How he converted a Royal Enfield to diesel power

"It is a Royal Enfield with a diesel engine shoehorned into it."

A 2008 Royal Enfield Electra neatly converted to diesel power is for sale on eBay in New Jersey. It has electric start and kick start, a five-speed gearbox changed to shift on the right side, and a top speed of about 52 mph.

"This is a crude rough ride that will get attention and is a blast," the seller writes.

"If you ever dream about blasting into town on a tractor/rocket hybrid, this will fit that need. Am I the only one? We will find out with this auction."

Diesel cooling fan and shroud are distinctive.

The ad describes the largely stock Royal Enfield motorcycle and its rebuilt Lombardini 6LD360 air-cooled, single-cylinder diesel motor.

I wrote the seller to ask for more information about the challenges he faced in making it.

But first: why do it?

"About three years ago I really wanted to import a Royal Enfield Taurus diesel from India, but it was just dead end after dead end, so eventually just did it here and was able to get past all the issues/shortcomings of the Taurus," Anthony wrote me.

Diesel retained its own muffler and the stock Enfield muffler.
Note right-shift conversion, done to improve shifting..

In his ad he wrote: "I got the 2008 Enfield on a trade, took it for one ride with the stock 500 engine, came home and went 'meh.' The stock Enfield gave me no feeling..."

But "the Enfield was the perfect platform for swapping in a diesel engine, with the separate five-speed transmission; the main hurdle was making the adapter to mate the primary to the engine block — and about 100 smaller issues that were sorted out.

"Engine has electric start and starts with the stock starter button on bars, and has the kick-start as well just in case, but the upgraded charging system on the engine maintains the battery well.

Front disc brake is welcome as the diesel motor adds weight.

"I chose the Lombardini 6LD360 engine since I restore Italian tractors as a side gig, and have a lot of experience with that particular engine. Fully mechanical, parts are cheap, and easily rebuildable. Plus I had some extra engines laying around...

"That big plate on the bottom is a large capacity oil sump with cooling fins that I transplanted from a different engine; more oil capacity and better cooling. Overkill? Yes, maybe, but the bike was originally intended to be more of a scrambler with knobbier tires for some light off road and trekking, so slow moving — I wanted better cooling for longer life."

Big plate on bottom of motor is extra-capacity oil sump with cooling fins.

The motorcycle has effectively two mufflers, retaining the Lombardini box muffler and the Enfield muffler "to keep exhaust tone reasonable. The motor has a decompressor lever. Its electric starter is integral to the diesel motor, not the Royal Enfield's original.

"It will not go on highway geared as-is," Anthony wrote in the his ad. "Would need to change rear wheel sprocket to get highway speeds. Bike with current gearing runs at 52 mph, and has tremendous torque down low. Original intent was to make it a scrambler, but after it was running and on the road kept it as it is."

Air cleaner and spin-on oil filter keep "Dirty Diesel" clean.
Fitting stock primary was the most challenging element of conversion.

In an email to me, he added this:

"About the gearing — I originally had very tall gearing for the bike to do 70, but within a week I burnt the clutch plates out. It was just too tall to pull away and the torque of the diesel was way too much for stock plates. So ordered heavy duty plates and springs from Hitchcocks, and lowered the gearing, so now its very easy to pull away and ride around but the top speed is limited to a little over 50. My next step was going to be new rear wheel sprocket and O-ring chain, but I got other bikes to feed.

"The engine is heavier than the stock RE 500 gas motor. This is an understatement. The engine is indestructible and weighs like it is.

"Shifters, foot rests, rear brake were all slightly modified... The right-side shifting is so much more exact; the American left-side shifting has the long cross shaft and a long foot lever on the end of it, any play is magnified and it feels so sloppy and false neutrals were common.

"Getting a false neutral while downshifting for a red light on a 500-pound diesel British bike is frightening. So switched to right shift and all was resolved," Anthony wrote me.

"This bike is titled, registered, insured, and running on the roads in New Jersey," his ad notes. "There are not many street-legal diesel bikes in the U.S."

Here's his video of the motor running.

A close look at Royal Enfield's diesel motorcycle

Royal Enfield sold this diesel powered Bullet in India.

