I bought the 400/4 through a private advert in the local evening paper. The bike looked virtually immaculate when I first looked at it, just a little rust on the exhaust pipes and the mudguards. The bike was yellow, 1978, T reg, with 20000 miles on the clock. It had been fitted with a baffle-less Marshall four into one, Boysen ignition, Marzocchi shocks and nearly new Avon Roadrunner tyres. The oil filter bolt was well chewed up, so I guessed the bike might need a good service. When the engine was fired up, the shot camchain rattle was loud. We agreed a price of £350 (a good ’un was worth around £500 in 1984).
As this was my first multi-cylinder bike I took the Honda to a dealer for camchain replacement. He charged me £90, showed. me all the worn parts and told me why the chain had failed so early - if the chain isn’t adjusted regularly it will thrash around and cut into the pivot on the tensioner mechanism. The spring can’t move the tensioner, so camchain play is unchecked. Anyone replacing the chain should check that the tensioner still works or it won’t last very long. The dealer recommended adjusting the tensioner every two weeks.
The oil filter bolt took all afternoon to remove - I eventually had to file two flats to give the mole grips some leverage and whack the bolt with a hammer (sounds more like a big hammer and chisel job to me - Ed). A pattern bolt with a larger nut is available. The valves would have been easy to adjust had not the opening in the cylinder head been so small - the end of the feeler gauge had to be bent at 80 degrees, making it difficult to judge whether the correct gap had been achieved.
During my year of ownership, the bike always started first prod of the starter every morning. The choke was shut off within a few minutes as the engine warmed up quickly. The exhaust (after I’d added some baffles) growled beautifully, giving the impression of a powerful machine. When accelerating, the bike felt much more useful above 5500rpm when it felt most happy.
Performance is quite good, accelerating up to 85mph with ease. The remaining 15mph, to reach the ton, needs a prone rider with a tail wind and a steep hill. Even in 5th, the bike would not reach 90mph on the flat, it just hasn’t the power. I even had the bike checked over and set up expertly by a dealer with a good tuning reputation, but the performance was still the same. I had expected 105mph after reading the tests in various magazines. A VT250 can sail past at the ton and CB250RSs can keep up.
Despite this, as soon as the road turns twisty the CB400F can make up the distance because it handles so well. I could ground the exhaust and footrests and it felt safe and rock steady no matter how fast or whatever the angles of lean, even with leaking rear shocks. Economical the bike was not, averaging only 41mpg. I once rode the bike with great restraint and was rewarded with 43mpg! Normally, I’m a little throttle happy, illustrated by the fact that a DT175 I once owned only did 50mpg when the previous owner was getting 77mpg. Perhaps the jetting wasn’t right for the Marshall exhaust?
The rear drum brake was very good with plenty of control and power. The front disc was just adequate in the dry, but had barely any effect in the wet even with Verrah wet weather pads fitted. Once, approaching the end of a dual carriageway in the wet, I applied the front brake with both hands on the lever. I would have slowed down faster if I had put my feet down, it was so poor. No wonder the pads lasted for so long.
A famous trick of 400/4s is to cut out in the wet, and mine was no exception. I fitted the longest plug caps I could find and sprayed everything with WD40 every two weeks. This cured the cutting out, but if I ever forgot the spraying, the engine would cut out at the first sign of water, rendering the bike immobile.
During the year I owned the bike, I only bought standard service items like oil and air filters. Nothing broke or fell off, it just started and. ran perfectly every day. The rear tyre had lasted 8000 miles with a good 1000 miles still left in it. The drive chain was treated to Linklyfe every three months and didn’t wear much. After 28000 miles the engine was still in good shape with no blue smoke. I sold the bike for £400 to the first of five callers, proving that this model is still in popular demand.
I was very pleased with the bike overall, its lack of top end go being overshadowed by its great handling, looks and solid, well built feel. If anyone is contemplating buying one - go ahead, they are great and one of the few bikes that will retain their value.
S. M. Davis