Thought I better split this subject off from the bike thread.
It seems that the ignition advance on the 5H4 motor is not compatible with the TCI unit of the bike.
I can see how a mechanical advance will work and it can be shown in these diagrams.
The mechanism on the left will slot into the mechanism on the right and as the centrifugal force pushes the weights out the slotted part will advance the spark by turning the base plate (which the vacuum advance also interacts with)
It has been said that the 5H4 motor does not need the mechanism pictured on the left as it has a 4RO TCI unit that takes care of the ignition advance.
After reading the manuals including the supplementary additions for the later no adjustable ignition timing. I can see no reference or even parts catalogue of this ignition advance system?
Here you can see the 5H4 setup complete less the screws mounting it to the motor(Edit, sorry it does have the mounting screws on). Notice the large key way on the shaft and on the base plate. I can't see how the base plate can be moved to advance the spark with this setup, It is said that the TCI unit does this but I don't understand how it can> I also don't understand why it has key ways if they will not be used?
An exploded view
The mechanical ignition advance unit installed (although it is missing the key part that is meant to move the base plate. The manual calls it a reluctor. I figure I can get one of these and then this system might work but I would have to also replace the base plate with one that has the smaller key way or make this base plates key way smaller.
Here is the TCI unit on my bike for reference as well.
