GPZ500S Warm Starting?!

[iCraig]

Well a few of you may know that my GPZ has been playing up recently and keeps cutting out when warm and won't restart till its cold.

It was in St Helens at Millenium Motorcycles, but with them being so useless and having it for over a week and not touching it I decided to bring it back home.

So the problems still persist, though now the bike has redeveloped an earlier misfire it had too.

So my question is what could be causing this warm starting/cutting out/misfire problem?
A few friends have said it maybe the coils or something?

So does anyone have any ideas?

Regards

Craig.

[beans]

Have you checked the coils? old ones can often breakdown causing warm starting problems. Also what state is the battery in, i have a friend who's zxr 400 woulnt start after the cooling fan had come on,he used to have to wait for it to cool before it would start again. He changed the battery and its been fine ever since!
I would say try changing the coils and see where that get you.

[ZRX61]

Coils? why not look at cheaper alternatives first???

Is the choke sticking?

Loose connection someplace?

& try throwing some new plugs in it before ya change the $200 coils...

[iCraig]

This may make me sound stupid but I can't seem to get the spark plugs out, even with the supplied Kawasaki socket I can't see to get into the aperture.

[Guest]

[Kickstart]

Hi Craig

If you cannot get the plugs out then wander down at the weekend and I can wip them out (even have a spare set, as Charlotte bought some for hers on Saturday and for some reason they insisted on giving her 4 spark plugs).

I have never had any real problems with coils. Yes they do go wrong, but hardly a common occurance. Should be easy enough to check with a multimeter anyway.

Warm starting problems tends to suggest it is rich. As ZRX says, check the choke it fully closing. Clean the air filter. Check the carb diaphragms are not holed (although I would expect that to make it run lean). Even check that someone has not filled it with stupidly thick oil!

All the best

Keith
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[iCraig]

Erm, I would pop down Keith but I very much doubt I'd get to yours as I can guarentee it'd conk out on the M6 and refuse to restart!

[iCraig]

[Kickstart]

Choke would explain that, as would a dodgy needle valve in the carb (it would flood a little when parked, but not much as the vacuum tap would not allow anything past it so just the amount in the fuel pipe, but once cool this would probably evaporate).

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[iCraig]

I managed to get at the spark plugs today and I noticed the RH one was normal coloured and the LH one was black and covered in sooty kinda of covering.

I also managed to get to the air filter which to me smells like its been covered in petrol at some point recently, or is that normal that it smells heavily of petrol?

[Kickstart]

Hi

Sounds like it is running serious rich on the left cylinder. Tends to narrow it down to one carb to look at.

Air filters will often smell of petrol, but they should not be drenched in petrol. You should be able to wash the air filter on the GPZ.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[iCraig]

Also discovered the HT lead on the LH side is damaged too and the cap easily comes off.

I have now replaced the spark plugs but and have ran the bike fully up to temp and it'll restart straight away, but I can guarentee if I go out on the bike it'll conk out and refuses to restart.

I shall recheck the state of the spark plugs tomorow when I have more time, but does anyone fancy being on stand by with a trailer too if I do conk out as NCI Breakdown will refuse to recover me without charging me. I'll pay you if in the event your required?

[Kickstart]

Hi

That one plug is sooty tends to suggest it is not the choke, as that is a fixed linkage between the 2 carbs and would most likely fail with both open.

Only problem with picking you up is if you break down on the motorway when the police might not appreciate you waiting to be picked up, or non recognised recovery people collecting you. Breaking down coming off the motorway is far easier, but the A41 might be a more sensible route if you really expect it to conk out.

How loose is the spark plug cap? I know that Cradley Heath have no caps in stock as we could do with a pair of replacements in and Charlotte asked last weekend. Not sure if suitable ones can be easily bought without going through Kawasaki.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[iCraig]

Well its loose enough to come of in your hand, its currently taped up atm with insulator tape.

And I noticed the park plug I took out were DR8EA's and I have replaced them with what haynes recommended (DR8ES's) did I do right or are both of these the wrong set for the bike?

[Kickstart]

Hi

Old M&P catalogue says DR8ES for the GPZ (D9EA for the newer D model GPZ).

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Kickstart]

Hi

Pictures of the rotor for you.

Caution, the pics are quite large (1.5mb each), and still uploading as I type this.

https://www.alfa-pages.co.uk/temppicture/CraigRotor1.jpg

https://www.alfa-pages.co.uk/temppicture/CraigRotor2.jpg

https://www.alfa-pages.co.uk/temppicture/CraigRotorCover.jpg

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[iCraig]

Thanks Keith!

Regards

Craig