spark plugs

[ogre]

well i am confused now.had loads of trouble with ngk,s goin back a few years so turned to denso,s recently .rebuilt my z1a recently only just had chance to run it on the road to test it.bit lumpy tick over bit of lack of power on first run but seem to dial itself in a bit.but then lack of power.checked it not much fuel in bowls of carbs 1+2. i know i took a risk with the t pieces bodged them with o rings i m/c them but the rubber at the end had come off and blocked the hole.so thought sod it i will change the inlet manifolds for new ones at same time.so finally got round to testing again.total lack of power but it was hunting and revvin up and down a bit at tickover .so slept on it got round to pullin it out again.i thought this is sparking issues and cudnt believe it turned out to be a faulty new denso plug after only bout 80 miles found an old ngk in the garage and different animal.tricky one really cos it was sparking but obviously not properly.so dunno which way to go now.

[zed1015]

Have never had any trouble with NGK's or the Denso iridiums.
I've had the same set of NGK's in my Z1R for 15 years or more and only recently changed them as part of a good going over for a 2000 mile round trip to Portugal but the new ones made no difference.
I've got 8 Denso's in the twin plugged Drouin and NGKs in the alloy café and both have the same sets in since built 10 and 5 years ago respectively.
A lot of folks go on about fake NGK's but they are easily spotted as they don't have the four digit number on one of the hex flats and a few other subtle differences that are highlighted on the NGK web site.
Most plug trouble is down to other areas like over fueling or oiling caused by worn rings and guides and no amount of plug changes will cure that.

[ZedHead]

I have read a lot of comments about NGK and decided to contact their technical department about it.

The conclusion I have reached is there is nothing wrong with NGK, I is just that Denso equivalents have a slightly different heat range which tends to work better in old engines running modern fuels.

Ethanol fuels run cooler and our riding styles have changed a lot over 40 odd years, since KHI first selected B8ES plugs for zeds. The recommendation for classic engines is go one range hotter to B7ES.

You can download an extract from NGK research from my website.

https://www.cybike.co.uk/Downloads

[chrisNI]

You can download an extract from NGK research from my website.

https://www.cybike.co.uk/Downloads

Useful - thanks

[Kev1R]

I can only echo zed1015's comments

I have always used NGK's & never had a spark plug issue

My current Z1r I bought in 1980, and also used NGK in several bikes before that.
The only issue with iridium plugs is they seem a bit pricey - and I am yet to be convinced they offer anything extra for 1970's bikes.