Chasing missfire

[Z1B Alan]

got a z1b with electronic ignition had a missfire on no2 cylinder
swaped with no1 plug and so did missfire.replaced with new plug ,however then no3 was not firing so i swapped with no4 and so missfire shifted also,is it possible the plugs are faulty or would you susspect the electronic ignition.
plugs are NGK B8ES Have heard they are not good
any ideas would be welcome.
what are the correct nippon denso {part number}

[london calling]

DENSO W24ES-U.

The NGK plugs seem to foul up quite easily and once they have they seem to be finished.
I've been using DENSO since reading a thread on here a couple of years back and wouldn't use anything else now. :

[Jeff Saunders]

I would disagree about the Denso plugs. IF the bike is running correctly, the NGK B8ES plugs are perfect - other plugs like Denso are not as good - although they are a close equivilent.

You can check a lot of different things to help determine problems...

1) put fresh, correctly gapped spark plugs in the bike - do not change heat range unless you have a reason to do so (like higher compression pistons).
2) make sure the ignition timing is set correctly on both 1+4 & 2+3.
3) make sure the coils are still good - if you are running the original coils that is probably part of the problem. You can perform a resistance check on the coils, but that will not tell you if the coils are good, just if they are bad. It is still worth checking resistance. You should get a reading of 3.5-4.2 ohm on the primary side, and 15k-20k on the secondary side - they key is the reading for both coils should be darned close.
4) if you are running the original coils, the wires typically degrade over time - sometimes you can help a little by chopping 1/4" off the plug wires to assist the plug caps in gettng a good contact. Reality - you need to get some better coils with replaceable plug wires.
5) if you are running the stock, original plug caps, these too fail with age.
6) check the voltage at the battery and then at the coils - you will always see a small voltage drop - but if you lose a full volt or more, you need to check all the connections in the wiring - often old ignition switches, poor connections in the kill switch and all the different connectors degrade the voltage.

There are many other reason you can get a misfire too - poor valve clearance, air leaks, sticky igntion advancers, partially clogged carbs, worn carbs, poorly jetted carbs, weak battery, undercharging stator or a regulator that has started to fail.

[Pigford]

Z1B Alan, sounds like could be a duff coil, as trouble is with same one (ie: # 2 & 3 plugs).
Try swapping coil supply to see if problem shifts to # 1 & 4!? As jeff says, a 30 yr old set of coils is not great for any bike..... They always were only just about OK when new... Treat yerself for Xmas. :laugh:

[chrisNI]

I would disagree about the Denso plugs. IF the bike is running correctly, the NGK B8ES plugs are perfect - other plugs like Denso are not as good - although they are a close equivilent.

Jeff you must get different NGKs in the US than we do or the weather may have something to do with it - if it's drier maybe they start easier? I got fed up throwing NGKs out the Denso's have been totally trouble free. All this with Dyna 'S'

[Jeff Saunders]

A lot has to do with how the bike runs. As the engines and carbs age, they tend to run richer. It's the combination of needle / needle jet wear, the cam chain wear impacting cam timing, lower compression and much more.

I found the ND plugs to run too hot in most engines - to me, they seem to be between a B7ES and a B8ES.

[london calling]

I had the same trouble Chris with the NGK plugs.In fact i think it was one of your threads i read reccomending DENSO.
Jeff made many good points about the ageing process on the electrical and ignition systems.It's all about being thorough and systematic when checking things out,there are no short cuts.A cool head,proper test gear and a fat wallet are a big help. :

[paul doran]

I have to say i agree with Jack and Chris
experience has found ngk are total crap
I now only use nippon denso and have no problem's
but everyone to their own

[davejames]

Yep I'm another, have gone through 3 sets of NGKs in one summer. Once they're fouled there fu**ed end of story. Agree with Jeff though I suspect it's down to worn carbs and ignition etc. One of my coils is a Su**ki one held together with insulating tape as I found out last year when the tank came off

[Z1B Alan]

changed plugs again now running on all four, possibly just a couple of dudd plugs? where can i buy the nippons somwhere near chester would be nice or maybe mailorder?

[london calling]

Denso U.K. are based at Coventry and if you visit their website you should be able to contact them for your nearest stockists in your area. :

[chrisNI]

sparkplugs.co.uk are fairly cheap.

[Pigford]

Sorry, but I use NGK with no problems! B8ES in me Z1000 (1075, Dyna set up & RS36's), have done in all of em with no hassle! Pot luck maybe? :O

[ROZZER]

:cool: ?8.88 for 4 plugs delivered to your door Our Kid! from Sparkplugs.co.uk
Get yer hand in yer pocket yer tight wad! :p

[hanskloss]

I had NGK B8ES on my Z900, runned sweet but the plugs were constantly black, tried hotter B7ES which helped a bit with the colour round the tip, now running on Splitfires and they're fine + have psychological effect of split electrodes wow! :p , also got a set of Densos from ebay for ?5 delivered just because it was cheap :p and will use them in the future, any plugs I used performed fine with no problems, just the black colour that looks like fouling but doesn't actually get that far, it was discussed earlier on the old site that possible cause is modern fuels