Life span of a spark plug?

[Snaggletooth]

Ok, I'm wondering.......

 

I used the NKG DPR8EA plugs for a couple years and wasn't happy with the life span. I changed to the NKG DP8EA plugs a year or so ago. Not much difference in how long they last.

 

I run them at .035 gap and they are consistant with a nice tan burn on all of them. No fouling and gaps are barely off spec. I can clean and regap them and not get a lot of improvement.

 

It's the same story every time. The bike starts and runs great for about 4,500 to 5,000 miles and all of a sudden it gets picky about starting. I mean real picky. Down right bitter about starting. It will always start, but it's a stand off for a while.

 

A quick change of plugs and she's back to touch of the button. Same way every time.

 

I expect more life from a plug than that but I can not find a reason for the the plugs failing at such a regular schedule. None of the obvious stuff anyway.

 

Caps and wires were new two years ago and still test like new. No corrosion, no resistance issues.

 

The battery isn't the problem either. It's full charge and as soon I change the plugs she's like new again.

 

Any suggestions?

 

Mike

[Flyinfool]

Convert to diesel??????

 

No more spark plugs.

 

 

 

 

 

Sorry, couldn't help myself.......

[Snaggletooth]

Oh ... a wiseguy uh?

[dingy]

It has been my experience that as a general rule a spark plugs life is from when you put it in till when you are sure it is the source of whatever ails the motor & you decide to change them, good, bad, or just dirty.

 

My dad had a sand blaster that was made just for spark plugs and the were like a cat, nine lives. He was a pro dirt track racer, and he led about half the Daytona Beach race in his Triumph Elite class in 1949, so I think he may have known a thing or two.

 

Try gapping them a little tighter on the next set, like .032" and see what it does. Shorter arc may not erode plug as badly.

 

Gary

Edited August 16, 2011 by dingy

[Black Owl]

But remember

The shorter the arc

The colder the spark

[1 Canuck]

Just a thought, there is a ceramic insulator around the electrode of the plug. There can be carbon tracking of the voltage/spark from the electrode down the ceramic insulation to the ground, away from the gap.

As you know the spark will travel with the path of less resistance. I have also seen very, very fine cracks along this ceramic insulator as well.

Spark plugs have also been known for shorting/arcing within the plug itself (core) to ground.

My guess would be use a cross chart and try a different make of plug.

 

[Condor]

I usually toss a new set of plugs in every year in the spring. They're cheap enough so it's not that big of a deal...

[Snaggletooth]

I usually toss a new set of plugs in every year in the spring. They're cheap enough so it's not that big of a deal...

 

Well, yeah that's SOP for me. But I just put in my 3rd set for the season.

 

Been riding a bit more this year.

[dray]

I used to have the same problem when I had my 1100 Vstar; every time it would hit around 2500 to 3000 mi. it would start hard, drop as much as 10 mpg or more, stumble on take off even when warm,

if anyone goes to the 1100 riders fourm you will find this is very common with them

 

I still have 5 or 6 sets of plugs for it I never left the house without a set or two; as i have purchased new one's that one of the two would be bad

 

and i never buy wal mart or k mart plugs Ill go to a auto parts or dealer and pay a little more for them

 

Dray

[dray]

Well, yeah that's SOP for me. But I just put in my 3rd set for the season.

 

Been riding a bit more this year.

 

if your mpg is dropping like mine did you should be getting the cost of the plugs back by the time you put your 3rd. tank of gas in

 

at the cost of gas and figuring plugs at around 2bucks each even at 3 bucks is only 12 thats less than 4 gal. of gas

 

so with adding in mpg; the plugs are free!!! WOW! what a deal eh!

now see you can buy saftey chrome with the you save:big-grin-emoticon:

 

 

Dray

[Ndiaz]

I replace my set of NGK's once a year in late Fall, by force of habit. I ride about 10,000 miles a year. No plug-related problems so far.

 

Nick Diaz

Middletown, MD

[Handyman]

Usually when a situation repeats it's self, there is a reason. Spark plugs aren't that complicated. Normally they work or don't. I don't think wearing them out tri monthly would be normal. I also don't think you would be unlucky enough to get a bad batch every time, even if there is an occasionlly bad plug sold. I think I would look elsewhere. Bad or old wires or caps could shorten the plugs life span. Maybe even weak voltage. Just my opinion.

I hate these kinds of problems, I had rather my bike just quit so I can fix it and get back to enjoying the ride.

 

Richard

[RSTDdog]

As you suggested your self, try switching brands. If you can find them, try Nippon Denso Plugs. Most Aisian car mfrs will spec NGK and NIppon Denso numbers in the Owners Manual. My Mazda Miata specs either of these. I think Toyota and Hyundai do as well. I'm 9000 miles in on NGKs on my RSTD and seem to be OK still, Starts and Runs fine, I know Yamaha Specs changing them at 8000 in the OM on the 2nd Gen IIRC.

 

If I read it correctly, even if you clean them well and re gap, its still a hard start until you get brand new ones?

