My Z1100 has been parked up for awhile now.
Giving it a check over, bike starts but will not idle
On investigation, cylinders 1&4 are working, 2&3 are sparking but, using colour tune, are not firing. Temperature gun confirms that 2&3 headers are little more than cool.
Compression test shows 140-145 psi on all four cylinders.
Colour tune shows 2&3 firing once throttle is opened to more than fast idle speed.
I am guessing a blockage in the idle circuit of 2&3 carbs. But on another bike in the past I have had similar and it was caused by split o-ring on idle mixture screw.
Is there any other items that may be worth special attention when I open the carbs up, or indeed any thing else that I have not considered.
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Mikuni BS34's
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'Dying a'int much of a living, boy'
Outlaw Josey Wales
Member No. 555
Outlaw Josey Wales
Member No. 555
It does sound a bit suspicious with 2 and 3 not running on idle!
I usually strip them and go round with a tin of WD40 with the fixed straw and confirm that there is flow at every opening.
Bit of a faff but the filters above the float needle seats are a real pinch point for smolge coming out of the tank.
Another favourite is the jet pressed into the bottom of the float bowls and the slender brass pickup tube that they feed.
AL
I usually strip them and go round with a tin of WD40 with the fixed straw and confirm that there is flow at every opening.
Bit of a faff but the filters above the float needle seats are a real pinch point for smolge coming out of the tank.
Another favourite is the jet pressed into the bottom of the float bowls and the slender brass pickup tube that they feed.
AL
1981 J1
Have you tried spraying carb cleaner around carb to engine rubbers, also change plug around, I had lots of niggles on mine and she still starts up on 1 and 4 when cold, even after putting 300 miles on the clock. 
1981 KZ1000 K1 LTD
Farm Boy with an O Level in Metalwork and not much else.
Everything in Sussex is a She, Except Tom Cat and She`s a He.
Farm Boy with an O Level in Metalwork and not much else.
Everything in Sussex is a She, Except Tom Cat and She`s a He.
I did think of the coil serving 2&3, maybe the Sparks it is producing are not powerful enough
The coil passes the resistance tests specified in the shop manual. I will swap the coils and see if the problem moves cylinders. I did renew HT leads last year, so will do a check on those as well.
Anyway carbs are off, and waiting to take the tops off and have a spray with carb cleaner.
The bit that confuses me with the coil is that at higher RPM, colour tune shows 2&3 firing. I would think that coil or leads would show a fault under load, not at low engine speed. Unless of course someone can prove me wrong.
The coil passes the resistance tests specified in the shop manual. I will swap the coils and see if the problem moves cylinders. I did renew HT leads last year, so will do a check on those as well.
Anyway carbs are off, and waiting to take the tops off and have a spray with carb cleaner.
The bit that confuses me with the coil is that at higher RPM, colour tune shows 2&3 firing. I would think that coil or leads would show a fault under load, not at low engine speed. Unless of course someone can prove me wrong.
'Dying a'int much of a living, boy'
Outlaw Josey Wales
Member No. 555
Outlaw Josey Wales
Member No. 555
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I had a similar problem and it turned out to be the rectifier, worth checking!
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zorded wrote:What is the battery static voltage and the voltage across the battery when on idle?
What is the measured voltage at the coils when on idle?
Has it got a Dyna 'S' or the original ignition system?
Which coils does it have?
Has it definitely got the correct fuel levels in all four carbs?
AL
Right, finally got some time to myself.
Carbs.
Removed the carbs, checked for blockages with carb cleaner, diaphragms are OK, new O-rings on pilot mixture screws. Set up basic at two turns out which is right by the Kawasaki manual. Static throttle butterfly balance using a drill bit on all four carbs. Fuel levels checked .Reinstalled carbs.
Battery voltage:
Static = 12.93v
Ign on = 12.73v
Running = 13.50v
Coils
Standard OEM set up.
Pass the resistance tests in the shop manual.
Coil volts static = 12.53v on both coils
Coil volts running =12.85v between red wire and earth, 10.30v between green or black wire and earth on both coils
At the moment the bike starts and is idling after a fashion. Temperature gun now shows 1&2 getting hot, 3&4 cool, but I have not got as far as carb balance using vacuum gauges. More when I report back, comments in the mean time welcome.
