Topic: 1975 Honda CB400 Four Supersport Cafe South Africa - #SuperTramp

[Leonardovans]

I think either my method is wrong, or the book is wrong. I cannot get F1.4 to line up with removing the blue wire and yellow wire the test light method. Or my points are gone.
I am so fedup now I am going to buy an electronic system.
I am looking at a complete system with ignition, plug wire, coils etc.
Any recomended suppliers?

[calj737]

Are you static timing the bike? Can you shoot a picture of the points plate too?

[Leonardovans]

I am using the test light method.
Set the gaps
Disconnect the blue wire.
Switch ignition on.
Attach test light to ground and other side to blue wire.
Turn crank
Light comes on where the two small marks are before the F mark and stay on.
If I turn the poins plate nothing happens.
I have two complete plates.
Switched out both.
Same thing.
I can only send a pic tomorrow as I am in my phone.

[01Thomas]

This is Completely Wrong!

The correct description is:
T = Top Dead Centre
F = Fire (at idle, or static)
Further on (about 10mm, after the numerals 1.4 or 2.3 respectively) there are two further marks which look almost like a " with about 1mm between them.    Those are your Full Advance marks. Try and line it up between those two marks.
Most people do indeed time it so that full advance occurs at about 3000 or 3500 rpm (I can't remember what it is; check in your manual) using a timing light.
If you don't have a timing light then time it statically using the F mark - that will be good and safe enough to go riding but unlikely to give best performance..

most people recommend setting the Full Advance while the motor is running, then letting the idle be where it is as a result. F mark is full, T is idle. Static timing is a bit trickier and depends upon your method.

[calj737]

This is Completely Wrong!

Yes it is! Sorry, major brainfart this morning. Got distracted while typing this, and never proof read what I posted. Thanks for clearing that up, Thomas.

Here's a picture of what Thomas (and I meant to) to depict with degrees of advance labeled. It's from a 550, but it's still relevant:

[01Thomas]

No worries Cal, we all have one of those from time to time.

[Leonardovans]

Sorry I could not uploaf a pic, super busy day. I just fiddled some more now and I think I might have gotten the timing sorted.
But there is an issue with idling.
So air screws are out 1 turn.
Adjuster screws are out 1 1/4 turns.
I start and she doesn't want to fire.
Then I pull the choke lever up and a quick blip of the throttle and voila.
And she idles.
Then I push down the choke and try to keep her going with the throttle, but she dies almost immediatly.
What the heck is going on?

[01Thomas]

Wait for the motor to warm up thoroughly before pushing in the choke. The best way to warm her up is to ride her gently while reducing the choke progressiely. It can take 5 or 6 kilometres before she's warmed up properly.

[nvr2old]

Wait for the motor to warm up thoroughly before pushing in the choke. The best way to warm her up is to ride her gently while reducing the choke progressiely. It can take 5 or 6 kilometres before she's warmed up properly.

I dunno..my 400F starts immediately with the choke but needs the choke turned off after only about 5 seconds and then idles perfectly...even after months of rest.

[Leonardovans]

I am stripping the other set of carbs and I have ordered my Dyna S.

Lets see what happens.

[Leonardovans]

So I have to measure the shaft diameter for the Dyna because apparently there are two, the later CB400F uses the 750 shaft?

I took three different measurements, but not sure which one to give.

Some help please.

[enwri]

Pretty sure the last picture is the shaft diameter they need.
 The sleeve with the points cam can slide off when you pull the counterweights outwards. new one has to go back on the same way.
remember the orientation of the little mark on the edge of the cam to the timing marks for 1-4. (you have a photo anyway)

[Herr Supersport]

Hi

400 f advancer shaft dia = 13.5 mm
[750 is about 15 mm, if I remeber well]

hope that helps

Daniel

[Leonardovans]

Does this mean I have the 750 advancer?

[Herr Supersport]

Don't know - mine was 100% shure the original one - nobody wrenched on the bike before it was mine.

What I know is, that I got an electronic ignition equippment designed for 750 that didn' fit - the centerhole was as mentioned 15mm.

If you like, i can post a picture some time later - im sitting in the train now - advancers are marked with numbers, that show to which bike they belong.

[Leonardovans]

Please do if it's not too much trouble.

[Leonardovans]

Also, I saw the little line on the shaft. What does it mean and is it in the correct place? What does it line up too?
I ask because the bike has been worked on by PO.

[Herr Supersport]

So - finally at home/finito lavoro.

The CB400f advancer is stamped "333".
I think any advancer of a SOHC4 Honda can be used. Hondaman postet [as usual] some very interesting thoughts to that subject - please use the search-function.

As I had in mind, the diameter of the shaft is 13.5mm - see pic.
The mark shows the correct position of the excenter-piece ["OK or 180° inverted"]. Cannot remeber what position fits, you find the description in the shop manual.

[Leonardovans]

I see. But my shaft measures 15mm and the plate is stamped 333.

[Bootsey]

Check out this thread - Post #36

http://forums.sohc4.net/index.php/topic,34454.25.html

[Leonardovans]

Rufus from 4into1 says I need the Dyna S DS1-2 for the CB500 CB550 & CB750 because I have the 15mm shaft. Weird.

[Leonardovans]

On another note, I started stripping and cleaning the carbs.

I wanted to remove the air screws and then noticed the are different to the other 400Four carbs I have. The ones on these carbs are plastic and I don't think they can be removed.

Any ideas guys?

This is a pic of the ones I am cleaning.



This is a pic of the ones on the bike I am trying to get running.

[01Thomas]

That plastic air screw is in fact just a pre-historic emissions control device. The tab on one side of the plastic bumps against that aluminium casting (seen in your 2nd photo in the eleven o'clock position). It prevents one from giving the screw a full rotation and was intended to discourage tampering.
The plastic is just a cap that is pressed over the actual brass screw. The sides of the brass screw are splined to give the plastic cap some grip. The plastic cap can easily be prised off and then you will have what's in your 2nd photo.

[Leonardovans]

Thanks 01Thomas.

Now I have to take them out and run the carb bodies through the ultrasonic again.

[marting100]

Hi Leonardo.
I did get the same issue with the larger shaft thing for the cb400F Dyna S.
It's normal as per Larry from Dynatek (great guy and customer service, 2 days later and the larger shaft was at my house)
Contact him!!! (see below)
M

"The majority of 350/400 motors will use the rotor included in the DS1-1 kit.
However, a small number of these machines used a mechanical advance assembly
that has a slightly larger shaft size. In these cases, we include a note in
the kit advising the installer to contact us so the larger rotor can be
supplied at no charge.
Please forward your full name, address and telephone number and we will ship
you the correct rotor at no charge.
Thank you,
Larry Nelson
Technical Support
Dynatek
1-800-928-DYNA (3962)
http://www.dynaonline.com