Life span of a spark plug?

[Gearhead]

Well, Mike, this is one of the weirder problems I've heard...

[Snaggletooth]

Well, Mike, this is one of the weirder problems I've heard...

 

Well, ya know.................. that ain't that first time that has been said about my bike.

[V7Goose]

Your first post was titled "Life Span of a Spark Plug?" The answer to that question is pretty simple (but not necessarily the answer to your problem).

 

Any standard plug in and engine using unleaded fuel should provide reasonable service for a MINIMUM of 20,000 miles, and generally anywhere between 30,000 and 50,000 miles. AFAIK, no plugs are particularly susceptible to damage from strange electrical issues with an engine, so nothing that might be wrong with your ignition should affect the plug performance (except weak spark). If your spark is actually good (and your posts suggest it is), then the only thing that can cause a plug to go "bad" is deposits from incorrect combustion.

 

Next step would seem to be an exhaust gas analyzer - even a simple CO test should identify any major issues there that you need to focus on.

Goose

[Snaggletooth]

Hey Goose.

 

That thought has come up before. A friend owns a service shop and has the equipment to do that type of testing. We talked about it in the past but he wasn't too concerned about it with the consistent burn I'm getting on the plugs. And the fact he isn't sure if the readings he would get would be very accurate without having the ports for the test probes. So it would be a "Shove 'em in the pipe and see what happens test." I got a Doctor like that.

 

But I'll talk to him again a see if we can try it and see what it shows.

 

It would be nice to get a longer usable life out of the plugs. I'd be happy to get a full season out of a set.

[V7Goose]

Well, the 2nd gens have individual ports on each header to sample the exhaust gas. I have no experience with them older things. If they do not have the separate exhaust ports, then I'm not sure what to tell you - I think you have a common collector that mixes all four pipes together? That makes it even tougher to tell anything from an EG analyzer. But if all your plugs are giving you the same problem, maybe sampling the exhaust at either pipe will tell you all you need to know?

 

Worst case, if you think you have different problems with individual cylinders, is to just remove the lower exhaust and sample directly from the header exit points.

Goose

[dingy]

The 1st gens have a port on each exhaust header. The front ones are about 6-8" ahead of collector on lower outboard side. The rears are just past the clamp that connects down pipe to extension from rear head. #10 mm metric head.

 

Be gentle they can be twisted off, but then no harm no foul, threaded portion still keeps hole closed.

 

Gary

[Snaggletooth]

Yep, with the collector it does complicate dialing in on a single cylinder. But with some tinkering between or during tests it should show any changes. So it should point the way if here is something way out of whack. Trial and error. Old school stuff.

 

I've got a full set of extra carb bodies that are headed in for ultrasonic cleaning for a winter project. So I'll probably go ahead and go through the cleaned set when they are ready and swap out the good parts and replace any questionable ones before I get into trying to dial them in any closer. Might resolve any issues with that alone.

[Snaggletooth]

Thanks Gary. I never noticed that. I'll throw her on the lift this weekend and take a look at that.

[V7Goose]

Thanks Gary. I never noticed that. I'll throw her on the lift this weekend and take a look at that.

The standard tail pipe probe obviously will not work for those ports. I just went to Ace Hardware and bought some aluminum nipples (short tubes in about the righte size) and cut threads on one end to put in the threaded ports. Then I connect the port to the analizer with a bit of EGR tubing instead of using the normal exhausts probe.

Goose

[Snaggletooth]

That why I love this site. Always a solution for a problem. Thanks Goose. That should speed things up.

[dingy]

Here is a picture of rear one, can't find a picture that shows the front one, probably more like 3" ahead of collector.

 

Gary

[bilko1]

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

And what are you running it the venture max? :detective:

[dingy]

And what are you running it the venture max? :detective:

 

Iridium NGK @ .032"

 

Bike starts within a couple revolutions with half choke when cold.

 

Ran them 6,000 miles last year and gap was unchanged when pulled out.

 

Last year was with stock coils. This year is with Coil Over Plugs, so it will be interesting to see if that changes gap any.

 

I will be pulling plugs this weekend to inspect due to jetting issues, which are not a suprise really. I sort of threw a dart when I rebuilt 35mm carbs over the winter as to jet sizing. I am running rich, almost for sure. Used a VMax stage 1 jet kit.

