KH500 positioning of magneto points.

[jj.palmer]

Hi,
KH500 fitted with Lucas K2F magneto.

I am wanting to position the magneto points relative to the correct cylinder that is being timed. The Ariel owners guide states that you position the "segment" opposite the HT pickup for that particular cylinder that is being timed but I am unsure what is meant by "segment", do they mean the "cam follower" ?

For clarification, see photos :
At "A", with points just opening, is it the "right hand" HT pickup that is being activated ie the segment or cam follower is opposite the HT pickup.
and
At "B", with points just opening, is it the "left hand HT pickup that is being activated ie similar to above.

Your help would much be appreciated, thank you.

Regards,
John P.

[pete.collings]

The segment referred to is on the slipring, a brass section that will transfer the spark to the pickup. Remove the pickups, and use a small mirror (eg. dental mirror) on a stick (if the magneto is on the bike) to see which side the segment is, and replace the ht lead on that side to the cylinder being used to set the timing (ie, where both valves are closed on the compression stroke).
There is often a slight varation in the timing between cylinders, so once the timimg is set on the one side, check the position of the piston (or timing disc if used) to see what the difference is. It may be necessary to "share" the difference in timing (ie. one cylinder slightly advanced, the other slightly retarded).
Be aware that there are two different types of slipring for a K2F magneto, dependent on the rotation of the magneto. A KH should be anticlockwise, if a clockwise slipring is fitted there will be no spark! You should be able to see the brass section in the pickup hole as the points open.

[jj.palmer]

Thank you Peter for that info., I can now see the segment through the HT pickup holes in the mag. it now all makes sense.
Whilst I have the attention of an expert would you please confirm whether or not I have assembled the insulating washers correctly within the contact breaker assembly, see attached diagram.

Thank you again, regards,
John P.

[pete.collings]

Although I am more familiar with the early brass contact breaker assembly, I think from your diagram that what you show in your diagram is correct. In essence, the inner core of the armature is linked through the centre screw, and insulated from the main body of the points block which is connected to the outer earth part of the armature. The earlier brass block also had an carbon earth brush to connect to the body of the magneto itself, although if this brush is missing, the magneto can still work.
To be sure of the insulation of the points block, remove the block from the magneto and just connect a multitest meter set to resistance reading across the centre screw contact point and the main body of the block. Pressing the points open and closed should show the level of resistance present. Although I don't have any values for the resistance, I would expect it to be fairly high.
Hope this helps, I don't profess to be an expert although I have rebuild quite a few magnetos, if anyone else can add to what I have said please do so.

[jj.palmer]

Peter, thank you again for your help and advice, you can never stop learning.

Regards,
John P.