An original Royal Enfield diesel motorcycle for sale in Austin, Texas, offers an especially good look at this motorcycle, which is very rare in the U.S.

It has a 325cc Greaves Lombardini motor, said to be good for about 6.5 horsepower, half that of a gasoline powered 350cc Bullet.

With its separate gearbox, the old Royal Enfield Bullet has been a popular candidate for private conversion to diesel power. But in the case of this motorcycle, Royal Enfield India itself got into the act, selling its own diesel Bullet, often called the Taurus.

Dieselbike.net once referred to it as "probably the most massed produced diesel motorcycle to date."

The Royal Enfield Taurus diesel motorcycles came with either a 325cc or 436cc single four-stroke Greaves engine, according to that website.

This Royal Enfield diesel isn't labelled a Taurus but graphics are unmistakable.

"Mine does not say Taurus on the tank. I used that in the listing for reference to the diesel model," the Texas seller wrote me in an email.

"I haven't ridden it for three years. It now is hard to start (kick only). When it was running it got a lot of miles per gallon. I don't know what it was but a gallon of diesel would last a long time.

"I have never run it on processed French fry grease but the previous owner did. I think 55 was max speed."

This Enfield diesel has a neat, factory built look.

Although not labelled "Taurus" on the tank, it's apparent from photos on the Internet that his diesel Royal Enfield shares the look and graphics of the genuine Taurus. Perhaps the Taurus name came along as marketing efforts picked up speed.

Although licensed as a 1969, the Texas motorcycle has the rectangular turn signals (sprouting from the nacelle in front) that mark it as a Bullet of the early 1990s.

Diesel motor is air cooled and kick started.

BikesIndia.org says the Royal Enfield Taurus with 325cc Lombardini motor was launched in 1993.

Motorcycles with similar graphics offered for sale around the Internet are said to date from as late as 2002. That's apparently when air pollution regulations in India killed the diesel motorcycle.

Not everyone liked the industrial look of a diesel motor.

Prior to that, the low cost and good quality of diesel fuel, and familiarity with small diesel motors in India would have made even such a low powered motorcycle appealing. They were criticized for vibration.

Jorge Pullin has an extensive article on Diesel Royal Enfields on his My Royal Enfields blog.

Catalog style photo of a later Enfield diesel with Taurus on the tank.

Riding out to help the planet on a Royal Enfield diesel

A diesel Royal Enfield takes on a global issue at its own, slow, pace

Two young men are riding a diesel powered Royal Enfield motorcycle through the Northeast United States talking to the people they meet about climate change.

Erik Fyfe and Albert Thrower, friends since sixth grade, post video interviews they conduct on the blog Slow Ride Stories. They kicked off the trip with a sail up the Hudson River on a sloop, motorcycle and all.

Sailing seems environmentally friendly, and the two riders are pleased when they find bio-diesel fuel for their Royal Enfield.

The 9-horsepower diesel, loaded with two people, video equipment and pulling a trailer, required a push to get up some hills.

Diesel pulling a trailer required a push to get uphill.

Climate change is political poison in the United States, with most politicians anxious to avoid addressing it.

Erik and Albert obviously lean toward the view that we'd better not ignore it. They're out to get people talking by asking what they think, even if it means Albert has to get his ponytail cut off so they can chat up the hair stylist.

 "The only way we're going to be able to do something about it is if we figure out how to engage everyone into this conversation. So going and talking to random people on the street is a little bit of an experiment, to test out what's it like to try to talk about this kind of difficult issue that maybe makes some people uncomfortable, because it is so politicized. And, then, to figure out what people know about the issue, and what might be some effective ways to talk about it," Erik says.

They have a sense of humor, the scenery is beautiful and there's that Royal Enfield diesel motorcycle to root for.

Rider reports 168 mpg on Royal Enfield

To make it from Mexico to Canada on only 10 gallons of bio-fuel, motorcyclist Geoffrey Baker will have to average 170-180 miles per gallon (see previous post) on his diesel powered Royal Enfield Bullet.

