Power surge when wet

[pointbreak]

Hi. I hope someone may be able to shed some light on my bike's engine behaviour in the wet.

Bike:
FZ6 Fazer S2 2008
17K miles
Full service history
Original chain and sprockets

Behaviour:
(A) Bike will surge forward for a fraction of a second.
(B) Engine appears slightly lumpy, not smooth or like the timing is out

Throttle grip action:
(C) With a steady throttle grip position
(D) Coming off the throttle / letting the grip roll forward

I only experience the following when riding in wet conditions:

(C) can result in (A)
(D) can result in (A)
(C) can result in (B)

I never get the above when it is dry.

Has anyone else experience similar? Thanks for looking.

[Kriswithak]

I get that sometimes normally when riding, the FZ6 isn't the smoothest ride down low, and with bad fuel it can be very noticeable.
You might find your being more careful and not sitting quite in the power zone in the right gears when its wet. I still have the stock tyres on my FZ and they are terrible in the wet till they are nice and warm, and I still find them really lacking compared to past tyres.
It could also be the humidity affecting the bikes running.

Otherwise it could be some kind of electrical problem with your throttle perhaps? I guess if water is getting inside it could be doing something bad, not exactly an expert in this area though.

[RJ2112]

I'd agree that the engine is not going to run as 'clean' and smoothly, below 5K RPM as above that point.

There is a 'dead' spot just off idle, due to Yamaha trying to meet emissions requirements. With carbs, it used to be called 'lean surge'. Idle is fine, then you twist the grip slightly and nothing changes, a little bit more, still nothing.... then a teensy bit more, and you get more than you expect.

If you are riding the bike in very 'low power' conditions.... slight throttle in damp sounds like this situation, you will interact with that 'lean surge' frequently.

It sounds counter to good practice, but give the same conditions a try with more RPM. Step it down a gear so the motor is spinning ~1K higher RPM than what you went with last time, and see if it's smoother.

[squirly]

make sure your air filter is clean very wet air is thicker but i do agree with the other replies here too. just my 2 cents!

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Thanks for your comments. The thing is my bike never used to have this problem and I have ridden in heavy rain before. This is an S2 bike so there shouldn't be the throttle problems that can be experienced on an older bike.
I considered the throttle position sensor (TPS) but the diagonostics on the instrument panel confirmed that the throttle range was 16 to 103 with no missed values in between when twisting the throttle.
Last night I looked at lots of threads discussing the ignition coil packs and decided to investigate the HT leads, spark plugs etc.
I removed all the spark plugs and I found there was an odd one out. The spark plug connected to HT lead numbered '1' (left of bike as you sit on bike) was 'dirty'. Also it had a smell which the other three didn't. Does anyone know why this might be?
[IMG]C:\Users\jules\Documents\IMG_0345.JPG[/IMG]
When I got my bike back from its last service, spark plug #1 chamber didn't look sealed by the HT lead plug. I rode my bike for approx. 3 weeks before pushing the HT plug all the way home. It's possible some wet got in, or some muck, and this caused the plug to be 'dirty' but the spark plug shows the entire thread is dirty compared to the others and I don't see how dirt and water could have made their way down the thread. Also it wouldn't explain why #1 spark plug had a smell and the others didn't.
I'll describe the smell as petrol or oil.
#1 spark plug does stand out from the others and would welcome your comments on why this might be.
I see two coil packs in front of the battery under the tank. Are there any tests I can do on these?

Thanks for looking.

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Spark plugs uploaded.

[RJ2112]

Originally Posted by pointbreak

Spark plugs uploaded.

I'd have to think the #1 plug was not all the way seated at your last service. Between the boot being loose, and the 'fouling' you see on the threads of the plug..... that's almost a given. Lots of moisture and muck to form an electrical path to ground somewhere other than where you want it.

The plug is pretty rugged, but it does seem to be that #1 is more fouled than the rest. The plug wire may have been wetted enough, to ground out the spark impulse before it gets delivered to the plug. High voltage can 'jump' a fair distance... works out to about 1mm/1Kv. 25Kv.... 25 mm to jump to ground.

Look at the rubber insulation on the plug boot, and the wire itself. You may see a black, burnt spot. If so, toss the wire and install a new one. Once the insulation has been defeated, it will continue to do so.

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Thanks RJ2112! To remove spark plug #1 I'm sure I had to use the same force as the others to initially loosen it which suggests it was fully seated but maybe it was the residue which I was breaking when loosening it.
The brown residue on the body of spark plug #1 scapes off but I'm still baffled as to how the entire length of the thread got contaminated compared to the others.
The ends of all the plugs look the same. Maybe the spark plug was installed like this or with oil on it.
I have looked inside the end of the plug boot and there are no signs of arcing or pitting. The boot looks the same as the other boots.
I suppose I should put in a new set of spark plugs check again.

[pointbreak]

Just read http://www.fz6-forum.com/forum/fz6-t...g-problem.html (FZ6S S2 Misfiring Problem!) with interest. My bike does not misfire when idling. But there is something going on with my #1 cylinder (same cylinder referred to as #4 in the link). There's other things for me to check in the linked thread. Thanks again to RJ2112.

[RJ2112]

You'll want to trace back along that wire, all the way to the coil to inspect the insulation. The burnt mark could be quite small.... as small as a pencil lead and cause the issue. Could be, all is well there.

The only way that the entire threaded portion of that plug can get that grubby, is if fluids leak in there from the outside.... especially if the plug has continued to fire and isn't any nastier than the others at the working end. The only way I am aware of for that to happen is for the plug not to have been properly seated in the head. The crush washer typically doesn't seal in that instance, which allows the migration along the threads. The other 3 look much more typical, some discoloration near the working end, and cleaner and cleaner the farther away from the heat you get.

With the FZ having the spark plugs in relatively deep wells, that rubber boot on the spark plug wire is critical to keeping the splooge out of the plug wells.... if it's allowing water to pool in there, it will wick along the threads by capillary action. IF the crush washer is not properly compressed.