My taste in vehicles is a little strange. When it comes to bikes, I dig the latest and the greatest. However, when it comes to cars, give me the old stuff. In fact, besides my beater pick-up truck I use to haul bikes around, and my wife’s cushy sedan, my four-wheel collection consists of not one, but two, Datsun 510s. Both with only two doors. Both built in 1971. And both not currently running. Sigh.

What does this have to do with motorcycles? Well, the thing with old cars (and bikes) is sometimes you have to get crafty and creative to keep them on the road. Parts are becoming increasingly difficult to come by, and when you do find that special something, it can often be crazy expensive.

The engine bay of my personal Datsun 510. Pardon the dirt and grime, I know she’s a mess under the hood. Anyway, those sidedraft Mikuni carbs? They were pretty trick...30 years ago.

The engine bay of my personal Datsun 510. Pardon the dirt and grime, I know she’s a mess under the hood. Anyway, those sidedraft Mikuni carbs? They were pretty trick… 30 years ago.

Every now and again, I like to take a peek at the forums to see if any new or innovative ideas have taken hold in the 510 world. Usually the questions I see are simply variations on the standard questions answered a million times in the F.A.Q. section (and no, you can’t get 400 hp from a 1600cc SOHC production engine built in the 1970s, spend under $2000 and drive it to Maine and back. Stop asking.)

However, this particular time my browsing brought me to an interesting topic.The Datsun 510, like many cars from the era, is carbureted. Mine currently sports a pair of sidedraft Mikuni carbs, and though the company is still alive and well, carb development in the automotive sector died in the 1980s. Meanwhile, motorcycles (and snowmobiles, ATVs, etc.) miraculously hung on to carburetors into the new millenium, with the help of companies like Mikuni advancing the technology along the way. Best of all, now that EFI is firmly rooted in the bike world, used carbs are plentiful and cheap. Are you seeing what I’m getting at here?

Leave it to those looking for a bargain to transplant a motorcycle carburetor onto their classic car. In the UK, a small family-owned shop called Bogg Brothers have become gurus in the practice. They prefer the Yamaha R1 carb due to its reliability, smooth fueling, and the provision of a throttle position sensor as standard. Photo: Bogg Brothers

Leave it to those looking for a bargain to transplant a motorcycle carburetor onto their classic car. In the UK, a small family-owned shop called Bogg Brothers have become gurus in the practice. They prefer the Yamaha R1 carb due to its reliability, smooth fueling, and the provision of a throttle position sensor as standard. Photo: Bogg Brothers

Imagine my surprise to see classic car owners turning to motorcycle carburetors as cheap, relatively easy, and often better alternatives to the antiquated stock units that originally came with their car. Carbs like the Mikunis I currently have can get out of tune easily, and don’t flow nearly as well as modern bike units. There’s some fabrication work that needs to be done to fit bike carbs to cars – mainly creating or modifying an intake manifold – but old car owners should be used to fabbing up a part or two to keep their cars running.

The benefits of fitting bike carbs to cars are numerous. Besides the inexpensive parts availability of old motorcycle carburetors, the more modern and more efficient design of constant velocity (CV) carbs results in better throttle response and drivability. Assuming the fuel metering – which needs to be adjusted as the carb transitions from a life on the vehicle it was intended for to a completely foreign one – is perfected, the result will be better fuel economy as well. Another benefit is the smaller physical dimensions of a bike carb compared to many car units. For those who like to stuff big engines into small cars, utilizing available space is important.

For my 510, as well as other vintage four-cylinder Japanese cars, a nice street setup involves a 40mm sidedraft carb (45mm for a hi-performance engine). For reference, the 1998 – 2001 Yamaha R1 carbs feature a 42mm body with a 40mm choke. Meaning, right out of the box, the R1 units are in the ballpark. Only the jetting would need to be fine tuned. Certain Harley-Davidson units are also said to work but are not recommended since the V-Twin only ran one carb, meaning, depending on engine application, at least another unit would have to be sourced, mated together on an intake manifold and synced together. The extra effort simply isn’t worth it.

Tight squeeze? Try a pair of sportbike carbs.

Tight squeeze? Try a pair of sportbike carbs.

I personally haven’t driven a car with motorcycle carbs fitted to it, but considering the fuel economy benefits alone, the thought of getting similar performance as my current setup while using less fuel is intriguing. Besides, it’s a clever way to combine my two-wheel and four-wheel worlds together.

Generally speaking, I’m used to seeing the latest car technologies trickle down into the bike world – EFI, ABS, cruise control, traction control, etc. – but I can’t remember a time when the sharing of technology has worked the other way. I’m delighted to see old bike parts can be put to use on even older cars.