Right, after a couple of hours on and off in the garage, looking through the colourtune, Cylinder one is rich at idle, but normal on mid throttle. cylinder two is similar. cylinder three is not burning any fuel at idle [but it is sparking] but does start working at mid throttle. cylinder four is similar to one and two.
So not sure what the problem on cylinder three is. The others I cannot seem to get any real change at idle through adjusting the pilot screws.
At idle the engine pops and farts like a goddun, but on mid range throttle it seems quite happy on all four and the vacuum balance gauges are all even.
'Dying a'int much of a living, boy'
Outlaw Josey Wales
Member No. 555
Outlaw Josey Wales
Member No. 555
Fuel level?According to the manual you should be able to measure battery voltage on both the red wire and the Black Green pairing also!
10.3v on the black / green wires looks a bit odd!
Maybe a problem with the IC ignitor as that is where they come from but not that confident around them as mine had 'S' fitted before i got it.
Setting up with a drill in the butterflies will not work properly as different cylinders give different amounts of vacuum albeit slight.
Really need to use a good set of gauges to be certain particularly with the CV's.
You should get a fairly pronounced but certainly very visible change in colour with the colourtune with as little as 1/2 a turn on the fuel metering screws.
They do pop / spit / fart / and cough a little until warm if you are in the right area for mixture.
They do prefer to be run a little richer on idle than the original manual suggests with our 'modern' fuels.
If you cant get it to fire on idle on any given cylinder on idle try richening it up by unscrewing the fuel metering screw to maybe three, four or more turns until it does.
If after getting them all running correctly on idle; one or more screws are far away from the 'two turns out' then that is likely where the blockage will be if there is one.
My spread of values was something like 1 1/2 to 3 1/4 turns and running perfectly at those settings.
Did you remove the pressfit alloy plugs and the pilot jets behind them??
If you have run it for any length of time whilst it is missfiring or if any plugs got soaked while trying to start it; bin them!!!
AL
10.3v on the black / green wires looks a bit odd!
Maybe a problem with the IC ignitor as that is where they come from but not that confident around them as mine had 'S' fitted before i got it.
Setting up with a drill in the butterflies will not work properly as different cylinders give different amounts of vacuum albeit slight.
Really need to use a good set of gauges to be certain particularly with the CV's.
You should get a fairly pronounced but certainly very visible change in colour with the colourtune with as little as 1/2 a turn on the fuel metering screws.
They do pop / spit / fart / and cough a little until warm if you are in the right area for mixture.
They do prefer to be run a little richer on idle than the original manual suggests with our 'modern' fuels.
If you cant get it to fire on idle on any given cylinder on idle try richening it up by unscrewing the fuel metering screw to maybe three, four or more turns until it does.
If after getting them all running correctly on idle; one or more screws are far away from the 'two turns out' then that is likely where the blockage will be if there is one.
My spread of values was something like 1 1/2 to 3 1/4 turns and running perfectly at those settings.
Did you remove the pressfit alloy plugs and the pilot jets behind them??
If you have run it for any length of time whilst it is missfiring or if any plugs got soaked while trying to start it; bin them!!!
AL
1981 J1
Thanks for the replies. Tomorrow....
I will check for any air leaks
Check voltage across the coils
Richen the mixture to 21/2 and then 3, and then.....
Pilot mixture screws were removed, passage blown through with cleaner, then new O-rings on the pilot screws,then refitted.
I have a couple of spare I/c igniters to try.
Guess I will buy some spare spark plugs as well
I will check for any air leaks
Check voltage across the coils
Richen the mixture to 21/2 and then 3, and then.....
Pilot mixture screws were removed, passage blown through with cleaner, then new O-rings on the pilot screws,then refitted.
I have a couple of spare I/c igniters to try.
Guess I will buy some spare spark plugs as well
'Dying a'int much of a living, boy'
Outlaw Josey Wales
Member No. 555
Outlaw Josey Wales
Member No. 555
OK so far
Removed No3 pilot screw, soaked the jet in carb cleaner and then blown through with air.
Voltage across the coils with engine running is 2.7v +/- 0.5 volts
I have backed out all four of the pilots to 2.5 turns
No3 is now firing on idle
Engine idling a lot better.
Now off again to fine tune each cylinder with colourtune, then check balance again.
Not sure what part of what I have done to No3 has worked though.
Removed No3 pilot screw, soaked the jet in carb cleaner and then blown through with air.
