Honda-SOHC

When the great day arrives you can get the taxation class changed at a post office.

On a related note Pyramid do a kit which has both the fork oil seals and the seemingly more elusive dust seals too.

I got mine from Amazon.

A couple of weeks ago, while I was sorting out an ignition problem, I also decided to change to a contactless electronic system. I chose to go with the Boyer Bransden unit, Kit 00089, which is listed for the CB400F and CB750F but, with advice from this forum, I assumed it would fit my 350F too. It cost around £130 with carriage.

Mounting the small electronic control box took most time but I finally fitted it under the frame below the seat nose using Ty-Wraps.





Fitting the rest of the kit was no problem. The whole points backplate is removed. The advance unit is taken off so that the springs and bobweights can be removed then it is refitted onto the crank. The Boyer Bransden unit has a built in electronic advance curve so the bobweights and springs are no longer needed.The circular circuit board replaces the original backplate and the magnetic rotor bolts onto the remains of the advance unit. The original wiring loom can be used but I made up a new loom as far as the connectors under the air filter box.





Like all aftermarket ignition systems the BB unit is designed to work with the stock coils. I checked these and found that they had a primary coil resistance of 4 ohms. I had suspected a coil fault so I was replacing them with new coils from DS Spares. Fortunately I also had the presence of mind to check the replacements which was just as well as they only had a 2.2 ohm primary resistance which would have drawn far too much current through the BB electronic box. After checking with BB I used a couple of 1.6 ohm ballast resistors, one in the power feed to each coil.






The initial set up, described in the instructions, gets the bike started then you can use a strobe to accurately set the timing using the full advance timing marks.

An interesting feature of the BB ignition is that, with two pick up coils replacing the contact breakers and TWO rotating magnets replacing a single cam lobe ALL four plugs fire together all the time

I contacted Boyer Bransden to find out the thinking behind this and they said

"There are a few reasons. Its more accurate, once its completed one revolution, the system will find a central point for sparking and that will never change. Because of this, it makes setting up much easier and can be done on any cylinder. It also burns un-burnt fuel ready for the next firing stroke which improves the running and emissions of the engine."

I have had the bike out a few times with this system fitted and it is a definite improvement over the old (and possibly a bit iffy) coils and contact breakers. It is smoother and more tractable at lower revs (probably due to the slower advance curve) and definitely pulls better at high revs too.

RS Paints are very good at supplying motorcycle colours.

It's taken a week but I think I'm back to making forward progress.

I replaced the lost side panel logo with a new aftermarket one from David Silver. Unfortunately it is a stick-on like the one which fell off. Strangely, when I had a close look, the badge had been moulded with the original mounting pins in place then these had been cut off to allow the double sided sticky tape to be used.

I also replaced both coils with new aftermarket ones from DS Spares. These bolt straight on in place of the old ones and have extra long plug leads which you can cut down as required.

I also decided, while I was sorting the ignition, to change to a contactless electronic system. I decided to go with the Boyer Bransden unit. Kit 00089 is listed for the CB400F and CB750F but correctly I assumed it would fit my 350F too.

I managed to mount the electronic box under the frame below the seat nose.



The rotor attaches to the mechanical advance unit AFTER the bobweights and springs are removed and the circuit board replaces the points back plate.



The Boyer Bransden unit has a built in electronic advance curve so the mechanical unit is not needed.

Like all aftermarket ignition systems the BB unit is designed to work with the stock coils. These have a primary coil resistance of 4 ohms. Fortunately I had the presence of mind to check the resistance of the replacements which was just as well as they only had a 2.2 ohm primary resistance which would have drawn far too much current through the BB electronic box. After checking with BB I used a couple of 1.6 ohm ballast resistors, one in the power feed to each coil.



The initial set up gets the bike started then you can use a strobe to accurately set the timing at the full advance marks.

Thankfully it fired up a treat on all four cylinders and drove very well.

An interesting feature of the BB ignition is that, with two pick up coils replacing the contact breakers, and a single rotating magnet replacing the cam each pair of plugs would fire once per crank revolution BUT the BB unit has two rotating magnets so all the plugs fire together twice per engine revolution.

I wonder what that does for plug life?

I got these from RS Components.



There are five 0.002" feeler gauge strips about one foot long.

They cost £10.49 with free carriage.

You can get them in most thicknesses and at this price you can experiment by cutting or bending a few till you get the perfect shape.

I've never had a 400. To be honest I was never keen on the styling.

Performance is limited as it's a heavy 350 and I'm a heavy bloke. It's more like riding a 250 really but the sound of the 4 pipes is brilliant. Especially on the overrun