Denso spark plug probs

[Robw]

Hi, I got a set of new plugs which I have fitted to my new engine. After a few times of starting it up, it failed to run. I checked the plugs and only a couple are sparking, when I fit an old NGK B8ES off my LC, I get a lovely spark.
Apart from changing the plugs anybody got ideas why the plugs failed so early.

Cheers Rob

[Reecy]

Rob,

I have had various disappointments with plugs NGK were crap, Denso were much better but really i put it down to an old electrcial system struglling to supply the current.

I was steered to try the NGK iridium pplugs and gave it a go--they are really good, i dont know about life span but so far they have given my Z1000A2 and my Z1R some extra go and some easy starting.

To quote Loz (ita1 on the ownersclub) they would set fire ot a bucket if piss---they do exactly that.

Try them --they cost a about £7 or £8 from Halfords or better still are sheaper from www.sparkplugs.co.uk

Reecy

[Robw]

Reecy, thanks for the info. Sorry should have made it clearer, the old plugs where Denso. I have now fitted a set of NGK B8ES and it starts fine. I will wait and see if the engine eats these plugs after a couple of starts.
I will check my Halfords to see if they have some in stock.
Cheers Rob

[Big John]

Strange, I've got NGK's in my 350LC and have never been a problem but have had problems with NGK's in some of my Zeds, fitting Densos seemed to cure it.

[Phil50]

Bought Denso, 2 failed withina month. Went back to NGK that worked ok for the last 30 years. If NGK were not good they would soon be out of business.

[steve bowdler]

I run NGK s on my z1000 no problem what so ever

[DogsbolloxofZ1B]

I bought 3 sets of Denso plugs off the back of an article on this site and had no end of troubles, refitted B8ES and hey ho its perfect. Maybe I had a bad batch but I think I'll stick with the originals.

[AL MARSHALL]

i put denso plugs in my wifes z 650 and they caused no end of trouble. re fitted used ngk plugs and it ran fine. these were brand new denso straight out of the box. think i will try iridium plugs next time

[Al]

Put four denso's in my rebuilt engine last month and it missfired and spluttered and coughed and after replacing everything in the ignition system believing the new plugs must be OK, it turned out that two of the four were duff.
Not at all happy about that, but put the 3 year old NGK's back in and it ran perfectly.
FYI; the two that failed showed up as discoloured between the ceramic insulator and the steel body with a ring of brownish sticky off coloured seepage.

50% failure rate=un-acceptable in my experience.
Bought these back in January if it helps. Maybe a bad batch as someone said.


AL

[Robw]

I had a chat with Steve who works at my local bike shop (Orwells), he said that they always changed Denso plugs for NGK when they sold new bikes. Curious how people have had different experiences with these plugs, so I suppose it is down to poor quality control.

Cheers Rob

[bedlow1]

never needed to try Denso as NGK work well in all my Zeds

[Pigford]

Interesting how a few comments can turn it Full Circle...

I am running the Trumpet ready for its MOT Sat morning..... and it kept fouling plugs......

Had NGK in it (B8ES), so whipped a couple of Denso's out of the Lawson.... but one still oiled up

Bunged some old NGK's back in & Hunky Dory

Might get some Lodge or Champion

[mick znone]

had ngk, no problems, heard denso's were great, have them in now with no problems, so im no help there then

[steve bowdler]

Use what ever your bike tells you (its like having another wife)

[floydsz1]

I have denso's in me z1a. After i rebuilt the engine it sometimes would only fire up on 3 when cold but if i pulled the plug cap away from the plug slightly it would fire up ok. After about 30 secs it would run ok when it was put back on. This happen quite a few times but once it had done about 300 miles it all seems fine now.
Done about 1000mls in total since rebuild and still all ok.