 

Gary

[Condor]

OK, been reading all the comments and have decided to go with the Iridiums for the '99. Why?? Even though there may not be any perceived performance boost, the longer life is appealing as it's a PITA pulling the tank to change plugs on an RSV. The fewer times I have to do it the better. Also if they do last longer they will continue to offer good ignition long after a set of standard plugs start to fade. I just ordered a set of 4 off the web for $6 bucks per. It may not be the best price, but I figured it was close...

BTW I'm running K&N's and Bubbs with no change in the jetting. The tips of the Bubbs are a nice deep chocolate brown. Seems like the jetting is good.

[bilko1]

I just checked mine, L R was loose And R F was loose. Bike has been sitting for aprx 18 mos while I found all the bushings for the swing arm and the pivits for the rear shock, also replaced the rear shock with a works unit.

The plugs rere NGK non rester, and a #7, they were put in when the eng work was done, I never looked at what they put in, This may be why I have a very high temp. reading. Bike used to run about half way up the guage no matter how I rode.

[dingy]

Few pictures of the gas sniffer ports on the 1st gens attached.

 

ID of the hole with the screw removed is a tad over .190"

 

Gary

[jasonm.]

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

Listen, I have the same non-resistor plugs you have DP8EA-9. Guess what 3 out 4, the internals went to hell at 3k miles. Why did I buy these???>...because the NGK restistor types 3 years ago did the same thing. Even after cleaning....They all are electrically OPEN... infinite resistance when tested= JUNK. I am now running 15 year old DPR8EA-9's(saved) NGKs w/25k on them. I used to change them every 20kmiles. Yah 20K because they always came out clean and working. All these old ones read 4k ohms.And work perfectly. NGK clearly has NOW changed something in manufacturing. They are basically NOW crap or turn to junk quickly! AKA fishing sinker.... ANd as others seem to be pointing out. Getting the bike EGA'd makes things better. But seriously ...don't trust NGK. Remove the spark plugs, clean them and use a multimeter "tip to top reading". I bet you get a surprise like what happened to me. After 30 years in electronics, I have never seen such a simple thing made so poorly. If someone does not believe me. I will be happy to send you one of the bad spark plugs to test yourself....no charge.

Edited August 23, 2011 by jasonm.

[V7Goose]

Frankly folks, I have seen absolutely ZERO evidence that there is anything wrong with NGK plugs at all. Virtually all of these bikes are running with NGK plugs - don't know how many thousands of them, but many thousands at four plugs each. And we have what, 2, maybe 3 people with a grudge against NGK? The odds are clearly in our favor!

 

But hey, what do I know? I like Champion plugs too - always have. And LOTS more people hate Champion plugs than hate NGK!!! But somehow I STILL manage to put 20,000 miles a year on my RSV (with NGK plugs) without a breakdown! Guess I'm just lucky. Here's hoping the luck continues,

Goose

[jasonm.]

Goose, I have been using NGK on my bike for 20+ years. Putting 20k on a set of plugs was no issue until NOW~! I changed them a few yesrs ago and odd things started happening. Again...something has changed. The bad start issue or like what I had, a sparking out of the cap that was partly caused by the spark plugs being electrically "OPEN" in their respective cores. Thus the coil had to have enough energy to jump two gaps. If you do not understand electrical testing of these...well, you may not understand. BUt now I truly cannot trust the newer NGKs. None of this is fiction. In fact the parts store had to take the resistor bad ones back because they failed in 2 months. I have the bad non-resistor plugs to prove it. Just because others have the same set up does not mean it's the best. Especially when the manufacturer does not tell you something has changed how they are made. Especially quality control. Maybe they are now made in China? What would you say to that? How many here have tested their spark plugs with a multimeter??? None, I suppose. Snaggletooth needs to "electrically" test his spark plugs. Clean them anduse a multimeter . The non-resistor type should read basically ZERO ohms. Resistor types should read 4to 5k ohms. Either that or his carbs are not set good. ANd he's fudging up the spark plugs in some way while putting on the miles....NGK has a tech support line. I may call them to let them know about the junk they are selling. I have spoken with them before on other things.

Edited August 23, 2011 by jasonm.