 

Switching brands seems easiest thing to try first, Let us know how you make out on your plug test.

 

RSTDdog

[Gearhead]

Mike,

 

I don't really know, but it's not normal in my experience. I have the NGK's in the Venture and I run many thousands of miles on a set. In fact, I've put 50k on my 87 VR (bought with 45k, now have 95k) and I think I've only replaced them once. And when I did, it ran the same.

 

I've put almost 100k on my 87 Virago. Ran NGK's sometimes, Champions sometimes. Never made a difference to running, starting, or MPG, and I track MPG for every tank. The only thing that consistently affects that is the attitude of my right wrist...

 

So when you pull them, they look good, right? Tan, still sharp edges on the electrodes? Yet there's a dramatic change in the starting. Weird. Does it affect other aspects of the way the engine runs - smoothness, power, MPG? The only thing I'd change, as someone suggested, is run the gap at .030-.032. If I'm not mistaken, the spec is .028-.032.

 

Jeremy

[Ozlander]

Mike,

 

I don't really know, but it's not normal in my experience. I have the NGK's in the Venture and I run many thousands of miles on a set. In fact, I've put 50k on my 87 VR (bought with 45k, now have 95k) and I think I've only replaced them once. And when I did, it ran the same.

 

Jeremy

 

I agree. Last time I remember changing plugs was in 2001 before going to Alaska.

(However, replacing known good plugs with unknown new plugs might not be a good idea)

I replaced them this year when I adjusted the valves as I had them out anyway.

[dingy]

The only thing I'd change, as someone suggested, is run the gap at .030-.032. If I'm not mistaken, the spec is .028-.032.

 

Jeremy

 

Just checked the 83-85 service manual. Same in 86-93 service manual.

 

Specification is for gap of 0.8 ~ 0.9mm (0.031" ~ 0.035")

 

Plug type DPR8EA-9/NGK, X24EPR-U9/Nippondenso

 

Gary

[BradT]

I don't think wearing them out tri monthly would be normal.

 

I think I would look elsewhere. Bad or old wires or caps could shorten the plugs life span. Maybe even weak voltage. Just my opinion.

 

I hate these kinds of problems, I had rather my bike just quit so I can fix it and get back to enjoying the ride.

 

Richard

 

Agree completely expecially the last paragraph

 

Brad

[bobcat]

About 5 years ago I was having a similiar problem with plugs except mine were giving me problems at about 5-6000 mi..Someone on this forum suggested using non resistor NGK plugs...Been fine ever since..Now I change them every winter just for GP at about 10-12K..

[Snaggletooth]

Usually when a situation repeats it's self, there is a reason. Spark plugs aren't that complicated. Normally they work or don't. I don't think wearing them out tri monthly would be normal. I also don't think you would be unlucky enough to get a bad batch every time, even if there is an occasionlly bad plug sold. I think I would look elsewhere. Bad or old wires or caps could shorten the plugs life span. Maybe even weak voltage. Just my opinion.

I hate these kinds of problems, I had rather my bike just quit so I can fix it and get back to enjoying the ride.

 

Richard

 

Plugs have been purchased from several different suppliers over the years so the odds of a bad run are slim. Like I said the wires and caps are within a couple of years old and test like new. The plug wires are also shielded with protective sleeves to avoid wear problems. The plugs each fire well out of the heads and the wires when tested with an adjustable spark tester jumped a gap of 5mm.

 

 

As you suggested your self, try switching brands. If you can find them, try Nippon Denso Plugs. Most Aisian car mfrs will spec NGK and NIppon Denso numbers in the Owners Manual. My Mazda Miata specs either of these. I think Toyota and Hyundai do as well. I'm 9000 miles in on NGKs on my RSTD and seem to be OK still, Starts and Runs fine, I know Yamaha Specs changing them at 8000 in the OM on the 2nd Gen IIRC.

 

If I read it correctly, even if you clean them well and re gap, its still a hard start until you get brand new ones?

 

Switching brands seems easiest thing to try first, Let us know how you make out on your plug test.

 

RSTDdog

 

As far as cleaning and reusing not much luck. The gap is close enough to .035 that a light tap tightens them right back up. The cleaned and regapped plugs will run but not as smooth as new.

 

 

Mike,

 

I don't really know, but it's not normal in my experience. I have the NGK's in the Venture and I run many thousands of miles on a set. In fact, I've put 50k on my 87 VR (bought with 45k, now have 95k) and I think I've only replaced them once. And when I did, it ran the same.

 

I've put almost 100k on my 87 Virago. Ran NGK's sometimes, Champions sometimes. Never made a difference to running, starting, or MPG, and I track MPG for every tank. The only thing that consistently affects that is the attitude of my right wrist...

 

So when you pull them, they look good, right? Tan, still sharp edges on the electrodes? Yet there's a dramatic change in the starting. Weird. Does it affect other aspects of the way the engine runs - smoothness, power, MPG? The only thing I'd change, as someone suggested, is run the gap at .030-.032. If I'm not mistaken, the spec is .028-.032.

