GPZ500S - Running as rough as a badger's arse - now fixed.

[mchaggis]

After my GPz was sat in a torrential downpour all day yesterday, I think it managed to get water in the tank (yes, through a closed lid). It was having a huge amount of difficulty starting and kept stalling if I stopped revving. I managed to get about half a mile in half an hour before it stopped and wouldn't restart. Eventually after about 5 minutes it would start again (with a lot of coughing, spluttering and general misfiring) and I managed to get to a petrol station, where I filled up with fresh gas as I was paranoid about it running out of juice.

It started after about 5 seconds on the starter (which seems to be not disengaging properly, but that's a different matter ) and I managed to limp home (stopping to rescue my sister who had broken down on the busiest roundabout in Aberdeen on the way )

My problem is now that it sounds really loud and rough. It's also lacking in power. I recognise these symptoms from when my VT managed to get water into it somehow - loud and underpowered.

Is it likely to be water in the fuel as I suspect, or more likely to be something electrical? When my VT did the same thing, it never got better, even after hundreds and hundreds of miles when it should have been dry.
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[finpos]

It could be either water in the fuel or an electrical problem. Most likely electrical.

Electrical problem may fix itself if you give it a good soaking in WD40, but be very careful of anywhere there is a seal to keep water out - if any has got in, it's staying there. Look to see if the spark plug wells are full of water

When you put water in petrol, it sinks. So it'll go straight to the bottom of the float bowls and stay there annoying you. That's what the drains are for

finpos.

[DaveH]

Have you taken the plug leads out to make sure that the plug holes are not full of water?

Had that happen on the 900, suppose it could happen on any bike?

drain petrol from the carbs into a clear jar and see if there are two liquied with one resting on top of the other.


If full of water use a syringe to get all the water out, or failing that lots kitchen roll, or similar, to sook the water up...

[gixxersixx]

Check your electrics, take the connectors off and give them a good spray with wd, also spark plug caps. If you have managed to get water into your tank it would be at the bottom of your tank. If you do the above and has no effect drain your tank and put fresh fuel in.
Just want to check if your bike has old style k&n's fitted or if its standard airbox
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[hmmmnz]

my gs has its moments when there is heavy rain as well, in my case its electrical, damn those crappy coils, the connection are a bit corroided and with the extra moisture in the air/on the bike its enough to make it run like a bag of nails untill the coil heats up, i would have a look at you coils, (get a heat gun or hair dryer to them) clean all the electrical connections and then cover them in vaseline /petrolium jelly to stop moisture in the future.
i doubt very much its water in the tank, as the water will sink to the bottom and as long as your not running in reserve won't do any thing, even if it gets sucked into the carbs it'll just turn to steam. with a bit of coughing
good luck and keep us posted
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[mchaggis]

[finpos]

If you have no WD40, just do it the old fashioned way - pull everything apart, dry it with a cloth and put it back together. Unless you are really unlucky, you'll just need to look at the high tension stuff (coil, ht leads, caps, plugs) which is more susceptable to Scottish weather. Good way of checking all the rubber boots etc are in good order before the winter.

Put the bike of reserve, give it a shake then crack open the drain screws until real petrol comes out.

finpos.

[stinkwheel]

The plug wells are well drained. There is a hole through the side of the cylinder head between two of the fake cooling vanes to allow water to run out. Maybe just make sure they are clear by poking something through them?

I've never had a problem related to water on my GPZs and they were kept outside for years and have been ridden through some pretty heavy weather.

An old fashioned way of getting rid of water in the tank was to pour half a bottle of meths into a full tank of fuel and slosh it about a bit. It'll make it run SLIGHTLY lean for a while, but it will also make it run cooler because meths has a massively high octane rating.

[mchaggis]

Hrmph.

I've drained the carbs, in which there were water and a little residue. I've made sure the plugs drain fine (copious amounts of WD40 drain fine so water will). I've sprayed WD40 in all the electrical joints I can see, doused the coils in it and also the spark plug caps. I've cleaned the plugs (they look okay, if a little hot).

I've lubricated the clutch and the throttle cables (although the screws holding the RH switch gear together are made of cheese and have rounded nicely even after being soaked for several hours with WD40. .

I've poured about 300 ml of methylated spirits into about 10 litres of fuel, sloshed it about and ran it about a bit.

The result? It starts really easily, is a lot crisper on the throttle and the clutch is much lighter, which is nice. Oh, and my bike smells funny burning meths and vapourising WD40.

