More idling issues.....

[osborne]

It idles high during the "warm up" phase. And it'll run for 8 or 10 minutes or so.....{I can have a smoke while Im waiting} longer if I throttle it up when it idles down and tries to stall. Throttling and Feathering it only gains me another minute or two of running time though. Then it stalls and wont start up for hours.

Hoping someone here sees and understands the symptoms I'm having and can put their finger on the culprit.

[raul10141964]

I see 3 possible causes
Valves are to tight resulting on lost compression on hat
CDI or coil fail on hat resulting on lost of spark
restriction on the fuel flow

[jonathan180iq]

I was leaning towards the valves too, but if they were too tight then the problem should be with starting, not so much once it's running. And he's saying that he can start the bike no problem with a single flick of the starter switch and he doesn't even have to use choke.

Did you ever fix your broken choke switch? That's another clue in this mystery. If it's flinging back into the closed position then it's never actually engaged. And I can think of maybe only 1 or 2 GZs that have ever come through this site that didn't need choke at start up. So that's part of the problem.

I also thought about the spark fail problem at temperature. This is not the same bike that had the CDI randomly fail, is it? While that's a possibility, you can easily rule that out by waiting for it to go into one of it's shut down modes and then testing for spark. Then you'd know.

When it refuses to start for several hours, it does turn over and at least try to start, right?

[raul10141964]

I work on Chinese scooters and I see similar symptoms when the valves are to tight
Watt happen is on cold the valves close but wend they expand on hat stay open lowering the compression

[osborne]

jonathan180iq;79468]I was leaning towards the valves too, but if they were too tight then the problem should be with starting, not so much once it's running.
That's kinda what I was thinking as well.

And he's saying that he can start the bike no problem with a single flick of the starter switch and he doesn't even have to use choke.
True, it fires up no choke, no throttle.

Did you ever fix your broken choke switch? That's another clue in this mystery. If it's flinging back into the closed position then it's never actually engaged.
I haven't bothered yet as it seems to work fine apart from a stiffer than usual return on the switch. The spring tension is toward the open choke position. While running, if I move it to or toward the closed position it chokes it out as one would expect.

And I can think of maybe only 1 or 2 GZs that have ever come through this site that didn't need choke at start up. So that's part of the problem.

I also thought about the spark fail problem at temperature. This is not the same bike that had the CDI randomly fail, is it?
No, it isn't.

While that's a possibility, you can easily rule that out by waiting for it to go into one of it's shut down modes and then testing for spark. Then you'd know.
Ill check that next. Assuming I find there's no spark while its in "shut down mode", what would that point to as a possible suspect?

When it refuses to start for several hours, it does turn over and at least try to start, right?
Yes, let it sit a few hours and it fires right up like nothing happened.

[jonathan180iq]

True, it fires up no choke, no throttle.
Did you ever fix your broken choke switch? That's another clue in this mystery. If it's flinging back into the closed position then it's never actually engaged.
I haven't bothered yet as it seems to work fine apart from a stiffer than usual return on the switch. The spring tension is toward the open choke position. While running, if I move it to or toward the closed position it chokes it out as one would expect.

Here you go: If the spring tension is keeping the choke in the OPEN choke position, then it's never turning the choke off. This would explain why your bike will start without problem and not need any choke - because it's always on - but it also explains why your bike starts running rough and will idle down and die once the bike is warmed up. Once warm, the stuck open choke is over enriching the circuit and keeping the bike from starting again.

I did this on accident one time and kept thinking I was running out of gas or that something terribly maleficent had embodied my bike and going to come next for my nuts. I then looked down, saw that my choke lever was left open because I'm basically an idiot, and closing it remedied the problem. (You also said it would idle high but stay running, which is another sign that the choke problem is the problem)




When it refuses to start for several hours, it does turn over and at least try to start, right?
Yes, let it sit a few hours and it fires right up like nothing happened.

What I mean to ask is that it's not like you have an electrical lockout. You can turn the bike over, it just won't crank, right?

[osborne]

sorry this took so long to get back. Here is my choke cable. In the 2nd pic you can see the choke plunger extended out because of the spring in the line. That corresponds to my choke switch being in the open {or default} position.

In the 1st pic you can see the plunger retracted, thus compressing the spring. This corresponds to me sliding the choke lever to the full "on" position. letting go of the lever allows the spring to decompress and pushes the choke lever back to the open {or off} position.

As I said earlier, this cable seems to be functioning properly. Is the spring supposed to be there, that is, is it a stock from the factory part? People keep telling me here that my choke lever shoudnt return to the open or "off" position by itself. Yet, that seems to be exactly what the spring is meant to do?


"What I mean to ask is that it's not like you have an electrical lockout. You can turn the bike over, it just won't crank, right?"
Correct......the starter cranks the motor but it wont fire up.


P1010013.jpg

P1010012.jpg

[chromedome195]

I am no expert my any means....but my choke works like this. I push it to the choke position. It stays there. As the motor warms, I gradually push the choke lever back in reducing the amount of "choke". It does not turn off by itself. After about a minute I no longer need any choke. This is on a 1999 GZ250.
I believe your choke does not work as it was designed to work.
Again I am certainly no expert.....but just comparing it to how mine works, leads to my conclusion.

[osborne]

Howdy Chrome and thanks for the reply. Can you clarify something for me? when you are sitting on your bike, in what direction do you move the choke lever to operate it? On mine, {a 2000} the choke has a small decal painted on next to the lever itself indicating open/off is away from me and towards the front of the bike. That is the "at rest" position of the choke lever. Choke on is back toward me as I sit on the bike. Thus I have to pull the lever back towards myself against the spring's tension to choke the motor. Again......there is something counter-intuitive about this arrangement to my way of thinking. The attached pic shows the choke lever at rest. All the way forward,


Also, thinking a bit deeper about this......moving the choke lever back towards me into what appears to be the intended "on" position, The plunger on the carb end of the cable is compressing the spring and actually getting shorter. That is, its retracting out of the carb. Releasing the choke lever allows the plunger to get longer and push further inside the carb.

Sorry for being longwinded in my description. I just want to me clear about the problem Im having.

[chromedome195]

It is pouring here and my bike is covered---or I'd check to be sure.
But I think it moves towards me to use the choke and away from me to shut off the choke. If it ever stops raining here in the future---I'll be happy to verify that.