 

Jeremy

 

They are all light tan, dry and clean. Edges are are sharp and no burned off area. It would be hard to choose which one came from what plug if you mixed them up. They are that consistant. And as Gary said the specs are .032 to .035. I have played with the .032 gap and it does not fire up as well as the .035. These bikes are not known for having a stun gun spark. The wider gap is the better setting in my opinion.

 

 

About 5 years ago I was having a similiar problem with plugs except mine were giving me problems at about 5-6000 mi..Someone on this forum suggested using non resistor NGK plugs...Been fine ever since..Now I change them every winter just for GP at about 10-12K..

 

I have already switched from the DPR to the DP. No real difference in performance of life span.

 

 

So with that said, I suppose a try of a different brand may be next to see what happens.

 

I've got a new set of coils on the shelf and a "brand new in the bag" TCI I've been saving for a failure. Maybe time to swap them out.

[dingy]

I've got a new set of coils on the shelf and a "brand new in the bag" TCI I've been saving for a failure. Maybe time to swap them out.

 

 

That explains why. I was somewhat surprised you didn't show any interest in the Ignitech unit.

 

After all, you got a new shiny one, that had to cost dearly, and its rock solid technology, I think its based on an 8088 chip, 8 bit state of the art, 3 decades ago anyways.

 

 

Gary

[Snaggletooth]

That explains why. I was somewhat surprised you didn't show any interest in the Ignitech unit.

 

After all, you got a new shiny one, that had to cost dearly, and its rock solid technology, I think its based on an 8088 chip, 8 bit state of the art, 3 decades ago anyways.

 

 

Gary

 

Go ahead Gary.... poke away. I figured it was coming. And I have been following the upgrade with much interest. Just haven't jumped on as long as I have this pile of Commador 64 parts I'm good to go. LOL!

 

You should remember when I bought the new TCI. You made an offer on it also if I remember right.

[Al Bates]

Once a year the plugs get change, (make sure you don’t drive with the chock on or leave it on to long, not good for the plugs) oil about 7,000 miles, air filters every 2 years or when needed, tires I do a good tire check it seem I do change them early.

Over 100,000 on this 02 and always 2 up, Diane has around 60,000+ on the back seat.

[Gearhead]

The only other thing I can think of is kind of a long shot. Have you cleaned up all the electrical connections on the bike? I've found that many of the major connections get a little corroded in the connector or even where the wire crimps in. I've enhanced my grounds, some of the hot feeds and many of the connectors. On the major ones I've added additional grounds, resoldered some of the wires in, that kind of thing. On smaller connectors I unplug and plug, scraping the terminals, and putting back together with vaseline on them. It's helped certain things. If you're getting a weak voltage to the ignition system, maybe it's super-dependent on having great plugs.

 

Does this issue affect any other aspect of running besides starting? Is your battery good?

 

Jeremy

[Snaggletooth]

HeyJeremy,

 

I think the starting and charging system on this bike is a strong as it can get. The heart of the system is the DEKA AGM. Still running strong and stays fully charged all the time. It is monitored with a digital voltmeter installed in the dash. The charging system is based on an upgrade stator from Buckeye Performance and uses a Shindengen R/R recently installed with a dedicated wiring harness harness to isolate the charging system.

 

The wiring harnesses has had as many plug in connections as possible removed and soldered and shrink tubed to protect. Dielectric grease has been used on all remaining plug ins from the headlight bucket back to the rear light bar.

 

I ride this bike everyday, and since April this year it is the only vehicle I use. With the weather we have had it has been soaked, drenched and drowned repeatly this year. Never a miss or a stutter in the worst rains you can imagine.

 

BTW .... I have become a true believer in Fogg Toggs.

 

Actually I'm kind of on a quest to embarass my neighbor. He's says there is no way you can get a 6 month riding season in Nebraska. I'm hoping for 8 myself. He has trouble doing 3 months. Ya know.... a light weight! LOL!

 

But with that said I feel pretty confident I've got the electrical system nailed down.

 

And the spark plug issue has been pretty much the same since I got bike running back in '07 before all the work was done. So the spark plug issue has been consistant since then.

 

There have been no other problems that effect the operation or performance of the bike. Not even a noticable drop in fuel economy. I don't worry much about that until I do a long ride and push to see how well I can do on MPG. Best ever was 48 mpg on the road and around town I can beat it down to 38-39 keeping ahead of traffic. If I play nice it stays around 42-43 around town.

 

Kinda makes me wonder what detail I missed. I should not be carrying spare plugs within that range ya know. Go figure.

 

[dingy]

You should remember when I bought the new TCI. You made an offer on it also if I remember right.

 

 

You're kidding right. I am happy to remember the parts I bought, let alone the ones I missed out on.

 

The UPS truck automatically pulls over in front of my house, just so the driver can check his sheet to see what I have that day.

 

I bought a grab bag pile of VMax parts a week ago, there were a few neat things in there and I think I can flip a few on Ebay to get my money back.

 

 

Gary