NGK Plug Problem

[Hedgehog]

Decided to try a new set of standard NGK plugs before finally committing to the expense of Iridium's as part of my annual service...

Duly fitted a set of 6 dirt-cheap DPR7EA-9, gapped to about 33 thou...

Fired her up..

Bike started, but had intermittent backfire and generally rough running..didn;'t want to idle at low revs at all.

Out came the new standard plugs and opened the gap up a little - tried again. Same.

Back in went the old Iridium's that were in there in the first place.

Perfect... back to normal.

Now why would I get that on standard plugs..?

Any ideas? ??? ???

Thanks

HH

[Bone]

Don't forget she's a Lady. Get her used to the high priced things and cheap won't due !

Can't answer your question.

[salty1]

BOY, can't think of anything other than one or more of new plugs is at fault. I think your replacement with the iridium plugs again bears this out. Re-install the new std plugs and try removing one plug wire at a time to see if you can isolate the bad one. Real curious what you find.   

[wild6]

You may have another problem (bad wires, resistors) that the iridium plugs have be masking, but surfaces when a plug that needs a little more oomph is used.

[Patrick]

My thought is you have one or more defective plugs,, maybe they have been dropped, damaged when adjusting, or some such thing..

[gordonv]

Ah, first problem, you stated iridums as part of your annual maintenance. What? They are good for 100K miles, why would you change a $7+ part that should last almost a life time, annually?

Maybe do some searches on plugs. It's been hashed out a lot. Unless you can trace a problem to a bad plug, I wouldn't even change them.

I bought iridium also, but for long life, no maintenance.

Sounds more like your problem might be that the leads are not plugged all the way onto the spark plugs. Maybe fit the plugs into the boots when before you install them into the heads, to see how they are held.

[wiggydotcom]

Here's a stretch, but just want to make sure you aren't missing anything. Did you remember to remove the screw-on top of the new plugs? The Valk plug wires fit on to the threaded top of the electrode. The screw-on tops get tossed.

[FryeVRCCDS0067]

I've bought plugs a time or two over the years and had one or more be defective. Probably a good chance that's what happened here too.

[Hedgehog]

HI,

Many thanks everyone for your helpful advice.

The plugs came without the screw on bits - so that was OK. and I don't replace plugs every year its just a new bike to me this first year, so I'm being extra careful (and indulgent).

Generally I have to agree that its probably either defective plugs (all 6 went back to the store today) or perhaps the better conducting iridium's masking another low -output type problem somewhere else.

I did notice that the iridium plugs had a a very sharp point on the electrode... don't know if that means anything. I also sprayed the caps with WD 40 and put a tiny smear of copper grease on the threads of the standard NGK's, but neither of these things should result in a problem.

Anyway - I'll be sticking new Iridium's in next week and see what happens then...

Most odd.

[Rio Wil]

I don't know why anyone would replace the stock plugs with anything else other than feel guilty at about 100K miles and treat the old gal with something new.  The plug in the pic has 100K miles and it made absolutely no difference in idle or off idle running at any speed or acceleration when I put new NGK's (from a auto parts store) in.  Kind of like the timing belts,
feel good item at 100K.

[Hedgehog]

I don't know why anyone would replace the stock plugs with anything else other than feel guilty at about 100K miles and treat the old gal with something new.  The plug in the pic has 100K miles and it made absolutely no difference in idle or off idle running at any speed or acceleration when I put new NGK's (from a auto parts store) in.  Kind of like the timing belts,
feel good item at 100K.


Why? because its my pleasure to do so.... Its a new bike to me and I can afford to pamper her...

Besides - I like getting to know the bike by tinkering..

In any case, in this instance there clearly is a difference between standard NGK's and Iridium's - for whatever reason..

[salty1]

The iridium plug has an electrode that comes to a sharp point, they are built that way.

[Rio Wil]

Why? 2funny 2funny 2funny because its my pleasure to do so.... Its a new bike to me and I can afford to pamper her...


Chuckle....I can appreciate that and the old gal makes out. It will be interesting to see how this shakes out, this bike seems to be real easy on plugs and not a bit finicky. The point being, I don't think this engine cares between a NGK and a high dollar plug, if there is a difference it would suggest a bad plug or  loose connections of some sort upon installation.

[Hedgehog]

I think you may be right Rio - an under performance somewhere else in the system... unless this batch of NGK's was faulty of course... But for now I'll do what works and replace with Iridium's then check through the rest of the system...

I'm a fool for this bike, just like some men are for some women. Can't help myself. I'm addicted..
 

[Rio Wil]

I know what you mean about this bike.  I left the house this morning  just before daylight, about 46 degrees and clear.  Headed down to San Jose to a electronics swap meet see if I could score a couple of 400-500G SATA drives for my garage PC.  Been riding for 15-20 minutes watching the sun rise and realized my face was hurting.....first thought it was the cold, then realized it was from a big friggin grin....just enjoying the cold, the sunrise and the phat lady, she runs really good in the cold air.  What a bike!!

[Hedgehog]

Yes Rio, its something special.

I had a similar ride this week - cool air in my face, sunshine and smell of fresh cut grass (the legal kind)  and this lovely snorting beast of a bike burbling away. Somehow the seating position makes you feel like king of the world on a morning like that.

Guess that's why I spoil her. She's worth it!


Hedgehog

[RP#62]

Its just the opposite of road rage.  Its called road joy.  Had it happen to me the other day - almost had to wave somebody over to see if they needed a hug.

-RP

[Hedgehog]

Yup, I get that all the time RP!

'Road Joy'  - Like it.