Spark plug leads.

[Fat Dell]

Hi everyone.
Can someone please confirm if it matters what cylinder the leads go to that come from the mag. Cheers

[Fat Dell]

Sorry, that’s on my 1961 A10 Super rocker. Thanks

[chaterlea25]

Hi Dell,
Yes it does, the engine will not run if they are wrong

John

[berger]

yes but if it doesn't start swap them over

[Fat Dell]

Thanks guys.
The lead I’ve got circled in red is currently running to the left cylinder (left when sitting on bike). Are you able to confirm this is correct? Thanks again.

[Black Sheep]

See the above answers. It really doesn't matter as long as the spark is going to the correct cylinder.

[groily]

Just depends on the preference of he who last set the ignition timing, as per previous replies.

If it helps you, a key thing to know is that when the points are opened by the lower cam on the camring - fibre heel at about 4 or 5 o'clock -  the lead attached to the gearbox side of the magneto sparks. And when the points open on the upper lobe, at 10 or 11 o'clock-ish, the engine side lead sparks.

To check which way yours is set up, turn the engine till the points are just opening on one or other lobe of the camring, and see which piston is on the compression stroke (ie both valves shut). Attach whichever HT lead is ready to fire to that side.  The other side will be on the exhaust stroke and you may be able to see if its exhaust valve is open by aiming a torch down the plug 'ole.

If it's been set right but won't go, swapping leads will sort it, as everyone says.

[Swarfcut]

 As a further note of explanation the magneto has two cam lobes, one set of points, and a  HT carrying slip ring to the pick ups which does not have a continuous conductor. The trick is to remove a pick up and rotate the magneto until the  slip ring brass segment comes into view as the points open. This plug lead goes to the cylinder which is on compression and ready to fire.

 So to echo Mr G et al, he who did it last time is how you will find it. Now whether it was actually timed up correctly is a different matter if it still won't go.

 Swarfy.