Spark Plug HT Leads

As part of a general machine update I am considering new HT leads and eventually a single coil.

I see entries about HT leads that are suppressed. What is the difference and impact when using HT leads that are suppredded?

TT,
I'll jump in here with what I know or suspect.
Suppressed refers to noise suppression, the "noise" being electrical interference with your car's electronics and radio. This should not be an issue with your Norton. I have tried to repair a suppressed lead on the road and found what, I suspect, is a fiber lead inpregnated with graphite or carbon. I may be all wet on this.
Since our ignition systems are marginal I try to avoid using anything that can compromise it further.
If you order from a knowledgable Norton supplier you will probably be better off. You will get leads the right length, right size, and factory connections.
Skip

I bought a roll of Packard 440 cable some years back. Solid copper core, black outer cover. It's pretty easy to make up your own leads. If you are running a Boyer microdigital ignition or a Sparx electronic regulator you will need to use resistor spark plug caps (NGK) or run resistor plugs. Otherwise you can find new Champion caps from many Norton dealers.

A lot of the pre-made leads are made from carbon impregnated fiber.

I believe the suppression requirements are not for the benefit of the vehicle operator but to prevent interference with radios, televisions and other electrical appliances in the immediate vicinity of the machine.

dave M said:

I believe the suppression requirements are not for the benefit of the vehicle operator but to prevent interference with radios, televisions and other electrical appliances in the immediate vicinity of the machine.

Click to expand...

That is certainly correct, and was (I guess still is?) a legal requirement in the UK, there being a suppression sticker fixed to the bike (late models) when new showing that it conformed to the standard.

However some modern bike electronic systems can also be affected by an un-suppressed ignition system, like the Sparx high output electronic voltage control boxes, the manufacturer reccomending that suppressed plug caps are used (or suppressed plugs?) or overcharging can occur.

Boyer Bransden Micro-Power and Micro-Digital ignition units also need ignition suppression to work correctly. Boyers also reccomending that copper core HT wires and not resistor (carbon) wires be used.

Thanks for the input.

I have a Boyer on my 850 MK II but I am unsure of the HT leads, plug caps and sparkplugs with regsrds to being suppressed or unsuppressed.

There is certainly nothing on the caps to indicate to indicate what they are.

They current HT leads are black outer with a copper core. I need to research thet status of my NGK Iridium sparkplugs .

TT said:

I need to research thet status of my NGK Iridium sparkplugs .

Click to expand...

NGK plugs normally have an 'R' before the heatrange number to denote that a plug is resistor type.
NGK (red type common in UK) caps are normally marked if they are resistor type = 5K (and the Ohms symbol) along with the cap model type.
NGK code info: http://www.spark-plugs.co.uk/pages/tech ... l_code.htm

You would obviously only need to fit either one or the other (suppressed plugs OR caps). A healthy ignition system should be able to cope with doubled up suppression but not really recommended.

The Boyer analogue 'black box' MkIII type ignitions function quite happily with no suppression.