By hondapaul
Hi All
just bought, and fitted, the iridium "8" plug as sold by Hitchcocks and the bike is running not quite the same...
Checked the original plug and it is simply marked "Bosch R6" - looked up all the plug comparison charts and "R6" is noyt listed.
Just wanted to check that fitted an "8" plug and not "7" as mentioned on other Himalayan sites as am a long time rider (read - old fart) and do know that the wrong heat grade of plug is not good.
Any of you had trouble after changing the plug - was yours and R6 or other.
i have indexed the plug and it is sitting corectly
forgot to add my enfield is a Himalayan 2018
User avatar
By Presto
Can you say how the engine with the NGK plug is running 'not quite the same'? Unless you're running to some extreme - of very high speed or very short slow trips - I can't see how there could be any identifiable difference in the way the engine runs with this iridium plug.

Any chance this difference is psychological?
By hondapaul
Been riding for far to many years and always did seem to notice thing others did not
Bike was instantly more vibey and took longer to warm up... it never stalled with the std plug but 1/4 mile to my first junction it stalled.
Runs great once warm but not so much while getting there
User avatar
By Leon Novello
I note that you have been riding for many years, but the instructions on iridiums say tonot alter/adjust the gap. If you have altered the gap to your usual setting for the old plugs, you might have damaged the electrode.
Just a thought. :?
User avatar
By Presto
I am skeptical about any of these ‘issues’ (vibrations etc.) being due to the spark plug. It makes no technical sense that it runs well hot but not before then. If the plug was too hard it’d work well until fouled up but that would usually take a few miles. If it was too soft then it wouldn’t run well when hot. If you’d damaged the electrodes by adjusting the plug gap it’s unlikely to run well at all: cold, warm or hot.

By the way it is not correct to say that NGK iridium plug gaps cannot be adjusted. The NGK instruction is that they can be adjusted but with care that altering the angle of the side electrode does not damage the brittle and thin central electrode.

I quote NGK’s advice:

“A variety of techniques are used to adjust electrode gaps. An appropriate method and tool should be used for gap adjustment although it has come to our attention that a variety of improper methods are used that lead to implications.
When adjusting the electrode gap, the gap may commonly be made too small, as such, the gap may need to be opened slightly. Typically some customers use a lever such as a flat screwdriver to pry open the gap. Traditional Nickel plugs have a solid piece Ø2.5mm centre electrode that may withstand such force. Precious metal spark plugs however have Ø0.6mm fine tips that are laser welded to the centre electrode. These tips are very fragile and not designed to withstand any force. As such NGK will not provide warranty for the breakage of precious metal centre electrode tips.
It is possible to adjust the electrode gap on precious metal spark plugs using an appropriate method that will not place any force on the centre electrode tip.”
User avatar
By Leon Novello
Hi Presto: Instructions have changed over time; I fitted my Iridium plug around 2006, it cost $22 AU. It was in the bike for about 30000 kms. The instructions on the box said the gap was pre-set and do not to attempt to alter it.
User avatar
By Presto
You're right Leon. NGK advice does evolve over time.

This is the case with resistor plugs and plug caps. The advice used to be ‘either/or’ not ‘both/and’.

That has now changed and NGK advise the use of resistor plug caps with resistor plugs. They give a number of reasons – the main one to reduce ‘radio’ interference to legal levels. They also stress that their present range of plug caps will eliminate the detrimental effects of any loss of current resulting from two resistors.

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