Voltage across the coils with engine running is 2.7v +/- 0.5 volts
I have backed out all four of the pilots to 2.5 turns
No3 is now firing on idle
Engine idling a lot better.
Now off again to fine tune each cylinder with colourtune, then check balance again.
Not sure what part of what I have done to No3 has worked though.
'Dying a'int much of a living, boy'
Outlaw Josey Wales
Member No. 555
Outlaw Josey Wales
Member No. 555
Right, I have put my tools down, and taken a deep breath. 
With the colourtune on No3, I could get a steady idle, but when blipping the throttle, the revs would hang, and slowly decrease to idle. So richened the mixture on all four carbs slightly, this helped with the revs hanging, but then I found it hard to set the basic idle without it dropping. If I increased the basic idle, it would then tend to climb away, then winding the idle down the engine would eventually stall.
This richer mixture was confirmed by all four plugs being blackened.
I then put the colourtune on No1. When the engine started, there was a couple of loud bangs through the exhaust [ as far as I know, unburnt fuel in the exhaust igniting ] but then I had petrol flowing from the overflow drain of No1 & 2 carbs. I am guessing the backfire has jammed the float valve open, or by co-incidence dirt has got in, although there is a filter on my temporary supply tank that I am using.Not sure of the significance of changing the colourtune over and the large backfire.
Like I say, drawn stumps for the day, will have another go tomorrow or Monday.
With the colourtune on No3, I could get a steady idle, but when blipping the throttle, the revs would hang, and slowly decrease to idle. So richened the mixture on all four carbs slightly, this helped with the revs hanging, but then I found it hard to set the basic idle without it dropping. If I increased the basic idle, it would then tend to climb away, then winding the idle down the engine would eventually stall.
This richer mixture was confirmed by all four plugs being blackened.
I then put the colourtune on No1. When the engine started, there was a couple of loud bangs through the exhaust [ as far as I know, unburnt fuel in the exhaust igniting ] but then I had petrol flowing from the overflow drain of No1 & 2 carbs. I am guessing the backfire has jammed the float valve open, or by co-incidence dirt has got in, although there is a filter on my temporary supply tank that I am using.Not sure of the significance of changing the colourtune over and the large backfire.
Like I say, drawn stumps for the day, will have another go tomorrow or Monday.
'Dying a'int much of a living, boy'
Outlaw Josey Wales
Member No. 555
Outlaw Josey Wales
Member No. 555
2.7v +/- 0.5 volts
You mean 12.7 volts i hope?
Whilst you were changing over to the colourtune plug your carbs were flooding the cylinder and then the exhaust hence the backfire when it eventually started!
You have either dirt on the float needle seat or the 'O' rings around the seats are passing petrol.
Remove the horseshoe clamps and if you can pull the needle seats out with youre fingers then the 'O' rings need replacing.
Tank and filters need flushing through too. Some of the fuel round here has tiny brown particles of softish material floating in it. Just enough to hold the needles open if it gets on the seat as it will just as the valve is approaching shutoff.
Have you cleaned out the pilot jets?
Not the; 'spring limited mixture adjuster screws' on top but hiding behind those tiny camouflaged alloy plugs in the float chambers?? The plug is about 5mm diameter with a seal round it and the jet is removed with a flat blade screwdriver.
If there is water /froth / dirt / corrosion / crap in there or between the needle jets (emulsion tubes) and the body, you will not get it to run properly until they have been ultrasonically cleaned to within an inch of their lives.
The hanging revs may be down to the carbs flooding, i take it you have it on the side stand with the airbox off.
I mention this because you would not be able to see that it was 1 and 2 that were flooding if you have the airbox on as there is no external overflow.
When they flood they pour into the airbox and cylinders at the same time.
You will probably have to colourtune and balance and colourtune and bal.... etc a few times as its' an itterative process not to mention irritating.
They say; bunsen blue is a correctly proportioned mixture but in practice i have found that; 'a little yellow' of this point works best for idle. Higher up the rev range is another matter.
If the plugs are coming out blackened it indicates incomplete combustion however it may also indicate it is not fully up to temperature!!!!!!!!!
Are all four choke plungers fully seated and positively held shut by the choke rod and the spring loaded forks?
Keep going you'll get there. Sounds like there are a few things going on at the same time.
AL
1981 J1
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