Iridium Plugs Overheating + Pinking

I have been running my 1100 Cali (hydraulic lifter motor) using NGK Iridium plugs. Recently suffering mild pinking and overheatingof the plugs (black glaze on centre insulator).I have dealt with the obvious including a kinked fuel hose, but wondered if anyone else has suffered similar problems.

Did you have any of these problems with the old plugs? If the answer is ‘no’, bin the NGK’s Pinking is due to pre-igniton, could be the very thin centre electrodes are getting too hot and setting off the mixture prematurely.

The old plugs were the specified NGK’s, but conventional BPR6ES. Theoretically the iridiums have the same heat rating

As I’ve posted before I personally never had much luck with NGK’s. I remember did try some sort of thin pointy electrode types once, can’t remember what the verdict was but they came out again soon after. To be fair tho the NGK waterproof caps are ace. Although I notice that the rubber sleeve and grommet of new ones I got last year are IMO badly made, i.e. don’t fit very well, so much so that I reused those off the old ones that they replaced. Just for reference, Bosch W6DC is equiv. to BPR6ES, but actually is a slightly hotter plug (BP6ES also equates to W7DC). W6DC is spec.d for all 850/1000 models except Le Mans’es (W5DC / BP7ES).

Try 97 octane?

I was talking to mark at twiggers the other day and he now says its best to run your bikes on 97 Ron

I tryd iridium plugs in my 1100i cali thay worked fine till about 4000mls. then the pinking and misfire started I put standard plugs back in and she runs fine again, I haven’t a clue why,

20 years ago I put a pair of NGK triple Platinum electrode plugs in my Lemon.On the M6 going to Scotland it stopped 3 times.After the third time I put the old NGK BP7ES back in and was fine.Never bothered with anything else since.

I reckon these fancy tipped plugs are designed for modern car engines, which a Guzzi motor ain’t …

personally …when i come across iridium plugs …i replace them . UNLESS you drive flat out everywhere , or your engine runs vv hot, standard plugs are fine .

YOU ARE ALL WRONG! (and you are all CORRECT, at least in part). Thanks for the input though; gave me something to work on.All of the solutions offered will assist, but the source is the ethanol content of the fuel and a seldom ridden bike concentrating both ethanol and water (water is miscible in ethanol and the ethanol can concentrate itself if left standing). Increased ethanol increases the oxygen input which has to be dealt with by the injection system. Also more prone to pe-ignition, so the more aggresive (later) advance curves aggravate the problem.Nothing wrong with iridium plugs per-se, but they seem sensitive to this problem. Using 97-RON is a partial answer as is cooler plugs, but the injection systems on earlier 2000’s Guzzi’s cannot cope fully.Introduction of E10 sometime will be equally dodgy.There is a QinetiQ Report produced for HM Government that is quite illuminating. intend to research and experiment further…Please post if you have your own experience. (Wonder what the official Guzzi technical line is).

Stoneman2014-10-05 21:11:13

Thanks Stoneman - the QinetiQ report makes for interesting (worrying) reading.

I imagine we can expect increased political pressure to remove older vehicles from the roads in the future. Although that will facilitate a greater proportion of crop-based fuels, I very much doubt the environmental benefits will outweigh the need to scrap and replace perfectly serviceable (and very likeable) machinery. I don’t imagine any mainstream manufacturers complaining about it, though.

Besides, how much of our countryside do we want given over to growing crops for fuel? Not that the farmers will complain at the extra business, either…

I located this E10 compatibility listing from the MCIA - under Piaggio…

Two further pieces of information (Plugs this time): Plug selection, heat range and the interaction with ignition advance: can have your spark plugs in too loose, so that there is insufficient cooling heat transfer path to the cylinder head:  and … seems like you have to be disciplined and use the torque wrench instead of (“it is tight enough” spanner feel)

Stoneman2014-10-06 13:29:57

This explains why the cleanest running plugs are always on the S3 which is running with Tetraboost (see separate thread from a few months ago). Mind you, not an economic solution if you do lots of miles!

An interesting and useful article on Ethanol/MoGas (petrol) blends, fuel degradation, moisture and phase separation here., it is for marine users, but equally applicable to bikers laying up for the winter (or simply riding less often)BP’s explanation of phase separation is here:"What is
phase separation, and how do I deal with it?

significant amounts of water are present in a fuel tank with petrol that contains
ethanol, the water will be drawn into the fuel until the saturation point is
reached for the three-component mixture of water + gasoline + ethanol.

this level of water, phase separation could cause most of the ethanol and water to separate from the
bulk fuel and drop to the bottom of the tank, leaving petrol with a
significantly reduced level of ethanol in the upper phase (see Figure 1 below).
If the lower phase of water and ethanol is large enough to reach the fuel
inlet, it could be pumped directly to the engine and cause significant
problems. Even if the ethanol water phase at the bottom of the tank is not
drawn into the fuel inlet, the reduced ethanol level of the fuel reduces the octane
rating by as much as 3 octane numbers, which could result in engine problems.

The level
at which phase separation can occur is determined by a number of variables,
including the amount of ethanol, the composition of the fuel, the temperature
of the environment and the presence of contaminants. It is very important (A)
that the system is inspected for significant quantities of water in the tank
before using gasoline with ethanol and (B) to limit exposure of the fuel tank
to excess water. If phase separation has occurred, it is necessary to
completely remove all free water from the system and replace the fuel before continuing
operation. Otherwise, engine problems could occur_._"
Stoneman2014-10-07 13:02:39

+1 for not wasting money on fancy plugs, my S3 has always run well on NGK standard plugs.