MJK's '78 Brat


XS400 Member
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Chicago, IL
I am attacking this differently than most build threads. We already finished the bike, but just want to give back to the community if we can after learning so much from this forum in the process, from tips and expertise to inspiration.

My cousin and I are both 20 and in college, and he texted me one day before finals week asking if I wanted to build a motorcycle this summer. I said yes, and contacted every Craigslist seller in Chicagoland and northwest Indiana with a promising bike under $800 or so dollars. After some soul and craigslist searching, we bought a near mint '78 XS400 E with 6500 miles for $650 dollars. It didn't run and had some light tank dents along with a frozen front brake, but the owner said it was just the points that needing adjusting and the brake was fine. Taking his word for it, after maybe 2 weeks of even considering owning a bike, we dove head in, and after a 3.5 hour harrowing trailer ride down the Indiana toll road, we got the bike home and started later that night.

We always liked cafe racers, but some components were out of our price range. We thought going simpler would be easier and cheaper, as we wanted to keep the build cheap for my wallet (his parents won't let him ride, so I get the bike, but we both wanted to work on it). Brat style and stripped down industrial became our target.

Getting down to what we actually did:
We started by stripping all of the old fenders, lights, seat, etc; a fairly straightforward process. The frame was chopped with an angle grinder to the rear suspension mounts right away. The paint on the tank was quickly peeled off with aircraft remover, and the metal sanded with 1000 grit wet then treated with RPM magic rust preventer. The stock air boxes were replaced with pods from eBay, gaiters were added, and the battery was replaced with a smaller, 3ah AGM motorcycle (moped?) battery less than 1/2 the size of the original tucked under the seat with metal strapping. The carbs obviously came off and were cleaned twice before running perfectly, while a new float was installed in one of them and float gaskets in both. The throttle cable had to be replaced as it had been used to within an inch of its life, while the clutch line had to be rerouted slightly to pick up slack from changing handle bars.

The custom seat pan was made out of 1/2" birch plywood as we're pretty good at woodworking, and covered with two layers of 10mm thick excercise mat and 2 layers of 3mm thick yoga mat, all glued together with 3M super 77 adhesive. The covering is simply vinyl from jo ann fabrics that cost $20 a yard ish and was stretched and carefully stapled to the wood underneath the seat. Bonus: because the seat pan is wood, it was easy to sand to shape, and mounting the electronics just took wood screws and no patience at all.

Handlebars were obviously replaced with superbike 2" rise ones, and slash cut shorty mufflers replaced the original set. New HEL brake hoses were installed front and rear after thorough system cleanings (tons of muck and bleeding issues), and these hoses now accompany the updated control levers. That being said, I cannot say enough positive things about how quality these new hoses feel and fit. Bolts throughout were replaced with stainless steel or zinc as needed.

Electronically, an LED turn signal taillight unit was installed out back, and two small strips up front, which required rewiring the dash light with a diode bridge along with an LED enabled flashed. A new sturdier "blade" style fuse box with replaced the old glass tube one. Finally, two license plate bolt lights were installed on the new mount off of the lower left shock mount.

Overall, this was a great learning experience, and I think we created a pretty badass looking bike. It runs well and gets after it both accelerating and braking after all of our cleanings and updates For the $1300 we spent all in, I think this could not have turned out better and created some great memories and frustration along the way.

I hope someone gets some inspiration or ideas out of this, and feel free to ask questions, as lots of you helped me to build this directly or indirectly and I'd like to give back as I already said.

Additionally, I now have tons of spare cosmetic OEM parts in used but good condition, just shoot me an offer+shipping if you think you might be interested. There won't be price gouging, just looking to recoup a little bit.


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