That is a distinct possibility - bad kickstand safety switch - maybe check and see if it is totally gummed up and clean it.

Bypass it and see if they cures the problem, then once you know that is it, replace it.

It should start in neutral not matter what. You shouldn't be able to start it in gear with the kick stand down.

Have you changed anything on the bike recently? Is there strong gas fumes from the exhaust when it idles rough?

Originally Posted by richgoat

mine's an '03 with 3500 miles on it.

Bloody 'ell. Typo?

Rob

Ok, so the kickstand switch checks out okay. But the rough idle and stalling when closing throttle points probably to the idle circuit or fuel mixture.

Yes it does smell strongly of gas when idling roughly.

On a side note, does anyone know whether this bike should start in gear with the clutch pulled in? It sometimes does, sometimes doesn't, but I can't imagine that this is related to the rough idle and stalling problem is it?

Originally Posted by rali

Ok, so the kickstand switch checks out okay. But the rough idle and stalling when closing throttle points probably to the idle circuit or fuel mixture.

Yes it does smell strongly of gas when idling roughly.

On a side note, does anyone know whether this bike should start in gear with the clutch pulled in? It sometimes does, sometimes doesn't, but I can't imagine that this is related to the rough idle and stalling problem is it?

It should start in gear with the clutch pulled in only if your kickstand is up.
Probably has nothing to do with rough idle.

Originally Posted by NFS240sx

It should start in gear with the clutch pulled in only if your kickstand is up.
Probably has nothing to do with rough idle.

Sorry, I may have miscommunicated the issue - the kickstand switch does seem to work as expected and the bike only starts in gear with clutch in if the kickstand is up.

There appears to be some oil-like sludge around the leftmost carb and all around the parts on the left side. Going to pull the plugs and am expecting one of them to be fouled up.

So I've narrowed the stalling issue down to some sort of switch/sensor. I would guess clutch safety switch or neutral switch. What happens is the bike will start in gear but it starts at various points -- sometimes starts with clutch all the way in, sometimes starts with clutch halfway out, etc. So it would seem like there is a fault switch involved somewhere...am I way off with this?

Originally Posted by rali

So I've narrowed the stalling issue down to some sort of switch/sensor. I would guess clutch safety switch or neutral switch. What happens is the bike will start in gear but it starts at various points -- sometimes starts with clutch all the way in, sometimes starts with clutch halfway out, etc. So it would seem like there is a fault switch involved somewhere...am I way off with this?

Even if the safety switch isn't working it wouldn't cause it to idle rough.
When was the last time you cleaned and checked your carbs? Did you check the air filter? Do you have the choke on or could the choke be stuck or the choke cable broke?

Air filter is clean, choke seems to be functioning correctly..not sure when carbs were done, just got the bike about 4 weeks ago. At this point, I'm more concerned about the stalling.

Tonight I checked the clutch safety switch (starter lockout switch according to the shop manual) and it works properly. So the only two things left that I can think of maybe causing a stall while riding are the neutral switch and/or the throttle position sensor.

I'm inclined to think the TPS might be bad or out of spec because on the electrical wiring diagram the TPS has a connection to the ignition circuit, which I guess could cause it to cut out?

The clutch and neutral switches are olny going to effect the starter circuit. If the bike is cutting out you need to check the kickstand switch. Try not shutting the throttle so quickly when when pulling the clutch in. It almost sounds like some one put a jet kit in it and they didn't set the needle correctly.

How many miles, when was the last valve clearance check and spark plug change, and carb balance?

If it was the sidestand switch it would not just occur when the clutch is pulled in, but at random times, especially with the bike in gear and the clutch out.

Pulled the plugs a couple days ago and they looked good, slight tan colour and no unusual wear. Didn't replace the plugs, just cleaned them. Not sure when the last valve check and carb sync was performed as I just picked up the bike (from a Kawasaki dealer, so I would assume they checked some basic things).

I will likely take it in and get the valves and carbs checked along with the other maintenance items. The bike has 28,000 miles and other than this issue seems to run flawlessly.

If the carbs were out of sync by any significant margin, would this be more noticeable at lower speed? I don't feel any strange imbalance or anything at higher RPMs.

I can of course ride around the problem by not closing the throttle so quickly, but I'd prefer to find the issue and fix it and ride without worrying if the bike is going to shut down. The symptoms I have are quite similar to the TPS failures described here (and the FZ6 was recalled as the bad TPS is a safety issue):

http://www.sportbikes.net/forums/fz6...ge-stalls.html

Quick summary of things I've checked that haven't fixed the stalling or erractic idle:

1) Plugs
2) Loose wiring
3) Cracked hoses
4) Kill switch
5) Clutch safety switch
6) Kickstand switch
7) Air filter
8) Throttle and choke cables
9) All fluids, including fresh fuel and seafoam for 2 tanks

Things to check still:
1) Valve clearances
2) Carb sync
3) Neutral switch
4) Throttle position sensor

Will post back as I rule out the remaining items (or, hopefully, fix the problem )

Anything missing from the troubleshooting list?

There are two bikes on the UK site which also have this problem. Mine has a K&N air filter but I can't remember if the problem started after it was fitted or not. Twice now the idle has dropped to about 800rpm and has had to be readjusted. I have synchronised the throttles twice during regular servicing and on neither occasion have they been very far out.

The bike has 20,000 miles on it. I haven't done the valves yet but will at the next service.

I don't think this is down to sidestand or clutch or neutral switches. I think it is some sort of air/fuel flow issue. I haven't had the time to go poking around under the tank yet. To be honest I'm hoping to log onto one forum or other to see a post from one of you guys saying yee ha! I've found it.

So hurry up.

You mentioned some sort of "gunk" around the carb(s)? Is it possible to have a vacuum leak somewhere? At the clamp that holds the carb(s) to the intake? Anything like that? You said it runs rough at idle and fine at higher RPM's, which is when manifold vacuum is at its highest, I believe. So if its pulling in more air than is intended for the amount of fuel given thru the carbs, it will miss and run rough. (which is the high HC's, or raw gas smell at idle.) A TPS will give the same symptoms due to, to much fuel in relation to throttle blade position(which is allowing a certain amount of air in accordance), or not enough fuel causing a lean miss and rough idle... I would check all clamps, vacuum hoses, etc. ( know you said no cracked hoses. but didnt say loose.) then do a voltage reading of the TPS at idle then progressively open it up then close the throttle. It should have smooth consistent voltage(not sure of specs). not jumping around. and also check it wide open to quick closed throttle. make sure it doesnt drop all voltage at idle.

In re-reading this, I realize I am not familiar with the 03-06 Zeds, and your saying carburetors. I am not sure they would have a TPS... maybe they do. If it has Throttle bodies, then yes. just my 2 pennies...