1973 Kawasaki H1D 666

2018 Gareth Harford & Drive-My

No one man has a monopoly on DIY multicylinder conversions. Roger Ramm quietly went about converting his H1D from a 498cc triple to a 666cc four mainly in his garden shed (and partly in the London Underground machine shop). Here’s how

Beastie Boy

1973 Kawasaki H1D 6661973 Kawasaki H1D 666

They say motorcycles are like their owners and, in Roger’s Ramm’s case, it’s true. His originally-owned, homemodified, four-cylinder, 666cc 1973 Kawasaki H1D has been smashed-up, rebuilt, tuned, drag raced, stored, restored and pretty much sawn in half before being re-assembled.

So has Roger, and in exactly the same order – he’s gone through the kind of health problems that would defeat lesser men, but he’s still dutifully rolling his own, full of yarns about riding adventures past and present, and getting ready to ride to the Classic TT on a Honda CB400 grey import. When he’s not doing any of that, he’s restoring and fettling 1970s air-cooled, two-stroke Kawasaki triples – with the H1D taking pride of place. Its four cylinders displace 666cc (naturally, Roger named it Damien) – yes, that’s four cylinders not three.

And he built it in his garden shed. And spare a moment to gawp at the shed (overleaf). Lathe, oxyacetylene gas bottles for welding, racks and racks of spares and springs and bits and bobs, and a goldmine of Kawasaki two-stroke triple parts; head and barrel fins poke out randomly from under Roger’s benches. “I decided to build the shed 20 years ago when I was pissed round the pub,” he says. “Ordered the wood the next day, and me and two mates screwed it together. Can’t believe it’s lasted this long. Seen some action in here.”

Even stuff Roger builds when he’s three sheets to the wind can’t help but survive. Roger is a retired machinist: “I was a fitter and turner for London Underground for 44 years. I had the use of CNC machines, so at least I could put my initials on Damien’s engine cases.” Roger bought the H1D on the 9th July 1973. “I picked it up from a shop called Read Titan in Leytonstone when I was just over 18. I came up Leytonstone High Road like a lunatic. Five weeks later I hit a car head-on in Enfield Town and nearly wrote myself and the bike off. I made a mess of it – there’s still a mark on the frame that shows through.” It took eight months to get back on the road.

The rebuilt Kawasaki was only standard for a couple of weeks before Roger went drag racing. “Raced it for years,” he says.“Up at Santa Pod andAvon Raceway – I added a fairing, Denco race pipes and 34mm roundslide carbs, then I started porting it myself because I couldn’t get a set of Denco barrels – when I think about it, I was chucking stuff off it left, right and centre to make it lighter… like the exhausts; they were brand new and I sawed them in half and put chunks in the bin each week – my mum said,‘Roger, don’t put a whole one in because they won’t take it.’

The best run Roger managed was a 12.18s quarter at 118mph.“That doesn’t sound all that good,” laughs Roger.“They claimed 12.4s as standard but I’d love to see someone do it.” As well as tuning the Kawasaki – which was still a triple – Roger tweaked the chassis, adding a frame cross-brace behind the headstock and cutting off frame lugs. “And then something happened in life and I stopped riding for a few years,” he says.“I stored it in a mate’s garage but he didn’t tell me the roof was leaking and when the bike came back to me, 20 years ago when I built my shed, it was red with rust.

I didn’t know what to do with it.” So Roger started to restore the H1D.“I was trying to get some of the bits back; things like the grab rail. Cost me a fortune and they’re so hard to get, because the D model is a slightly different shape to the other models; they don’t fit.” Did you want to get it back to an exact standard? Roger looks sideways at me.“Well, it’s got four cylinders and six-pot calipers, so no. But I wanted to keep it looking right.” It was the 1990s, and Roger had noticed a few stories of other people adding cylinders to bikes.“

And, when I was a kid, I watched the two-stroke Grand Prix bikes, like the inline fourYamahaTZs. I always knew I wanted an inline four two-stroke.” Roger asked a well-known tuner to try the job first:“I won’t mention his name. He hadn’t lined up the two crankcase halves so the bearings weren’t lined up.And I told  him to make it fire 1-3-2-4 but he did it 1-23-4. It lasted 78 miles before blowing up. So then I decided to have a go,” Roger says. “At the time I had access to the workshop at London Transport. I had the knowledge, and I used all their equipment.”

