Spark plugs kept coking up

[Spurioushamster]

Hi, please excuse me if this has been covered elsewhere.

I took my 2005 FZ6N on a solo trip round France and Italy, but when I was in Paris my engine started behaving very badly. It would fire very intermittently and if I didn't keep the revs up it would cut out.

I stopped by the side of the road, petrol tank up, airbox off, battery box off, spark plugs out, and sure enough they were covered in carbon. I brushed them off with my brass toothbrush and the bike ran fine for another 200 miles before happening again, then I had to clean them on average every 100 miles.

Does anyone have any idea what could be causing this?

Thanks

Phil

 

[dpaul007]

I want to say you are running rich, really really rich. It seems a bit excessive that you have to clean them every 100 miles. How's your air filter? Do you have a fuel management box thingy like a power commander?

 

[FinalImpact]

Pictures would really help!

Is there a BLUE cloud behind you or a BLACK cloud behind you?

Blue, check your OIL as it's burning it.
Black, you should be getting BAD MPG.

Install some Fresh NEW PLUGS, see this thread, (http://www.600riders.com/forum/fz6-technical/48874-cure-bad-vibrations-spark-plug-caps.html) and test the CAPS for OPENS.
If you can show us a picture, one like this would be good; showing the burn pattern on the plugs electrode.

You could have BAD fuel, No spark, or low compression from oil passing through the rings. If you LUG the engine and never REV it, that could explain the oil consumption and fouled plug(s).

Give us some details.....

 

[Spurioushamster]

Thanks for such a quick reply guys!

Before the trip, the air filter, oil filter and spark plugs were all changed out. I put in a K&N air filter and the recommended NGK spark plugs. It doesn't have a power commander or similar fitted.

If I rev it hard, it blows out a bit of black smoke from the exhaust, which I'm guessing is just the carbon being displaced from the cylinder. I don't believe it's burning oil, as the exhaust fumes are clear.

The bike has been sat up for a few months now, as I've been too busy with work to look at it. I'll try and whip the spark plugs out this weekend and take some photos.

Thanks again,

Phil

 

[TownsendsFJR1300]

If not the ECU isn't faulty, a cheap potential help would be adding some fuel injector cleaner(techtron), Seafoam, etc may help.

I'm wondering if the injectors are gummed up some, partially open (never fully closing) dumping fuel into the engine when it isn't needed...

A top end cleaner at the very least to blow that excess carbon, crap out would be very helpfull.

BTW, a wide open run, then kill the engine would give the most accurate plug reading for whats going on at WOT.


ALSO, did you oil the air filter per the instructions? If over oiled, it may be PREVENTING air from passing thru causing the rich condition.

 

[FinalImpact]

If not the ECU isn't faulty, a cheap potential help would be adding some fuel injector cleaner(techtron), Seafoam, etc may help.

I'm wondering if the injectors are gummed up some, partially open (never fully closing) dumping fuel into the engine when it isn't needed...

A top end cleaner at the very least to blow that excess carbon, crap out would be very helpfull.

BTW, a wide open run, then kill the engine would give the most accurate plug reading for whats going on at WOT.


ALSO, did you oil the air filter per the instructions? If over oiled, it may be PREVENTING air from passing thru causing the rich condition.

This is first I've heard of an FZ ever Going FAT (RICH) w/out a PC3 etc. Even then, when set to blubber rich, they don't foul plugs.

I vote over oiled air filter. Clean per manuf instructions and just lightly oil it or buy a dry filter until this issue is resolved. Have you ever had this issue before the filter?

 

[TownsendsFJR1300]

This is first I've heard of an FZ ever Going FAT (RICH) w/out a PC3 etc. Even then, when set to blubber rich, they don't foul plugs.

I vote over oiled air filter. Clean per manuf instructions and just lightly oil it or buy a dry filter until this issue is resolved. Have you ever had this issue before the filter?

I suspect it took, (as posted) several miles before it finally loaded up with excess carbon and fouled the plugs. Yep, I've never heard of the stock ECU going that rich.

+1 ^^ on either a NEW STOCK air filter or replace the old one (IF in decent shape) for testing purposes.

Randy(or Cliff), can the sensor in the CAT, now probably carboned up, send a signal to the ECU making the situation worse?

 

[FinalImpact]

I suspect it took, (as posted) several miles before it finally loaded up with excess carbon and fouled the plugs. Yep, I've never heard of the stock ECU going that rich.

+1 ^^ on either a NEW STOCK air filter or replace the old one (IF in decent shape) for testing purposes.

Randy(or Cliff), can the sensor in the CAT, now probably carboned up, send a signal to the ECU making the situation worse?

If it were out of range to compensate it would show an error. I find it unlikely to cause an ubber rich condition without an error present.

A huge FACTOR HERE, could be Excessive Plug Gap! As stated; OEM gap for the specified plug is 0.032". The Bike spec is 0.028" max. A simple oversight could cripple this engine if the spark jumps somewhere other than the plugs gap.

 

[ltdillard]

A huge FACTOR HERE, could be Excessive Plug Gap! As stated; OEM gap for the specified plug is 0.032". The Bike spec is 0.028" max. A simple oversight could cripple this engine if the spark jumps somewhere other than the plugs gap.

My manual states 0.6mm - 0.7mm (0.0236 - 0.0276 in). By OEM gap do you mean by the plug manufacturer? I was confused by your comment. I have a 2004 model. Thanks.

 

[TownsendsFJR1300]

The plug, OUT OF THE BOX is gapped at .032"

( http://www.ngksparkplugs.com/part_finder/motorcycles/step4.asp?id=3932&type=reg )

Spec's as you state are .024-.028". As the plugs wear the gap gets larger. I tend to gap at the lower to middle range for that reason.

If you didn't re-gap the plugs (or check them) to make sure their within spec, you need to do so now using a WIRE GAUGE, NOT A FLAT FEELER GAUGE.

As Randy points out, if the gap is widder than specified, the engine won't run at 100%, could misfire if the spark isn't jumping fully, etc...

Please post of they were checked for the gap, re-gapped or not.. And of course, if you end up re-gapping, how she runs..

Also, how as the air filter oiled?