Misfire on 2 & 3

[z1bman]

junk all the fuel in the tank milky fuel is not rite clean the tank thoroughly & use BP ultima but whatever fuel is in the tank if its contaminated would affect all cylinders not just 2&3

[Ginger Bear]

junk all the fuel in the tank

Makes an excellent weed killer!

[Mr Bump]

I'm happy to admit that this is only a suggestion and that lots of chaps here have more expirience than me - but here goes anyway: can you try rotating the cam on the ignition advancer by 180 degrees and swapping the coil low tension wires? This should run shouldn't it? and will then give you a fair clue as to where the fault is e.g if the misfire doesn't move to 1 and 4 it's not the hall sensors on the crank?

Olly

i dont think that will work the timing will be 180% out even if you swap the low tension leads on the coils ?

Well, because it's a lost spark system, any given cylinder gets a spark at the top of each stroke, so at the top of compression and the top of exhaust strokes.

Swap the cam on the advancer unit it triggers each hall sensor 180 deg out , so each coil fires at the bottom of the strokes, not the top, so a given cylinder gets a spark at the bottom of the intake stroke and the bottom of the compression stroke, so you gets all sorts of popping and banging but it won't run.

As both coils are 180 deg out swapping the coil LT wires over should make them fire at the top of each stroke again, shouldn't it??

This might have become a bit academic anyhow as a carburettor full of semen isn't going to work very well...

Who's been whacking off in yr petrol tank then? Have you got a teenage son? If you do perhaps you need to have a word...

Olly

[DavidZ1R]

Modern fuel with ethanol in does go milky when open to the air, and as the tanks are vented along with the carbs it could be that.

[Swiss Gaz]

Thanks again for the pointers guys. It was deffo only firing on 2 and 3 originally as starting from cold the exhausts pipes on 1 and 4 would heat up too hot to touch in about 10 secs whilst 2/3 were only just getting warm. Changing the fuel though did have a big effect although with all the fiddling I did with the wiring at the same time who's to say I didnt disturb something there as well. I am still not happy with the coils. They are new as the original ones were both cracked open. When bought them I had to send one back as it was duff from day 1. I am not convinced of their quality.

[Swiss Gaz]

Sorry, meant to put mis-firing on 2 & 3, but then I am sure you know what I meant!

[johny brando]

1980 Z1000 LTD B4 (Electronic Ignition) HELP!
Well, I think it is a misfire.... Looking down the trusty color tune you can see it periodically and what can can only be described as "spits" or misfires(?) on idle and only on cyls 2 & 3. Not all the time but enough for a lumpy idle and poor pickup onto the main jet. Bike has never run well since it was imported. Runs great when you open the throttle though with no back fire on the over run. Grin factor 10/10.
Now this to me points to blocked pilot jets given its ONLY on idle. However, you can adjust the screws to get a nice colour where your supposed to find it ie 1 - 1/8th out (or there about and cyls 1 & 4 like this setting). I have taken the carbs off more times than I can mention and tried to clean them out as best I can (high pressure brake cleaner through the pilot chambers and then a good air blow out.
Vacuum for all cylinders is OK.
Balance is OK between all 4.
Tried new 15/17.5/20 # pilot jets. All show same symptom.
Swapped over coils/plugs/leads with Cyl 1 & 4. All parts check good.
Wired George mod done with good 12v to both coils.
Cylinder head off and valves etc all checked.
Bike done less then 5K miles & I have removed all the emissions guff.

Is there anything that I have missed? The electronic ignition is set is it not? Why exactly the same symptoms on 2 & 3 when 1 & 4 run like a doozy and I have proved the coil etc is OK? What else is shared with the two cylinders... IC Igniter? Is there an advance and retard?
I am loathed to fork out to get the the carbs professional cleaned purely because I don't think it will help, I also dont think the carbs are flooding, but what do I know cos i am scratching my head!

Any suggestions folks?

Yeh ...there's no point asking for help if don't want to then take the advise ! If that motor has only done 5000 miles in it's life ...it's stood idle & likely with filled float chambers too & those float heights by the way... should be checked & likely reset too ..."use a vernier gauge.. it's easy" but this will not be your problem though ...not with the symptoms you give ! I'd obviously as a no brainer/matter of course fit new Plugs & Caps first & do the appropriate Voltmeter checks on both your ignition pickup's & the ignition resistor mounted next to the coils. If they come back OK & as you say it runs strong & clean at high end rev's ...then I'd be having your Carbs Ultrasonically cleaned (professionally ) as likely/almost certainly they are " Varnished " nothing other than this will work properly, the old congealed fuel in them has likely closed or restricted internal drilling's & quite often they will appear ok & clear .....BUT there likely not !!!! there partially clear & there's a big difference there ! Some times you just have to dig deep & it's always process of elimination rarely with this sort of issue can you nail the problem in 5 minutes. Good luck buddy. Johny B