Awful Engine Noise and Bike Won't Pull (at speed)

[Toddtr]

10 minutes ago, nhchris said:

Great news the problem is solved @piotrek

What I'd like to know is the WHY of it.

What caused the iridium plug to fail after 12 months? And what actually failed within the plug? 

Huuummmm.

If the pic of both side by side plugs are correct the iridium is much shorter. Would that not be an issue at higher rpm, tip being further away?

[2and3cylinders]

Now when I replaced my last set of iridium with the conventional OEM spec'd plug, they looked great (as did prior sets), and I think my mileage was better with them too.  Again and however, if you compare their reach, it's quite a bit less, and that has to mean something.

[piotrek]

19 minutes ago, nhchris said:

What caused the iridium plug to fail after 12 months?

I don't think the plugs actually failed. Maybe the 12 months of service altered the plug properties enough to affect ignition under certain conditions (A-mode at 7,000RPM). I installed a slip-on in 2019... but all else was the same. Would be interesting to know the WHY for sure.

[piotrek]

1 hour ago, Toddtr said:

Would that not be an issue at higher rpm, tip being further away?

Apparently, but only under certain AFR/timing conditions etc. I could redline the bike in STD and B modes without issues.

Edited May 18, 2020 by piotrek

[rockinsv]

Are the stock plugs NGK's, just not the Iridium's?

[Buggy Nate]

Yep. Stock plugs are way better than iridium.

[skipperT]

14 hours ago, piotrek said:

I don't think the plugs actually failed. Maybe the 12 months of service altered the plug properties enough to affect ignition under certain conditions (A-mode at 7,000RPM). I installed a slip-on in 2019... but all else was the same. Would be interesting to know the WHY for sure.

They were failing under certain operating conditions, which for whatever reason were A-mode above 7k. We can only “armchair DIAG” this situation as it’s very difficult to observe the firing voltages under those types of conditions - but an Ignition mate or a scope set up while riding and having the problem occur would probably provide some data. The shorter reach of the plug may have had something to do with it, or the tip or porcelain may be worn in such a way that is invisible to the naked eye but still affects the spark condition. Or as I mentioned before, A-mode may also have a bit more timing advance and that’s why it puts the ignition system under pressure and why the issue cropped up....

combustion temperatures also affect wear of the plug material and the ability of the spark plug to remain clean.  Maybe it causes premature wear of the iridium plug materials? Maybe NGK had a bad batch of Iridium plugs? Who knows. 

in summary, Yamaha recommends traditional spark plugs on US models for a reason.  In countries where it doesn’t spec that plug, we really don’t know enough about the other inner workings of the bike or the ECM to say they didn’t make another change somewhere (different coil, less advance, gasoline quality of the country, etc) to allow the same model to run an iridium plug. As Piotrek’s pictures show, they are clearly NOT the same plug.  

-Skip

 

 

[skipperT]

13 hours ago, rockinsv said:

Are the stock plugs NGK's, just not the Iridium's?

Yes. NGK CPR9EA-9 if memory serves. they really don’t need to be replaced every 8k mikes either - could probably go 12-16k miles before replacing under normal operating conditions unless a running condition crops up.

-S

Edited May 18, 2020 by skipperT

[duhs10]

24 minutes ago, skipperT said:

Yes. NGK CPR9EA-9 if memory serves. they really don’t need to be replaced every 8k mikes either - could probably go 12-16k miles before replacing under normal operating conditions unless a running condition crops up.

-S

I'm at almost 19k miles on the original set of spark plugs.... oops lol.

No issues, however. I'm going to get the valves done at 20k so they will be replaced then.

[nhchris]

31 minutes ago, skipperT said:

in summary, Yamaha recommends traditional spark plugs on US models for a reason.  In countries where it doesn’t spec that plug, we really don’t know enough about the other inner workings of the bike or the ECM to say they didn’t make another change somewhere (different coil, less advance, gasoline quality of the country, etc) to allow the same model to run an iridium plug. As Piotrek’s pictures show, they are clearly NOT the same plug.  

-Skip

The physical differences in the plugs, particularly the length, is striking.  I would think electrode placement within the combustion chamber is important. Stock plugs seems to place the electrode deeper into the combustion chamber.

WRT other variables: Flashing the ECU has the potential to alter all types of non-spec parameters into the combustion equation. Once an ECU profile is changed, might other operating settings be inadvertently effected?

Edited May 18, 2020 by nhchris

[betoney]

4 minutes ago, duhs10 said:

I'm at almost 19k miles on the original set of spark plugs.... oops lol.

I wouldn't worry about it, I have never replaced plugs with less than 22k miles and even then it was only because it was a part of the valve service.  The plugs aren't as fragile as the owners manual would lead you to believe.

[BBB]

37 minutes ago, betoney said:

I wouldn't worry about it, I have never replaced plugs with less than 22k miles and even then it was only because it was a part of the valve service.  The plugs aren't as fragile as the owners manual would lead you to believe.

Yep, I agree with that. The only time I would change them earlier is if I did lots of very short commutes, where you risk fouling the plugs. But if you get the bike up to temperature regularly then you should be fine.

I did replace mine though, but that was because I had the tank and radiator off when fitting AIS blanking plates and it seemed churlish to walk away from the chance while I was there.

[piotrek]

1 hour ago, skipperT said:

...in summary, Yamaha recommends traditional spark plugs on US models for a reason.

Pretty much closes the case for me. An incorrect application for the spark plug. It was operating on very margins of acceptable spec. Reason NGK selector tool would not output the plug as an acceptable alternative.

Edited May 18, 2020 by piotrek

[duhs10]

57 minutes ago, betoney said:

I wouldn't worry about it, I have never replaced plugs with less than 22k miles and even then it was only because it was a part of the valve service.  The plugs aren't as fragile as the owners manual would lead you to believe.

Yeah, I agree and am not worried... I was just being funny saying "oops."

[Dodgy Knees]

If an engine runs well...plugs are well.👍