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Honda CB400F Restoration

Published: 27 November 2015

Updated: 20 November 2015

In 1998, Graham Hugill bought a CB400F that had been lying in bits in a mate’s garden. He spent 30 months restoring the bike, then the next 10 years and 21,500 miles developing the Honda into the bike he always thought it should be…

raham Hugill goes back a long way with Honda 400/4s – back as far as 1976 to be exact. That was the year he bought his first one – SVY 224P – brand new, part-exchanging his CB250 G5 at the start of that famously long and hot summer.

“I just fell in love with the look of the 400,” Graham explains. “I’d ridden a mate’s 750, but it felt so big and heavy. But, to be honest, I think it was the looks of the CB400F that really did it for me. Those pipes, the tipped-up rear to the seat and the glorious sound from the four-into-one exhaust. I used to take mine through a tunnel under the railway, drop it down into second gear and wind it on just to enjoy the noise it made. The whole package was great on the 400/4. The handling was as good as my G5’s was awful, and it felt pretty fast after that 250 too.”

Graham’s love affair with his 400 lasted until 1982. “I’d been everywhere on the bike, covered 30,000 miles and sold it for just £50. That was the worst mistake I’ve made. I had a few other bikes – though none that captured my heart like the 400 – and dropped out of motorcycling when I went to live and work in London in 1986.” But a chance find in a mate’s garden after returning to live in his native Yorkshire gave Graham a second bite at the CB400F cherry. With the bike restored, he started to look at areas where he felt he could improve the bike for the 21st century.

“I really wanted to keep the bike looking standard,” Graham explains. “Apart from the fact that standard bikes hold their value better, I’d restored it because I love the whole concept, ride and look of the CB400. I didn’t want to mess with that. But there were things I wasn’t so keen on and thought could be done better. And, as time went on, there were things I wished I’d done differently. So I started a rolling programme of work to get the bike to where I wanted it to be.”

The first thing to come in for attention was the poor sealing of the carburettor intake stubs. “The ones I’d originally fitted were cracked,” Graham recalls. “I repaired them with epoxy glue and all seemed well. But after about 500 miles and three different types of glue,
I gave up and bought a new set of inlet stubs for £40 from David Silver Spares (01728 833020).”

That set the ball rolling and in October 2004 Graham had the chance to buy up a job lot of spares from another 400/4 owner who was abandoning a restoration project. “I got loads of parts from him,” says Graham. “Most of them I just put to one side ‘in case’, but there was a complete Dyna S electronic ignition system – with coils – and I was getting fed up with fiddling about with two sets of points at service time, so on it went. That was seven years and nearly 12,000 miles ago and it hasn’t been touched since. That’s a worthwhile upgrade.”

A couple of quiet years spent enjoying the bike followed, but in late 2006 Graham started experimenting with LED lights instead of standard bulbs. Although he reverted to standard bulbs for the indicators, he’s stuck with the LED ‘bulbs’ for the warning lights and stop and tail lamps.

“The warning lamps are brighter, so it’s easier to spot when I’ve accidentally left the indicators on and the fact that they draw less current than incandescent bulbs goes a little way to balancing the extra power needed for the 35/35 watt Cibie halogen headlamp unit I fitted when I restored the bike. I kept it from my first 400/4 in 1976,” says Graham.

March 2009 saw the next major round of work, when Graham came across an F2 engine for sale in nearby Holmfirth. “I wasn’t happy with the condition of the engine cases, and I’d read that the F2 engines have longer cylinder/head studs to combat oil leaks from the head of the earlier engine,” he says. “I’ve torqued the head nuts down to 19lb.ft [the standard setting is 14lb.ft] and they’ve given no problems. But really I bought the F2 engine because it was much better cosmetically than the engine in the bike.

“I heated the liners of the first engine in the oven and dropped them into the F2 barrels and honed the bores, before re-using the +0.25mm pistons I’d bought new for the F engine. While I was in the F2 engine, I also fitted new primary-drive shock-absorber rubbers, a cam chain and tensioner blade and a stainless-steel tensioner adjuster bolt and locknut I bought from Phil Denton at the Stafford show. As with the first F engine, the bottom-end and gearbox were fine. It just shows how robust these little Hondas are.”

At the same time as swapping the engine over, Graham took the opportunity to raise the overall gearing, using a front sprocket with an extra tooth and a rear with one less. Later that year, he picked up a pair of used Koni shocks for just £30 and rebuilt them, getting the red springs chromed at the same time. “Even with chroming the springs and refurbishing the Konis, they only stand me at £100,” says Graham.

A final round of work in December saw electrical engineer Graham upgrading the electrics. “I was aware that the output from the alternator was marginal,” he explains. “So I looked for ways to lighten the load on it. In the end, I fitted relays to the horn and both the headlamp circuits (main and dip beam). Not only does that mean virtually the full battery voltage can get to the headlamp, but also the switches get a far easier time as they are only switching micro amps of current. I also fitted an electronic regulator/rectifier unit bought from M&P for £45.”    

Apart from grafting a gel seat pad – bought at the NEC show in November 2010 for £30 – into the seat over that winter and fitting the custom-made front brake caliper pivot pin, that brings the story of Graham’s 400/4 up to date. But of course he’s unlikely to stop there.

“I’d quite like to fit a new loom,” he admits. “But, at £120, they’re not cheap. Still, the peace of mind from having brand new connectors and wiring would probably be worth it.”

A project like this never ends. But, with Graham in no hurry to replace the bike, that’s no big deal. “It does everything I ask of it,” he says. “I’ll keep it until I’m too old to ride. People say that older bikes can’t be as reliable as modern ones, but I rode my first CB400/4 all over the UK and Europe without any worries. And if you restore a bike well and keep it maintained properly, I don’t see any reason why it shouldn’t be just as reliable today. Buy spares when you see them – you never know when you might need them – don’t expect to restore a bike to decent standard on the cheap, and be prepared to take your time. You might have to do a job more than once to get it right.”

Graham makes it sound easy, but then he’s been working on his 400/4 for over 10 years now. But, if you’ve found the bike that ticks all the boxes for you, what does it matter? As he says: “What’s the rush?”

Words: Gez Kane  Photography: Rory Game

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