anoying intermitent bike gremlin

[DaveZX6r]

Ok so I have a 95 zx6r with 32,000 mi, that just had the valves
serviced. The past two seasons I've been chasing down a wierd
intermitent poor running gremlin.

The bike will be going along running fine and then it will start
to sound different. If I pull in the clutch and rev it, it will
rev a little slower than usual and it will sound anywhere from
just being a little rich to sounding like its only running on
two cylinders. Also when i let off the throttle the exhauSt
will pop, it doesn't do that when its running right, at least
not anywhere near this extent.

I pulled the carbs over the winter they were clean no
obstructions, I also pulled the petcock and fuel inlet screens,
both of which were completely free of obstructions and clean.
Also the tank was completely clean inside. In other words theres
no way this is a "crap getting stuck somewhere" issue.
I had been wondering if my fuel pump could be pooping the bed
but the popping in the exhaust suggests to me that its getting
too much fuel if anything, not too little.

At this point I'm starting to think its spark related, but I
have no way or knowledge of testing electrical parts. I don't
even know how to read a multi meter, and I don't have the money
to just go replacing parts one at a time.

One other thing is that the bike is not really holding
temperature that well. It will only warm up if its siting
still, and even then it will slowly but surely drop back down to
just above cool as soon as I start riding again. I allready
replaced the thermostat 2 seasons ago but it made no diference,
so I Just assumed it was the gauge, but sitting on the bike you
can deffinately tell there is a wide temperature swing so i will be
replacing the thermostat soon... again. I don't know if that could
be causing this or not but considering that the problem doesn't
show up right off the bat I doubt it.

If anyone has any ideas or even could help me diagnose it in
person that would be great. I just want to be able to ride with
out problems again. If anyone is up for helping out I will
gladly pay in beer, pizza etc.

[butcher bergs]

When's the last time the plugs were changed?

Does the running symptom occur when certain repeatable conditions are present or is it random? (Fuel level, duration of run time, etc)

When the carbs were apart, did you inspect the condition of the float needles?

Is the choke sticking on any of the carbs?

As far as electrical - Ensure the plug boots are pushed all the way on to each of the plugs. If you're certain that's all set, check the wires for any cracking. Check the plug boots for cracks, make sure your plug wires are fully seated into their respective coils. Typically plug wires are twisted into the boot as well as the coil. Make sure there isn't any corrosion on either end.

Let's forget about the temp issue for now but I have to ask, if you don't have the money to toss parts at it then why bother with another t-stat?

[Degsy]

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Fuel tank vent?

[DaveZX6r]

It seems to happen after a while of riding or possible with hoter temperatures. I ride in to work i n the morning when its cool and trafic flows fine and it seems to run fine. I ride it home in the afternoon when its hot and traffic moves a little slower and it acts up. And sorry I lost the first post I made and. Thought I got everything in it. The plugs were changed three seasons or about 16k ago and I checked them before last season when the problrem started they were fine then. Carbs were rebuilt same time as the plugs were changed and the needles were changed hen and yes I checked them when they were apart they're fine.

As for replacing the thermostat its 50 bucks and I know its not helping matters. But if you don't think it has anything to do with the issue I'm having I'll hold off.

[darkduc7]

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Fuel tank vent?

And change the plugs again.

[DaveZX6r]

How do I check the vent just blast it with compressed air?

[Degsy]

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Spare key in fuel tank. Ride until symptom appears then open fuel tank and see if problem instantly corrects itself.

[darkduc7]

Hmm, someone else should chime in, but the only way I've thought of is: when experiencing the problem, open the fuel tank fill cap, or at least partially to let it breathe. If after a minute the symptoms stop, bingo.

Personally, I just replaced mine on a previous bike, and it happened to work. Sorry I'm not of a ton of help, it just sounded like similar symptoms.

[DaveZX6r]

Don't have a spate key...ill go get one made.

[darkduc7]

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Spare key in fuel tank. Ride until symptom appears then open fuel tank and see if problem instantly corrects itself.

Doh! He beat me to it :-)

[butcher bergs]

It seems to happen after a while of riding or possible with hoter temperatures. I ride in to work i n the morning when its cool and trafic flows fine and it seems to run fine. I ride it home in the afternoon when its hot and traffic moves a little slower and it acts up. And sorry I lost the first post I made and. Thought I got everything in it. The plugs were changed three seasons or about 16k ago and I checked them before last season when the problrem started they were fine then. Carbs were rebuilt same time as the plugs were changed and the needles were changed hen and yes I checked them when they were apart they're fine.

