side engine cover 15.00
Installed inline fuel filter 5.00
New spark plugs 12.00
derusted tank
Installed new Alternator shaft seals 30.00


Installed new front/rear tires 200.00
Installed new tire valve stem cores 5.00
installed new front brake pads 25.00
Installed new rear brake shoes 30.00
rebuilt front master cylinder
rebuilt front brake calipers
installed new front brake hand lever 20.00
Installed new fork seals/dust wipers/cap orings 60.00
Installed new fork oil 10.00
pressurize forks to 10 psi
Checked level of rear differential lube
Replaced missing mirrors 28.00
replaced missing fasteners 15.00


Checked coil/pickup resistances
Checked regulator/rectifier resistances
Installed new alternator brushes 30.00
cleaned all connector contacts
Installed new Fuse holders/fuses 15.00
Installed new blinkers 20.00
Installed new headlight lamp 8.00
Replaced missing start button 4.00
fixed horn wiring
Installed automotive flashing unit 5.00
Installed battery tender lead
Installed new battery 30.00


Painted carb hats
polished alloy covers
Painted tank and body parts
Added gas tank seam trim
cleaned frame
painted front and rear wheels
Painted front brake rotors
Painted frame
Painted center stand
Restored plastic parts Back to Black
Cleaned motor

Total Cost including original bike 1,487.00
Yea, the forks were designed to be pressurized. You can tune the ride by adjusting the air pressure between 5 and 17 psi. These forks also have an anti-dive system. There is a brake line that goes from each front caliper to an assembly at the bottom of both forks. When you brake, the system adjusts the dampers in each fork to keep the front end from diving.
No, not the XS, Hardtail asked me about the restoration and cost of my XJ750. The list I posted was the list of items I did to the XJ. It has the pressurized forks with anti-dive units. Sorry if I was not clear.
Not too much damage in my opinion, especially for how well the bike looks compared to before. Im sure it runs and drives a thousand times better too! Nice work.
No, not the XS, Hardtail asked me about the restoration and cost of my XJ750. The list I posted was the list of items I did to the XJ. It has the pressurized forks with anti-dive units. Sorry if I was not clear.

my bad :doh:
i just read my post and realized three things.

one: i have a typo where i said bike instead of back, but that is not really a typo, more like a conveniently, ironic, mistake.

two: i said adviced instead of advised near the end of my post.

and three: that my post had nothing to do with the post to which i was replying.

i wanted to say thanks for the inspiration cturek, and that i know i cannot compete, but that i want to because, man, them bikes look nice.

i will try and post mine so you guys can get a laugh.
Found an '82 xs 400 at a yard sale down the street and bought it for 240. They were advertising 5, but were not able to get it to start in front of me. Well, the battery was dead, and they tried jumping' it. I am not an 'engine' guy, yet!

I work in an engineering shop on campus, and with help from friends got the sucker to start.

Found out the battery was dead.
then, fixed the wiring, and I am not sure how; only thing I can say for sure, right now, is that there was a ground that was connected to nothing. We ended up checking connections, and finally put everything back together, checked everything. Found out we did not have the fuel on. There is a 'pri', 'on', and 'res' setting. When we discovered that the fuel poured out on 'pri' and hit the start button, she cranked right up and sounded beautiful.

So, we went out and celebrated. I bought my buddy a beer for helping me; since I am pretty much ignorant of electronics too, and he gave me the motivation to keep trying and did most of the work for me.

The next day came and I had no luck. Actually, that night I had no luck, no luck.

Next day, no luck, and I let it go, mostly because it was Sunday!

Monday, a professor who runs the machine shop suggested I use carb. cleaner to try and start her up. I had, excuse me, it had been suggested that I try some ether, or, starting fluid, but I didn't have any, and Monday, with the carb. cleaner, she started up.

I rode it around the parking lot, happy as can be. . .

I have no helmet, it is not registered, and I have not the legal license, yet. So, I let it sit for the afternoon.

That day, she was humming! Idling like a champ, and when the choke was on, just a little bit, she idled at like, I don't know, a thousand. Seemed good!

Well, when I came back to get her out of the shop and take her to the apartment, she started getting squeamish. I couldn't get it to idle very nicely, and I felt like, maybe she was not getting enough gas.

I forgot to mention that there was old gas in the tank before. I finally dumped it out and put new gas in the tank, but, regardless, I rode her home and I am pretty sure I drove it into the driveway on the last leg.

Couldn’t get her to start anymore, and I remain unable to, at the moment. I have been advised to take the carburetor apart. I am probably about to do that. clean it, and replace.

Thanks for reading, if you did, and I look forward to showing the progress and, hopefully, hearing anyone else's thoughts.

I appreciate the thread cturek. I needed some good inspiration to start this project.