So, I got my hands on this Yamaha XS400 a while back. Wasn’t really searching for this specific model, you know? Just kind of happened upon it. It was sitting in someone’s shed for ages, looked pretty beat up. Think it’s an ’81, maybe the Special II version? Anyway, the guy basically gave it away. Heard these things aren’t worth a fortune unless they’re mint, and this one was definitely not mint. More like… neglected.
First thing I did was haul it back to my place. Just let it sit there for a day while I walked around it. Looked rough. Real rough. Covered in grime, tires totally flat, seat had a tear. Made a quick mental checklist.
The Teardown Begins
Needed a serious washdown just to see what I was dealing with. That took forever. Lots of degreaser and scrubbing. Found some surface rust, but the frame seemed solid enough, thankfully. Started taking things off: seat, tank, side panels. Just wanted to get a good look at the engine and wiring.
Checked the engine first. Was worried it might be seized up after sitting so long. Popped off the little side cover, put a wrench on the crank nut. Gave it a turn… and it moved! Phew. Big relief right there. Drained the old oil, looked like sludge. Nasty.
Tackling Fuel and Spark
Knew the carbs would be a mess. Pulled those off next. Yep, gummed up bad inside. Took them completely apart on the workbench. Jets were clogged solid. Sprayed everything down with carb cleaner, soaked the metal parts. Used a thin wire to poke out all the passages. Felt like I needed tiny surgeon hands. Found a rebuild kit online, ordered that up with new gaskets and o-rings.
While I waited for parts, I looked at the spark situation. Pulled the old plugs out, they looked terrible. Put new ones in. Rigged up a temporary battery. Turned the key… got nothing at first. Found a few crusty wire connectors, cleaned those up. Tried again. Got spark! Not super strong, but it was there. Progress.
Then the gas tank. Smelled awful. Poured out the nasty old fuel. It looked rusty inside too. Dumped a bunch of nuts and bolts in there with some cleaner, capped it, and just shook the hell out of it for like twenty minutes. Rinse, repeat. Got a lot of crud out. Still not perfect, but way better. Threw on a new fuel line and a cheap inline filter just in case.
Putting It Back Together
Carb kit finally showed up. Carefully put the carbs back together with the new bits. Slid them back onto the engine boots. Hooked up the cables and the new fuel line. Put the tank back on, added a splash of fresh gas. Topped off the oil. Okay, deep breath.
Turned the key, lights came on. Hit the starter button. It turned over… and over… gave it a little twist of the throttle… coughed once… kept cranking… then VAROOM! It fired up! Ran like crap, smoked a bit, but it was running! Man, that sound was good. Let it warm up, played with the idle screw. It died a few times, started it back up. Finally got it to sort of idle, though it was shaky.
Still A Ways To Go
So yeah, it runs now. Which is huge. But still lots to do. Needs:
- Proper carb sync
- Brakes need a full check and bleed
- New tires, definitely
- Chain and sprockets look pretty worn
- General tidy up of wires and stuff
It’s a project, you know? Chipping away at it bit by bit. Not trying to make it perfect or anything. Just want to get it safe and reliable enough to cruise around on. It’s kind of fun, taking this old forgotten bike and getting it working again. Slow work, but satisfying when things actually start working right.