Hey Burns, mind if I borrow your bike for a little while?

Hey Burns, mind if I borrow your bike for a little while?

However, come to think of it, carburetors themselves are a dated technology. Maybe my next trick will be ditching the 40 year-old engine I currently have in the 510 and massaging in a tricked-out, fuel-injected Hayabusa engine!

Man, I really need to stay off the forums…

  • Reid

    The 510 is one of my favorite cars of all time. I encourage you to swap in a souped-up Hayabusa or ZX14 lump! Actually, I’m surprised that more kit cars or small production sports cars don’t use versions of motorcycle engines.

    • TroySiahaan

      My long-term plans for the engine bay involve something with a little more torque. And my guess is adapting a bike transmission to an automotive setting is the prohibiting factor for kit car usage. Not that it can’t be done, but there’s a plethora of car engines/transmissions already out there.

      • Kevin

        Troy, I suspect that the answer to your idea might be found in gearing: With the plethora of 7, 8, and 9 speed automotive transmissions available today and some manipulation of ring and pinion gearing in the differential I think it could be accomplished, especially to consider the RPM a ‘Busa or ZX 14 mill will turn:
        Truth be told though, if I had one of the Japanese 2002s of yours I would be considering swapping in a massaged VW TDI motor:

        • sgray44444

          Has anyone tried a 215″ V8 aluminum Buick / Olds motor in these?

          • Kevin

            I don’t know: I have been told that the VW VR6 motor which is a narrow angle (26 degrees) V6 is too wide:

          • TroySiahaan

            Yep. I’ve seen this exact swap done before.

          • sgray44444

            It’s common in small British cars, so that doesn’t surprise me. It’s a very small and light V8 that can be stroked to get 305 cubic inches.

        • http://www.bikebd.com maxman

          Bangladesh is a country where day by day motorcycle is becoming a part of culture among the youngsters. Last year around this time Rasel Industries Ltd.
          brought Lifan KP150 and this year they are going to update us with the sports version of it. It’s Lifan KPR 150 , the water cooled racing version.

          See More

      • James Stewart

        As mentioned above – just go buy the GM connect and cruise LS3 package – 6.2L/430 HP/Yard-Tons of torque. Peter Brock has a small block in his 510 – you can run him for pinks with your LS3.

  • Steven Holmes

    I’ve heard of folks stuffing ‘Busa engines in Smart cars. don’t see any reason you couldn’t stuff one in one of your 510’s.

    • TroySiahaan

      Sure it’s possible, but I’ve got my eyes set on something with a little more torque. :)

  • Breaker Morant

    What’s next? SU and Weber on Vespa? How about a Holley XP on a Burgman…. sounds promising! I know Mikunis have been replacing SU’s in Swedish Bricks… this is getting too esoteric, love the sound of a punched Holley!

  • sgray44444

    Why bother with carbs? Use the throttle bodies instead and mate it up with a Megasquirt efi controller, and tune from your laptop. Of course you will need a new electrical fuel pump, regulator, and possibly return fuel line, but the car will always run well and the mileage will be even better. You can also use it for programmable spark control with a crank trigger wheel, getting rid of your distributor.

    • TroySiahaan

      You kinda answered your own question: “Of course you will need a new electrical fuel pump, regulator, and possibly return fuel line,” followed by, “programmable spark control with a crank trigger wheel, getting rid of your distributor.”

      Retrofitting an old car with modern tech is a lot of work. Some people are old school and just prefer to keep it simple. I like driving my car more than tinkering with it. Of course, I’ve done neither lately…

      • sgray44444

        I understand, but I think the effort up front pays off later.

  • Reid

    While this is, of course, a motorcycle website, there really is no better swap option for the 510 than something from Nissan’s own SR or even RB family of engines. A friend of mine from Orlando had a 710 with an RB25 turbo and it was a hoot to ride in. However, another incredible option is the ever-available Chevy LS2…six liters is hard to beat.

    • TroySiahaan

      Yeah this is a motorcycle website, but I like cars, too. The RB is a great engine, but it’s too long and won’t fit in a 510 w/o some major firewall cutting. Great swap for a Z car, though!

  • http://www.bikebd.com maxman

    Bangladesh is a country where day by day motorcycle is becoming a part of culture among the youngsters. Last year around this time Rasel Industries Ltd.
    brought Lifan KP150 and this year they are going to update us with the sports version of it. It’s Lifan KPR 150 , the water cooled racing version.

    See More