As for replacing the thermostat its 50 bucks and I know its not helping matters. But if you don't think it has anything to do with the issue I'm having I'll hold off.

Personally I'd hold back on the t-stat for now. Your engine is building heat and regardless of whether or not the temp gauge is reading low-ish, it is still reading some kind of temp and is likely not related to your issue.....at least based on this internet diagnosis and the fact that it's plenty warm out at the moment.

16k is getting up there as far as spark plugs are concerned however I've gone as far as 26,000 on a set of plugs before running into random stalling issues.

When you say the needles were changed, do you mean the float needles? I ask because it's very rare for people to change those just for the sake of changing them.

When's the last time you sync'ed the carbs?

I forgot to ask earlier but did the issue begin to occur shortly after any repairs such as the carb rebuild?

With regards to a spare key, if having one made proves to be difficult/ expensive/ whatever an alternative is to ride until your issue manifests then *immediately* pull over, open the tank and listen for *any* whoosh-type sound. If the bike sits outside a lot then that is a good direction to consider.

[DaveZX6r]

Yes the float needles were changed, and they were done because half of them were varnished and my carbs kept flooding. That was immediately after getting the bike. As far as the plugs go like I said the problem manifested when the plugs were still in good shape, but I might as well change them again. The carbs haven't been synced since the rebuild. And I had a season of good riding after the rebuild which was the only repair I did, before the problem developed.

[stoinkythepig]

I bet it's one of the spark plug boots, one of the coils, or the pulsing coil failing when it gets hot. A little stime spent with a heat gun and an ohm meter might be enlightening.

[DaveZX6r]

Yeah... I'm like borderline electricity retarded. That would be something I'd need help with.

[Stoneman]

I bet it's one of the spark plug boots

It's either that or a spark plug wire...

[Degsy]

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I bet it's one of the spark plug boots

It's either that or a spark plug wire...

I don't think that bike has ht wires. I believe it's coil-on-stick.

[DaveZX6r]

It has an ignitor to two coils. Each coil has two wires. Its deffinately Not coil on plug.
Btw who makes a good set of wires. Don't need anthing crazy. Just a set that's not gonna suck two months later.

[duganc1717]

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Fuel tank vent?

I have had this happen before.

[DaveZX6r]

Tank vent is fine. Bike was parked outside work in the sun all day today opened up the tank, not a sound. Rode home, problem started, opened tank, not a sound. Started bike back up problem persisted...

[SVRACER01]

bad coil?
-it gets hot and starts breaking down.
-2 cylinders would stop firing or fire intermittently
-gas is still being pumped into the cyl so that would cause backfiring as unburnt fuel enters the hot exhaust pipes
-it would also rev slow since only 2 cyl are firing

[DaveZX6r]

Which is exactly what it does with the exception of breaking down. It won't die just run like ass. That is kind of what I've been leaning towards but didn't feel like replacing them with out knowing. Oh well. Someone here offered to help me go over it this weekend so hopefully we'll get it sorted out then.

[SVRACER01]

Which is exactly what it does with the exception of breaking down. It won't die just run like ass. That is kind of what I've been leaning towards but didn't feel like replacing them with out knowing. Oh well. Someone here offered to help me go over it this weekend so hopefully we'll get it sorted out then.

by breaking down i meant that the coil is breaking down when it gets hot and grounding to something other than the spark plug. not that the bike breaks down and stops running

[butcher bergs]

If it is the coil pack, it's likely creating an open when the symptom occurs.

If you have a service manual, see if it lists ohm ratings for the coils. I don't believe there are any special test procedures for this bike but it might be good to check into that as well.

Also, an infrared temp gauge will tell you which cylinder(s) aren't firing as the pipe(s) will begin to cool off, regardless of fuel being fed. I know a guy who has one.

[stoinkythepig]

So I looked up the pulser coil, unlike some wasted-spark ignition bikes, this one only has one pulser coil, not a pair. Since it runs (even if poorly) it's very likely not the pulser coil that's bad.

NGK might make replacement plug caps for cheap money. See: http://www.bikebandit.com/assets/dig...-Cap-Guide.gif and http://www.bikebandit.com/ngk-plug-caps?mg=9623&t=1

[DaveZX6r]

Update. Coils checked out ok. Plugs all looked ok just worn replaced them woth new iridiums. Wires looked like ass, replaced them. Checked my fuel pump relay and found it way out of spec. New one shold be here Thursday. I'll let you guys know what happens.