Whatever: Carburetor Angst

John Burns
by John Burns

More of life's mysteries revealed

I wondered out loud the other day, during a MO conference call, how many new motorcycles still have carburetors? Not much more than a day later, Dennis Chung shared an Excel spreadsheet with all of them. It’s about what you’d expect: Three Rokon Rangers, Suzuki and Yamaha DS and TW200s, Honda’s XR650L soldiers on alongside Suzuki’s DR-Z400s and DR-650s… the Honda Ruckus still has a carburetor. Beyond that, there are a bunch of Kymco and lesser-known small-displacement scooters you’ve never heard of. I have never had the pleasure of seeing, much less riding, Taizhou Handa Engine Science Co., Ltd.’s Adonis, Defender, Discovery, Excursion, Falcon, Falcon R, Super, Super R, Vestalian, or Wasp.

I’m not going to miss the carburetor in any kind of practical way, but I’m totally going to miss it in a romantical one, like people used to pine for liver and onions and mustard plasters and things. I messed with carburetors on a few cars before I found motorcycles, but most of them I just read about in magazines. Some had really cool names that just sounded fast: the Rochester Quadrajet. The Carter Thermoquad sounds like nuclear war. The Holley double-pumper (!) came in sizes up to 850 cubic feet per minute of air, and after that was the Dominator, for use exclusively on God knows what? Top fuel dragsters and NASCARs. Two of them mounted sideways on top of your blower! Foreign cars had Zenith Strombergs and Weber side-drafts and things, which looked like little musical instruments, a mini Tijuana Brass horn section hanging off the side of your engine. Fuel injectors come in 10-hole and 12-hole, far as I can tell. Not nearly as interesting.

Herb Alpert. Not really. Giotto Bizzarrini, Ferruccio Lamborghini and Gian Paolo Dallara at Sant’Agata Bolognese in 1963, with a Lamborghini V12 engine prototype. (Wikipedia photo)

On motorcycles, if you were super-cool and bucks-up, you could replace your bike’s stock carburetors with Keihin FCR flatslides, or Lectrons like Kenny Roberts, or Mikuni radial flatslides. Adding “radial” to anything makes it instantly cooler. On one of the later iterations, the slides rolled up and down on little wheels to reduce stiction, because you sometimes heard horror stories about guys whose throttles got stuck WFO! (Wide Fuggin’ Open!).

Probably what it is is simple backlash against the digital age. All carburetors are inscrutable in different ways, but you can eventually get to the mechanical bottom of all of them, in a way that will never happen for me and my iPhone. I forget exactly what springs and things I played with in the 650 Holley atop my 396 Chevy, but when you got all the stars aligned and kicked in the back two venturis (out of four), you were going places, buddy – if you had the dual points adjusted right in your Mallory distributor, that is.

Gaping maw. The two little nozzles under the Phillips screws squirt gas like Gushers candy when you stomp on the gas, and you can change their size and duration of squirt. Double pumper.

It was fun because you had to be involved, and could feel the results of your expertise even if it was as rudimentary as mine. (Later, when you became an adult and had other things to attend to, it was probably just a drag. You’d have to drop your car off at the garage for a tune-up. On cold mornings, you could hear up and down the street whose cars had not been tuned up lately, as they cranked slower and slower, before failing to start. Then again, most adults just bought a new car every few years, since the body had mostly rusted away by then anyway.)

The same was true of motorcycles only moreso: With a good jet kit and a new exhaust pipe, you could transform your stock FZ or GS or whatever into a thing that sounded way faster even if it wasn’t. Usually it was, if you’d bothered to read the directions that came with the jet kit – all for maybe 5 or 600 bucks. The magazines spent many pages explaining just how to go about it, including how to slip little washers under the jet needles (or was that the needle jets?) to get rid of that annoying little off-idle flat spot, for people like me who were too poor to afford the $69 for the jet kit.

Everybody was a climate denier then, when we weren’t busy being sexual predators, which reminds me of the newfangled Predator carburetor! In those days following hard upon the Sexual Revolution, to me it seemed like the sexes took turns being prey and predator. Some of the girls I knew packed a meaner punch than most of us boys. (Much like my carburetor knowledge, I got most of this from reading and hearsay more than doing.)

I didn’t mean to get into a carburetor/opposite sex comparison, but there is a certain mystery the two things have in common. If you could discover the secrets, how to manipulate the spray nozzles and springs just right, say the right things – you were setting yourself up for happiness and burnt rubber. Stop me if I told you about the time I visited Rob Muzzy’s shop in, I think, Hesperia, California. He had one of the first dynos around, and I had brought a new Kawasaki ZX-7R there for a run – (the racey one that came with 39mm Keihin flatslides, fed by a ram-air system using vacuum cleaner hoses routed through the gas tank).

Be still my beating heart… so peaky, so uncomfortable, such a PITA on the street. I loved her.

While I was hanging around in his shop waiting for him to get off the phone, I spied something on Muzzy’s immaculate workbench, under a neatly folded shop towel. I had to look. Oh, a bank of carburetors… while I was fondling them with my eyes, Muzzy came into the room, furious. What the hell are you looking at?! DON’T YOU KNOW NEVER TO LOOK AT A MAN’S CARBURETORS??

Gee, Mr. Muzzy, I…


If I’d been looking right at the top-secret key that made Muzzy Kawasakis so fast, it went right over my head. But I totally felt like I’d been caught in the act lusting after Mrs. Muzzy or something. A serious violation. To this day if I’m really angry, I’ll have the urge to shout, don’t you know better than to look at a man’s carburetors?

More artifacts from MotoGP Werks. (That’s its carburetor candy case in the lead photo, too.)

I’m actually feeling pretty smug as I write this, because even though I didn’t start it for a few months, my old 2000 R1 fired right up a few days ago, on all four cylinders. I could visualize the fuel being sucked up through the tiny holes in its four shiny pilot jets as each cylinder ignited; God knows I’ve cleaned them out enough times. (I finally figured out it’s worth it to just bite the bullet and put race fuel in the tank if it’s going to be sitting for a while.) The 2000 was the last year of carburetors on that bike. It’s an antique.

The other bikes currently on loan in my garage, a Z H2 and a Honda ADV150 scooter, can be completely counted on to start up instantly and run perfectly. But when I spin their starters, I… I just can’t visualize what’s going on inside those fuel injectors? Similar to what’s going on in my iPhone I suppose. Fuel injection makes me kind of angry: all the gas fumes I inhaled over the years, all the hours I could’ve spent learning the cello or something – I coulda been Yoyo Ma if electronic fuel injection had gotten here sooner. Like learning long division and how to find square roots before the calculator. Do they even make kids learn that stuff anymore? The things a boy could’ve been doing with his youth. Oh, what’s the use. Say, don’t you know better than to LOOK AT A MAN’S CARBURETORS?!

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John Burns
John Burns

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2 of 24 comments
  • Mad4TheCrest Mad4TheCrest on Jan 01, 2021

    I now have two bikes with 'modern' EFI and one from the dim mists of 2001 with carbs. Although the EFI bikes' fueling is overall fine, their throttle feel isn't as smooth and intuitive as the carbed bike. Well, as long as I run chemtool through the tank every now and then. I hadn't thought to use race gas; nice tip. 👍

  • Dan Aisner Dan Aisner on May 13, 2023

    Carburetors, RAM Air, and a UEGO wide-band make a great pairing for the DIY'er looking for tuning gratification. The UEGO doesn't lie or let the tuner think something other that what is happening with their jetting under real-world conditions. A few adjustments and you can end up with something very uniquely tuned to perfection.