Green Machine 

What happened when one Tucsonan set out to create a super-efficient biodiesel motorcycle

Let's face it: We're inundated.

Every day, we read about penguins, polar bears, global warming, smokestacks and Chinese smog.

The question becomes: What can we, as individuals, really do? What is the most efficient method of transportation available to me, the consumer?

After a lot of research, I found the answer: I'd have to build it.

So I did. I built myself a biodiesel motorcycle. From day one, I could get 110 miles per gallon With serious modifications, I'm hoping to reach all the way into the 300 mpg range.

Nothing else even comes close in terms of pure, raw efficiency.

It was also cheap. The bike, diesel engine, conversion parts and machine time all came to less than $5,000. If I hadn't made some mistakes (I bought the wrong crankshaft) and hadn't added some bells and whistles, I could have brought it in for less than $4,000.

A motorcycle is far more efficient than a car. My motorcycle weighs 370 pounds, and with a 500 cc engine, it is perfectly capable of highway speeds.

In these days of bloated over-engineering, even motorcycles are affected. Most modern bikes have large engines, electronic systems, voice-communication capability ... hell, you can get one with an airbag. But as motorcycles grow (Triumph recently broke the 2,000 cc mark), their fuel efficiency decreases. Your average Harley will get around 40 mpg. A Honda Insight will get better mileage than your average large American road bike.

But it won't get better mileage than my diesel-converted Royal Enfield 2000 military-model motorcycle.

Royal Enfields are the longest continuously produced motorcycles on the planet. They've been in existence in one form or another since before the turn of the 20th century. They were, in their day, one of the most modern and fastest bikes on the road.

Their day was 1955, and the place was England. That year, Royal Enfield received the largest single motorcycle order in their history, when the Indian army ordered 800 motorcycles.

While big for the Indian market, the Royal Enfield is a small bike by American standards, and its native 70 mpg make it a great choice for fuel-efficiency reasons--and the fact that between 1955 and 2002, the Royal Enfield 500 cc bullet was manufactured virtually unchanged makes it the bike of choice for diesel conversion.

First, the bike (up until about 2003) retained its separate transmission--and gearbox--while virtually all modern bikes are "unit construction," meaning the engine and gearbox are a single piece. With the Royal Enfield, you extract the old motor, insert the new motor and hook up the primary chain to the transmission. Then you're in business, more or less.

Second, as bike engineering has advanced, the frame and engine became one entangled mess, with the frame wrapping around the engine with small clearances. That's cheaper and more aerodynamic, but absolutely terrible when trying to make modifications. The Royal Enfield remains a glorious piece of rotten English design, with a huge wraparound frame you could stash a V8 engine in--and still have room for a glovebox or two.

Third, the engine mount and the bike frame are two separate pieces--so you can remove the old engine and its mount, and bolt in a new engine frame, with extreme ease.

There are plenty of Royal Enfields out there--just not in Tucson or the United States, as I found when I went down to register the original, unmodified bike.

I was told that I would need to show my import papers for the bike. I explained that I had bought it in Las Vegas. But I needed to show that this motorcycle had passed the relevant Department of Transportation and Environmental Protection Agency tests, and they had no records in their books for Royal Enfields.

After consulting with the main dealership in Minnesota, I was able to show that the bike had passed such tests, and I was awarded a Level I inspection sticker and a license plate. I drove around town for some weeks, just enjoying the bike.

The most surprising--and satisfying--part of driving was the reaction. Most people were convinced it was an antique. Once, a man came running out of a house, waving me down. He had recognized the Royal Enfield from the sound alone, the big thump of the single-cylinder engine.

Eventually, of course, I had to buckle down and start the conversion.

I read the EPA regulations, and Tucson has no emission standards for motorcycles. However, I was going to make modifications to the frame that required careful negotiations with the Motor Vehicle Division. Otherwise, it was explained to me, I could be found guilty of committing a felony.

I took the bike (in parts) to the MVD to start the process. They told me I needed to come back with the finished product. I explained that in order to make the conversion, I needed to remove a section of the frame that contained the stamped VIN plate. They told me that it was illegal for me to do.


Solution: An MVD official personally removed the VIN numbers, after photographing all the numbers and stamps on the bike frame and engine. Then I went home and went to work.

I cut the downtube off, about 9 inches short of the original. Then I welded on an engine-support frame I purchased from an Englishman named Henry Price, who also sold me all the remaining parts I would need for the conversion (a fuel filter, a new drivetrain case, an extended gearshaft, cables, hoses and primary gear). If you aren't up for some fairly simple welding, you can get somebody to do this part for you; everything else is pretty simple wrench work.

Installing the new diesel engine (purchased through eBay from Puerto Rico) was fairly straightforward. I placed it on the new engine frame, squared it up to the old gearbox and drilled holes for the mounts. Then I bolted the engine in, added the new primary case and put in the replacement main gear and the gearbox/gearshaft; finally, I put on the chain.

Next, I had to set up the fuel system, which meant connecting the gas tank to a fuel filter and new hoses to the fuel pump and injector.

Lastly, I had to wire it all together ... and then I started her up.

The diesel really needs a bigger battery, because it's harder to turn over (higher compression) and draws more power (starter motor via the old kickstart), but I was able to start her by keeping the decompression lever on while revving the starter motor. Once the engine was turning over at a high speed, I let off the lever and chug ... chug ... chug ...

Two minutes later, I had to turn the bike off, because I was surrounded in white smoke.

She's running well now. After a couple of minutes, the smoke drops off, and she idles very well. I'm fine-tuning the fuel system (she leaks a little, and I don't know why) and have yet to get her onto the road. I still have to get her reregistered back at the MVD.

I know for a fact that the Green Machine will get somewhere between 110 and 170 miles per gallon as it stands. But there are ways to improve that.

A windscreen adds to the aerodynamic quality, so I added a small windshield. A full fairing would do even more, but that's for later on.

Removing weight from the bike will improve its mileage. I've already gone from a dual seat to a solo seat, and for daily driving, I'll take off the panniers as well.

The single biggest addition that will increase mileage: the addition of a computer capable of tracking real-time mileage. Called a Veypor motorcycle computer, it has three-axis accelerometers that can give you reams of data.

I've also made some changes to the engine to improve performance. Bruce at Doc's Engine on South Craycroft Road "pocket-ported" the head to improve air and fuel flow, and added specialized coatings to the engine. Mark at M & J Dyno and Machine on South Dodge Boulevard had a whale of a time trying to balance a one-cylinder diesel crankshaft, but succeeded, which will also improve the engine handling. We shaved some weight off the flywheel in the process.

I'm planning on playing with a couple of other improvements, including vapor injection--the addition of small amounts of water to the fuel/air mix, which improves performance and efficiency by somewhere between 5 and 20 percent. There is also supplementary oil cooling--using the electrical power of the generator to power a scavenge pump which sends the engine oil out to a cooler. This may improve efficiency, but probably not by much. This will be my last improvement, if I choose to make it.

The last great benefit of the Green Machine? By using biodiesel, I'm using a "carbon-neutral" fuel source. The downside of using food for fuel is, of course, that it increases the price of food, and uses up land that could feed people. But scientists are working on biofuels based on arid-land crops that could be grown where we farm nothing now.

So tomorrow, if you see a cloud of white smoke and hear what sounds like a very large cement truck on two wheels that smells like a Fry-O-Later ... that will be me.


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