A Trifield? That's not a name you hear too often nowadays. But way back in the 1960s and 1970s, there used to be quite a few of those chugging around—along with a respectable number of Tritons, Tribsas, NorBsas, Norvins, Trivins, Tricatis, and any number of other home-brewed hybrids either hoping to improve the breed, or just trying to be different.

At one time or another, we've pretty much seen them all. But John Dawes's Royal Enfield-cum-Hinckley Triumph Bonneville-powered Bullet is a new one. Can't say we've ever seen one quite like this before.

We would have remembered.

The bike started out, obviously enough, as your common or garden variety Royal Enfield Bullet. This one was built in 1979, which wasn't exactly a vintage year for the firm. Dodgy quality control and dubious engine alloys made for bikes that were definitely cheap, but not always exactly cheerful.

Nevertheless, the basic rolling chassis on any Enfield Bullet isn't too bad if you don't mind a little rough edges and refinishing. This one was found on ebay and had been converted to a diesel engine, which had blown up.

“l really spent too much money buying it,” said John. “In the last ten seconds of the auction, I paid £700, but l have no regrets now.”

It was also on ebay that he found an 865cc Triumph Speedmaster engine, essentially the same as the standard Bonnie lump but with a 270-degree firing order as opposed to 360-degrees.

“The engine came from the United States, Pinwall Motorcycles, actually. They sell them a lot cheaper over there, and for £750 I got the whole lot including most of the ancillaries. lt was sent in the back of a 1950s pickup truck which a friend of mine was importing (a stroke of luck for me). Nearly all the rest of the spares also came from ebay UK and were reasonably priced.” 

Putting it together

John, who lives in Andalusia, Spain, trained as a blacksmith/farrier and learned the art of forge welding, so the welding required for this project presented no real problem. But bringing the engine and frame together in any meaningful way still required a lot of thought.

“Everything more or less fitted,” said John, “but I had to cut away the centre stand and make a new prop stand—which is just the trick. Also l wanted to fit a wider back tyre, and 18 x 120/90 is the widest you can fit without major frame changes. So l modified the swinging arm too, some of which l had to do anyway as the drive chain is now on the right and not the left.

“I guess l could have just bought a frame for a new style Bullet which already runs the chain on the right, but l had time on my side and l like a challenge. In the process, l moved the wheel back an inch or so which has lengthened the wheelbase and given added stability. l also fitted the swinging arm with proper roller bearings and a 17mm spindle from a Yamaha FZR 400. The original was only half an inch in diameter and ran in a rubber bush which l didn’t think was up to the job.

“l tilted the engine forward a bit as l've always liked the look of the Norton Commando. It also helps with the chain clearance which runs quite tight. I had to offset the engine half an inch to the left to get the sprockets aligned, but you really don’t notice it when riding the bike. You could mount the engine dead centre, but that would mean more frame modifications, and Harleys have a far more protruding primary drive case than mine.

“The rear engine studs came from a pit bike but were just the right size. Overall, it was really just a matter of trawling through ebay till I found what I wanted.

"When I was seventeen years old, I had a 350cc Enfield Bullet, but even after fitting a high compression piston, scrambles cams and a big carb, it was a slug. l knew you could pick up lndian Enfields pretty cheaply and reckoned that as the frame was the same as a 1950s 700cc Meteor, it should be possible to squeeze a new Bonnie engine into it.

“To be honest, l didn’t take any measurements before l started. I just trusted my own ability to make and adapt things as l went along.

“l still haven’t done a cosmetic restoration on it. I thought l'd first see how it came out, mechanically speaking. And anyway, l like my bikes to have a bit of an “everyday riding patina” to them."

So how does it ride?

“lt goes really well. It’s a blast. l got the idea when l test rode a new Triumph Scrambler fitted with a loud pipe. l loved it, but thought it was a bit of a heavy lump. l wanted something that went back to the original Meriden Bonnie ideals, meaning nice and light and flickable.

"The Trifield weighs less than 440lbs (200kgs), and that’s tanked up and ready to go, but with that lovely 270-degree engine feel and noise.

“With the engine mounted low, it handles really well, which is what l wanted. It feels something like a Hinckley Bonnie, but lighter and with the scrambler engine. The silencers, I believe, are off a 1960's T120 Bonnie and they sound great!”

Future plans for the bike?

“Perhaps a Vincent-style flat handlebar and maybe convert the front brake to hydraulic operation—although as it stands, it’s much better than my first Bullet’s single sided job. Also, you have to make sure the rear brake shoes float properly. It makes a huge difference because as they come from the factory, they’re bolted solid."