Now, I’ve always wondered when people talk about ‘adding cylinders’. Like, how? How do you actually do it? Roger explains using parts lying around his shed: “You get your original crankcases,” he says. “Then you literally take a bandsaw and cut right across half of number one cylinder, leaving two and a half cylinders left.” What, just cut it in half? “Yes. It was a big bandsaw. Then you get another set of cases and cut one and a half cylinders off the other side. Two and a half plus one and a half equals four.

1973 Kawasaki H1D 6661973 Kawasaki H1D 666

With top and bottom, you now have four bits of crankcase – you machine up a solid steel bar and run it through the crank tunnel, clamp it on, then TIG-weld the outside. My mate, a welding instructor, welded it for me. Let it cool on the bar, take ’em apart, weld ’em on the inside, clean it off – now you’ve got two crankcase halves. I took them down to Acton train works, put them in a huge oven where they were heated slowly over 24 hours, held for 20 hours, then cooled over 30 hours to take the stresses out of the welds. Then I sent off two cranks to SEP in Kegworth to build one with the right firing order.” How did you know what the right order would be? “Any four cylinder will either fire 1-34-2 or 1-3-2-4.

Some guys on the forums wanted me to build a big bang crank, two together 70 or 90-degrees apart, but H1D gearboxes are a weak point and it would’ve been too much. So it now fires every 90-degrees and I got the gears undercut to be safe. It’s been in there 14 years and been all over, so it works. “Then after that you do a gearbox output shaft extension – because the engine is now sticking out to the side by a cylinder too much, so you recentre it by half a piston width; and now the gearbox and rear wheel sprocket don’t line up. Hence an output shaft extension to bring the gearbox sprocket out, using an outrigger bearing.” It sounds well enough – but were you making this stuff up as you went along? “I had seen others.

But I’d never done an outrigger bearing on a gearbox output shaft before, or cut crankcases up. But it’s only basic engineering, it’s no big deal. The really hard bit was fitting the reed valves…” Because the original triple is piston ported… but why need the reeds? “Because a friend of mine got hold of the original works Kawasaki H1R with a brand new set of barrels – so I made a port map from them. A standard 500 triple gives around 48bhp; H1R porting gives a three cylinder 500 around 90bhp.

So in theory four cylinders should make 120bhp. But once I’d built it, the power didn’t start until 6800rpm and it was unrideable. It would either bog down or wheelie. The inlet port stayed open so long at low revs it overpressurises the crankcases and the charge goes the wrong way. So I reed-valved it – the reed blocks were from America, I put ports in the piston skirts, and now the reeds stop the mixture blowing back. I pocketed the reed valve blocks – I used V-Force 3 carbon reeds in it; aftermarket reeds for a Yamaha Banshee quad. “The result is it’s now got some bottom and midrange,” says Roger. “But it still goes off at the top end. But setting the carburation was the hardest thing on the bike.

The build itself took about a year and a half, but to get it running right took another five years or so. It used to go in the naughty corner regularly – I used to think, ‘I can’t be arsed with this.’ Sitting in those boxes on the wall is over £1000’s worth of jets for the flatslide carbs because no-one else had put 32mm TMX flatslides on a 500 engine…” Let alone a 666cc four. “So I didn’t have a base setting. I was buying so many jets; just four needle jets are £24 each so that’s £100 – you put them in; they won’t take them back. So in the end I bought a load of spare jets of different sizes and went and spent a day on a dyno. The bike went from 76bhp to 119bhp. In the end the jets cost me more than the carbs did.”

Roger runs through the rest of the 666 spec: pipes were handmade by a South African called Brausch Niemann in his factory in Wales. They were two grand. The swingarm is made by Higgspeed in Blackpool, who normally made expansion chambers. I wanted a wider rim to fit a better rear tyre; it’s the original hub so Wilde Wheels laced the rim, in my shed.” And then there are the front calipers: made by Pretech, I’m worried six-pots per side is over-doing it. “A lot of people look at it and say it’s over-braked. Then they ride it,” says Roger. Do you let a lot of people out on it?