"A test run this morning got me 168 mpg... so I'm getting there!" he reports. Baker hopes to start his border-to-border road trip around Aug. 1. He envisions a ride of about 1,770 miles border to border.

Among his sponsors are:

Motogadget, supplier of custom motorcycle electronics.

Motion Pro, maker of motorcycle controls and cables.

Grecycle, biodiesel manufacturer of Tucson, Ariz.

Classic Motorworks, the U.S. importer of Royal Enfield motorcycles.

Carroll Stream Motor Company, supplier of Yanmar engines and parts.

His ride will be covered by Overland Journal magazine.

Border-border challenge for Enfield diesel

Geoffrey Baker plans to ride his diesel powered Royal Enfield motorcycle from Mexico to Canada on only 10 gallons of biofuel. He tells me is still aiming to start the trip around Aug. 1.

Baker, a freelance writer and web designer in Tucson, Ariz., plans the trip "to promote awareness of fuel efficiency," according to his web site.

"It's time to get serious. If we are to continue to enjoy our lifestyle without paying a heavy price in pollution, environmental degradation, global climate change... we will need to be far more efficient than we are today."

His route will cover as much as 1,700 miles and, at 170 miles per gallon, will prove "we can do it!"

Baker says he already has overcome one challenge: finding biodiesel stations along the projected route.

"With an expected 700 miles per tank range, I only need a couple of stations! Still, I'm planning on stopping quite often for biodiesel so that there is always plenty of fuel in the tank.

"Mostly, it's a camping trip, but I may sneak into a motel every now and then for a good hot shower and a comfortable bed; to say nothing of wireless access so I can upload stories and pictures!"

Baker describes himself as an avid diver, skier and hiker. He is also an avid Royal Enfield enthusiast, and is president of the Royal Enfield Association in the U.S. But he describes his mechanical skills as only those of a "tinkerer." Royal Enfield does not build or sell diesel powered motorcycles in the United States. Baker had to build his own.

He started with a 2000 Military model Royal Enfield Bullet, a diesel generator motor purchased on eBay, and a frame conversion kit purchased from England. Older Royal Enfield Bullets lend themselves to such conversions, because they have a separate gearbox; you can change the motor without affecting the transmission.

Baker makes the work he did sound simple, but he couldn't hide his frustration when he took the motorcycle to the Department of Motor Vehicles to register it.

"Here's how it works," he wrote on the Classic Motorworks Community Forum. "To get a Level 2 registration, you must bring the complete bike to the DMV for review. To complete the bike, I must remove the VIN plate in order to weld in the new engine frame. By removing the VIN plate, I am committing a Class 5 Felony, so I can't do that. So I can't bring in a completed bike. So I can't get a Level 2 registration. Wonderful, isn't it?

"We managed to do a workaround. The head DMV Level 2 technician came out to my car, took pictures of the bike frame, the old engine, the new engine, and wrote down all the plate numbers. Then HE chiseled off the VIN plate."

Here's the budget for the project:

Biodiesel Motorcycle Recipe:
1 Royal Enfield motorcycle, any year. $500-$3,000 depending on condition.
1 diesel conversion kit including engine mount, from Henry Price of PriceParts, in England $800.
1 Yanmar diesel clone, 10hp variety – you can find one on most midsized electrical generators. $450-700.
Some wires and tubing $100.
And a couple months worth of evening project sweat equity.

Mileage, not diesel power alone, is Baker's aim. So he did not stop with the motor conversion but has been experimenting with another energy saving modification: water injection from a reservoir mounted on the rear fender.

Tinkering is one thing; lots of people do it and Royal Enfield motorcycles encourage an owner to experiment. But Baker's proposed border-to-border ride is a real challenge, with very little room for the mishaps normally encountered on any road trip. If he makes it he will have proven a point, if not about fuel mileage, than certainly about his willingness to try.

Royal Enfield: 100 miles per gallon

Tucson resident Geoffrey Baker describes what happened when he first rode his Royal Enfield Bullet Military around town. Everyone who has done this will recognize the phenomenon he observed:

"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. "

Geoffrey goes on to describe how he converted his Bullet into a bio-diesel powered motorcycle in Tucson Weekly. He claims more than 100 miles per gallon.