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Motorcycle projects

Honda CB400N -83 rebuild

After rebuild, 2015 One Honda CB400N 1983 was found in a garage just outside Lerum in autumn 2016. This was a running bike, it was dyrty and in a terrible condition but after a test ride I decided to buy it.

The whole bike was taken a part and cleaned, rust was taken care of and a frame repaint was nessecary. The motor was taken a part and cleaned, valves where adjusted, clutch was replaced and sprockets and chain replaced. The fork was reconditioned, brakes reconditioned with new pads and new fluid. New tires and painting of the frame. A complete makeover regarding the electrical system. The seat was a terrible home made heavy steel construction that needed a replacement. Rear fender was missing and replaced by a fron fender from a HD.

The basic engine formula, a very over-square twin-cylinder motor relying on chain-driven counterweights to balance out most of the vibration inherent in a four-stroke twin. Honda's three-valve-per-cylinder layout, as on the Civic car engine, and the engine breathes through two 32mm Keihin constant vacuum carburettors to give a claimed 43bhp at 9,500rpm and 24.5ft-lb of torque 1,500rpm lower down the scale. Straight-cut gears transmit the power through a 14-plate clutch running in engine oil.

From side to side through a series of bends is no problem due to the low weight and the bike's agility, and one of life's pleasures is picking the Honda up from a left-hand bend, leaning hard into a right-hander and changing up through the gearbox. The engine is strong enough to pull a high gear through most bends, but the top three ratios in the six-speeder are close enough to make their efficient use a source of real satisfaction. The gearbox itself is smooth and the ratios fast and easy to select, with no risk of missing a change, but because of the relatively modest power output of the engine you need to avail yourself of the 'box' to get the best out of the machine.

Braking is superb at the front and pretty awful at the rear. The twin front discs have their calipers behind the fork legs in the current fashion. One finger is all that is needed to produce tyre-howling stops, although using four fingers gives more sensitive control. But the rear drum, although rod-operated, offers no feel whatsoever on my bike. Great pressure is needed to achieve any retardation from the back brake, and there is no telling at what point the wheel would lock up - which it would do, often unexpectedly. The front discs deserve to be backed up by an efficient rear drum. Wet braking caused no bothers. Drum brakes in rear was ok 1982 but today.....

Driving in town traffic the Honda has a light and quick steering, a feather-like clutch action, great braking, and a docile disposition. Yet it has all the urge it needs to stay ahead of most traffic, excluding riders of larger motorcycles. Neutral is easy to find at a standstill, although six gears seems a real overkill when you have to change down five times approaching a red traffic light. My ankle does not get quite convinced that so much frenzied activity should be necessary.

The major electrical components and the battery live behind the sidepanels. The air filter is a washable polyurethane foam type, which cut servicing costs. Being a single overhead cam engine, tappet adjustment present few problems, the whole rocker box comes away with two bolts, while the electronic ignition removes yet another chore. That leaves just changing the oil and balancing the carbs as regular service items, and the oil drain plug is readily accessible.

Mechanical noise on the twin is very low, and generally it has all the appearances of being very easy to live with. One annoying trait that seems characteristic of the models from this time is a high degree of drive-train lash which is compounded by the sudden on/off action of the CV carbs.

This is a great little bike, very fun to drive around the roads close to my home in Kungsbacka.

Before restoration, 2016

After rebuild, 2017

Before restoration, 2013 After rebuild, 2017
During winter 2016/17 I customized and repainted.
Some of the customization:
  • Raask rearset
  • TT handlebar
  • Mini turn signals including electronic flash relay for LED
  • Motad 2-1 exhaust system
  • Chain guard in stainless steel
  • rear fender picked from an old HD
  • Solo seat in glassfibre
  • New paint, "Ice White" by volvo, painted by Universal Teknik
  • Honda decals

    A lot of pictures was taken during the build, you can watch them all in the album or here: