1978 Z1R Carburation Problem

[SP10mk11]

AAAAAAAHHHHHH

Where do i begin........i have gotten my Z1R back from having the head sorted out (valves,guides etc) all is well on that side of things.

When i put it in to this guy i said that it had a misfire just off idle when pulling away, he told me that i had the wrong bleed pipes, after this he then broke his foot and could not then test ride the bike for some time to test it out to try and sort out this fault.

So
i agreed to take the bike (as it will be months before he can ride again)

So with his recommendation i bought the correct bleed pipes with rubber seals all excited i fitted them, and hey ho the bike runs like a dream, big improvement all over the rev range..................but! (though it is not as bad) this fookin off idle stutter is still there

I have got standard mains (107.5) and standard pilots (15's) airscrew turned out 1.5 turns, if i set it too 1 1/4 it runs too rich (sooty plugs), the floats are at correct height, carbs are balanced blah blah.


the bike has electronic ignition from a mk2 Z1000 with suitable coils (nice big fat blue sparks), advance retard is working, bike is fitted with a marshal 4-1 exhaust

This problem has existed ever since i bought the bike, and it is driving me effin mad

I dont know what too look at next

Anyone any ideas


Fanx

Desperate in cornwall

[Pigford]

This stutter just off idle is NOT uncommon. Assume carbs are nice & clean & float heights, etc are OK
U got standard air box? The 4:1 will effect it a bit.
Just winding in the air screw a 1/4 turn should not make plugs sooty? This will only effect 0 - low throttle opening as u obviously know, but shouldn't make too much difference
Might be worth trying 17.5 pilots as if OK rest of range, mains are OK.
If std air box & filter, try restricting air flow a bit, see if makes it better or worse to give u a clue or even use a bit of choke

[Rich]

Make sure that the two pilot spray holes in the venturi under the engine side of the slides are clear, they cause it to stutter when just opening the throttle if they are blocked.

[SP10mk11]

Hello there

I have standard airbox but now have a K&N air filter instead of the standard one, but this has not changed the problem at all.
the plugs were always sooty before i changed the Bleed tubes, they are still a bit dark now but not as bad.

So my thoughts are not to richen the mixture, as i think the mixture has been too rich in the past.

When you ride the bike from cold this doesnt happen, but as the bike warms up it starts to stutter, so this is also why i think the mixture is too rich

Gary

[Pigford]

Ahhhh, OK, is it better when air screw is wound out 2 x or more

[SP10mk11]

Make sure that the two pilot spray holes in the venturi under the engine side of the slides are clear, they cause it to stutter when just opening the throttle if they are blocked.

Ok ill hae a look for them, i spent a lot of time today sucking and blowing and using carb cleaner nothing i blew through etc seemed blocked.
but i will have a look

Thanks

[SP10mk11]

Ahhhh, OK, is it better when air screw is wound out 2 x or more

i havent turned them out that far yet, but ill will try it out tomorrow .

thanks

[SP10mk11]

Ahhhh, OK, is it better when air screw is wound out 2 x or more

i havent turned them out that far yet, but ill will try it out tomorrow .

thanks

I have turned them out 2 turns it made no difference to the stutter just made it run a bit rougher so i have put them back to 1.5 turns

ahh the pleasure of it all.......pleasure?

[Pigford]

If all else is OK (carbs clean & balanced, timing, valve clearances, plugs & leads, good manifold rubbers, etc) worn carbs are probably to blame
Back in the early 80's my old A4 used to be bad pulling away and used to stall regularly, unless you gave her a good bit of throttle
These carbs are best with standard air box, etc and are not the best in cutting edge technology, espescially with cr*p modern fuel
Put it down as character

[bunnysZ]

mine was much the same , when i put on a 30yr old 4-2 exhaust on it , it sorted out the problem , more or less.

[SP10mk11]

Thanks to you all for offering your tips and advice on these BAS...D carbs on my bike.

Though the bike is runnning really well it still has this stutter, and i have tried everything suggested and more........and am giving up for now

as i might be able to borrow a set from another bike just to try them out.........

So cheers again.. for now


Gary

[SP10mk11]

Hello all again

Firstly a big thanks to Steve Cook for lending me a set of 28mm carbs to try out in place of my own set.

Unfortunately these did not sort out the off idle stutter.

having messed about with jets,floats, plugs, lead, timing etc etc i gave up and sulked for a while and then thought sod it if i cannot get this bike to run correctly on standard settings then ill mess around elsewhere.

I dropped the needles one notch, and hey presto! no more stuttering or sooty plugs...........kin ell months of effing around.

i even tried the relay power supply to the coils idea but no change there.

so there you are i have my old carbs back on needles dropped a notch, nice tan plugs and no off idle stutter.

So thanks to all again

And steve i will be sending your carbs back to you anon

Cheers
Gary

[phil churchett]

Glad to hear you sorted it out, [eventually], frustrating or what?

[Steve Cooke]

Alright mate, Good to know you've sorted it, why cant these things ever be the first things you try eh? perseverence has paid off well done.

Carbs in your own time no worries.

[rickman CRR]

"I dropped the needles one notch"

Gary

Did you drop the needles one notch from the standard middle position or had the needles been previously raised?