Alright, let’s talk about this Honda CBX motor I’ve been messing with lately. It wasn’t exactly planned, just sort of happened. Found this lump sitting in the corner of a buddy’s shed, gathering dust for who knows how long. He was clearing stuff out, asked if I wanted it. How could I say no to a CBX six-cylinder, right? Even if it looked pretty rough.
Getting Started – The Teardown
First thing was just getting it onto my workbench. Thing’s heavier than it looks. Didn’t even try to turn it over initially, just wanted to see what horrors awaited inside. Pulled the valve cover off first – honestly, not as bad as I expected under there. Some old oil sludge, but the cams looked okay, no major scoring or anything obviously broken.
Then came the fun part. Those six carburetors. Man, what a setup. Getting them off as a single bank was a bit of a wrestle. Lots of old, cracked rubber boots and stubborn hose clamps. Laid them out carefully, knew they’d need a full strip-down and clean later. That’s always a job you need patience for.
Basic Checks and Cleaning
With the carbs off, I could get a better look around. Decided to do the simple stuff first, get a baseline.
- Drained the oil. Yeah, it was nasty. Thick, black stuff. Glad I didn’t try starting it like that. Let it drip out for ages while I poked around elsewhere.
- Pulled the plugs. They were pretty fouled, as you’d expect. Gave me a chance to peek inside the cylinders a bit with a flashlight. Looked reasonably okay, no obvious piston damage.
- Checked the air filter situation. The original airbox was long gone, just had these crusty pod filters on the carb inlets. Tossed those immediately, they were falling apart. Need to figure out a better solution there.
The Real Work Begins
Got some fresh, cheap oil and a new filter, filled it up just to help flush things out later. Then I put a wrench on the crank nut and tried turning it over by hand. Relief! It turned smoothly. No horrible grinding noises, no tight spots. That was a big win.
Next up, tackling those carbs. Took them completely apart, one by one. Soaked everything in cleaner, blew out all the tiny passages with compressed air. Jets were clogged solid on a couple of them. Replaced all the o-rings and gaskets – you just have to with carbs this old. Putting them back together and trying to sync them up on the bench as best I could… well, that took an afternoon by itself. Patience, lots of patience.
Also spent a good while just cleaning the outside of the engine. Years of grime and grease build-up. Used a ton of degreaser and elbow grease. Makes working on it much nicer, and you spot things you might miss otherwise, like weeping gaskets or cracks.
Getting it Running (Sort Of)
Finally got the carbs bolted back on with some new intake boots. Rigged up a temporary fuel bottle, checked for spark (which was surprisingly okay), held my breath, and hit the starter button on a test rig. After a bit of sputtering and coaxing… it fired! Ran rough as hell, obviously, but it ran. All six cylinders seemed to be contributing, which was amazing.
It smoked a bit, probably from oil sitting in the cylinders and exhaust, but the sound of that inline-six, even rough, is something special. Let it run for a short bit, didn’t want to push it without proper cooling hooked up. Shut it down, feeling pretty good.
Still a long way to go. Needs a proper air filter setup, carbs need balancing properly on the bike, probably needs valve clearances checked, full tune-up. But it’s alive. Taking a motor that’s been sitting dead for years and hearing it run again, that’s the payoff right there. Now I just need to find a frame worthy of putting it back into.