1973 Kawasaki H1D 6661973 Kawasaki H1D 666

“Oh yes, if I know them and they’re in the Triples Club. I don’t know how many hours I put in on this thing. But it’s so reliable. It was at Boxhill at the weekend. I take it to shows, it was at the Classic TT last year.” Well if everyone’s doing it, why can’t I? Sounds like a good time to sling a leg over the 666…


Basking in the powerful glare of August sunshine, Roger’s 666 glistens in a juicy shade of red. “I’m quite fond of red,” says Roger. I wonder, why don’t they make bikes this colour these days? “It’s candy,” he says. “It’s so brittle, you knock it and it shatters. You have to put a silver or gold matte coat on first, then the candy paint is translucent so it shows what’s underneath. And you change the shade by adding more coats – that’s why it’s such a sod to match.” ’d better not drop it then. And almost as I say it, I go to lean the bike over without the sidestand down properly, and have to catch it as it drops.

Oops. Roger thinks it’s funny, and he’s probably right. The 666 starts second kick: fold the Raask rearset footpeg out of the way, ignition on, remember not to hold the clutch in, and swing – and off it goes, popping and crackling with a throaty gargle. Tickover is clean and even, throttle and clutch feel light (Roger uses a lock-up clutch he made himself), and although gears are racepattern (neutral at the top, then step down for first, second, third up to fifth) the bike handles easily and confidently enough at low speed to leave excess brain space to get the gearshift right.

As the 666 chuckles across town, it’s immediately clear Roger’s years and cash spent carburation tuning weren’t wasted; the Kawasaki fuels as cleanly low down as a modern bike. If you snap the throttle open it’ll sag rather then bog, but with only a modicum of revs the motor pulls cleanly and predictably. And when the tacho hits 6000rpm, it goes proper barmy, tearing past the 8500rpm redline in a matter of millseconds with a shrill, cackling roar – almost quicker than I can change, er, down to go up, isn’t it? It’s controllable and fun.

A flatbed recovery truck pulls alongside the 666 at the lights. The kid driving it looks about 12, but he stares at the inline four Kawasaki with a quizzical look, holds up three fingers and shrugs. I hold up four back, and he looks surprised, then gives me the thumbs up. Ah, a connoisseur. The 666’s handling is sorted. It’s a bit bouncy on the stiffer but mostly ordinary springs – but the BT45s stick, the PreTech brakes are indeed superb with bite and great feel at the lever, and steering is weight-free and agile.

The 666, in contrast to its name and the H1’s reputation, is actually a really easy-going, nice bike – the only thing I can live without are its high-frequency vibes, cruising at 80mph. Apart from that, it seems as if Roger – more by design than accident – has arrived at a stunningly sorted example of the H1D. “I could ride this home,” I say to Roger. “No you couldn’t,” he says.“It’s not for sale. Someone with a lot if money kept offering me £25,000, but I won’t sell it. They’ll put this one in the ground with me.” Except of course, they won’t.

Because these two are born survivors… And not to mention his other bikes – a 1972 H1B, a KH400 made to look like an earlier S3A, and Roger’s first-ever bike: a 1971 Honda Benly C95 154. Not the same model; his actual first bike. He bought it back 10 months ago:“I was browsing a Facebook group one night thinking I’d like to get one again, when I saw a black Benly for sale.

Then I saw the number plate and realised it’s actually my own bike.You’ve never seen anyone hire a van so fast,” he laughs.“I went straight up to the bloke in Derby and bought it, but I only told him why I wanted so badly after I’d paid him in case he put the price up!”



Type air-cooled, inline-four, reed valve, two-stroke
Bore x stroke60x58.8mm
Compression ratio 6.8:1 Ignition CDI
Carburation 4x32mmTMX
Mikuni flatslides


Primary/final drive gear/chain
Clutchwet, multiplate
Gearbox five-speed


Frame steel tube cradle
Front suspension teles, non-adjustable, stiffer springs
Rear suspension twin shock, preload only
Front brake2x296mmdiscs, six-piston calipers
Rear brake1x180mmdrum
Wheels spoked wire rims
Front tyre100/90-19
Rear tyre140/70-18


Dryweight178kg est (392lbs)
Seat height800mm(31.5in)
Fuel capacity15litres (3.3 gallons)
Ground clearance155mm(6.1in)


Top speed115mph(est)
Power 105bhp(est)
Torque 56lb.ft (est)
Fuel consumption28mpg

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