However, it's just as rough, even more vibey and just as low on power. Accelerating to 40 in first gear was quite possible before, now the same effort might just about reach 30.

The oil, filter and air filter are new as of about 200 miles ago. The plugs are about 3000 miles old and could probably do with changing. One spark plug cap doesn't grip the plug properly, so could probably do with replacing and the carbs need balancing.

All of that needed doing before it started having this problem though, so I don't think it's related. I'll get some more plugs tomorrow to see if they make a difference, I'll order a new HT lead and see if I can't balance the carbs.

Other than that, I'm stumped.
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I must not be a troll...
Mmmm, Guinness
Discovering the delights of Hammerite and a 3/4" brush.

[stinkwheel]

Balancing the carbs is always a good idea on twins.

[finpos]

Once you've found you have water in your fuel, it's worth draining the carbs a couple more times in case some dregs keep finding their way from the tank the the carbs.

finpos.

[Kickstart]

Hi

Yep, water can be a pig to get out. The GPZ500 does seem to be prone to getting water in the tank (hence why we never use reserve on Charlottes one).

This is what came out of the tank last time we drained it. The bottom 1" or so is water (I had decanted the petrol out by the time I too this photo).

https://www.alfa-pages.co.uk/TempPicture/GPZFuel.JPG

All the best

Keith
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[DaveH]

Had a similar sounding problem with the 750 I had. Bike would rev cleanly etc, until I moved off then it ran like a dog. Had drained the carbs a few times and that seemed to improve it, but in the end when I drained the tank I was surprised that the thing could fire at all, given the unidentifiable, multi layered, liquid that came out!

Rinsed the tank out, as described, and after that and draining the carbs once more, ran a lot sweeter

EDIT; Also had a SOHC CB750 that threw a plug out, took the head off and got it helicoiled and put back together for the thing to refuse to start. Was at it for weeks; everything seemd ok until my mate said to replace the plugs. Hadn't bothered as they were only a couple of hundred miles old; as soon as I replaced them the bike burst into life. It seemed that they were breakling down under compression as they had sparked ok when out of the head

[mchaggis]

An update:

I've balanced the carbs (they weren't actually that far out) and changed the plugs. I've topped up the coolant and bled the brakes. I doubt the last two have anything to do with it, but now it is running sweet as a nut.

The plug that was in was pretty filthy and fouled up, so I've put DR8ES plugs in rather than a DR9ES, I'll chop it later on to see if it's cleaner. I don't plan to be doing much high speed extended thrashing now that winter time is fast approaching, so I don't see it should be a problem. Various manuals and websites seem to recommend one or the other, it just depends on which you read. It now starts on the button, leading me to think it was the plugs which were the main problem once I'd got rid of the water .

I don't think I've been able to narrow it down to anything in particular, but the combination of carb balancing, meths in the tank, new plugs, the proper level of coolant in the header tank, dousing the electrics with WD40 and draining the carbs seems to have worked. A 20 mile high speed blast did it the world of good.

My two problems now are that a) I somehow managed to lose the fairing hatch over the header tank filler cap. I thought I'd tightened it enough but obviously not and b) The push throttle cable is buggered (really, really stiff) and I've fubared the screwheads in the RHS switchgear, despite soaking them in WD40 before hand.
____________________
I must not be a troll...
Mmmm, Guinness
Discovering the delights of Hammerite and a 3/4" brush.

[Blau Zedong]

Switchgear screws are a twat for turning to cheese. Drill the heads off and get the remainder out with molegrips one the switchgear is off. They are usually M4 or M5, replace with allen screws if at all possible.
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[DaveH]

Apparently the DR9EA is for the D model onwards and the DR8ES is for earlier ones.

Got supplied the DR9EA at the weekend from the shop, but decided not to fit them as they weren't the right spec and had no idea what difference it would make.....does anyone know what the differences area? Tried searching NGK's website, but not with much success...

[finpos]

https://www.spark-plugs.co.uk/pages/technical/ngkjpg.htm

[DaveH]

[mchaggis]

My brother got given the DR9ES when he asked for plugs for the GPz500 in a bike shop. When I took them out, they were filthy and had black deposits all over them. The bike is running an awful lot better with the DR8 plugs in it, but that might just be a function of simply having new plugs at this stage.

I guess the DR9 may not be hot enough for the earlier engine to self clean properly.
____________________
I must not be a troll...
Mmmm, Guinness
Discovering the delights of Hammerite and a 3/4" brush.