Z1OwnersClub GB

Hi chaps
I'm loooking for a little advice re main jets.
I have standard 26mm mikuni Carbs which was running ok ish with 115 main jets [plus needle set on the 4th notch down] along with k&n's filters plus marshall 4 In 1 deeptone exhaust, I did try to run the airbox with these jet's but it ran like a dog with jet black spark plugs.
The bike was running ok as was, but i would like to now run with the standard air box and the marshall 4 in 1 so i think i need smaller jets, any one got the same set up ?? what are you running with

Thanks Alan

107.5 main jet ,needle 5cn8-3rd groove, pilot jet 17.5, this is for the 1977 Z thou

HI Kev

thanks for the reply , the pilots are std 17.5, so if the standard jet size is 107.5 and i'm on the middle notch, this gives me 108.5 jet size, is this ok with the 4 in 1 exhaust

Alan

mirror man wrote:..... i'm on the middle notch, this gives me 108.5 jet size, is this ok with the 4 in 1 exhaust

NO

The main jet is 107.5 - irrelevant on needle position. The needle just alows the main jet to be in operation at different rates/different throttle openings.

A Marshall 4:1 is not as "free-flowing" as many pipes, so may not need much in the way of jetting changes - trial and error.

I assume you checked your coil 12v supply is good

Mark

NO not had a chance to check the coils yet , it's tough at the bottom

Alan

if it was running ok before you put the airbox on, try running it again with the k&ns and if it runs fine change jets and needles, the 1978 thou also had different ones.
main 105, needle 5dl31-3rd groove, pilot jet 15,
i will look in the garage tomorrow to see if i have some, but i have a feeling i have already given them to someone on here.

on my previous A1 i had 112.5s and it ran fine with the Marshall

kev/Mark

After my trial with the air box, it had to come straight back off, so the k&n's went back on and it ran ok , that was a fair while ago last year,
but now springs here [even though it's about -4c at the mo] i was looking to get it sorted ready for 2013 heat wave

i've defo got A1 carbs with 5CN8 needles and 17.5 pilots, so it's a question of do i drop down to 107.5/110 or even 112.5 as mr tiller had

Alan

check the rear of the carbs if they have been jetted for k&n's they may have the air corrector jets fitted remove these then it should be ok with std airbox

Pigford wrote:

mirror man wrote:..... i'm on the middle notch, this gives me 108.5 jet size, is this ok with the 4 in 1 exhaust

NO

The main jet is 107.5 - irrelevant on needle position. The needle just alows the main jet to be in operation at different rates/different throttle openings.

:

Can't quite understand this sequence of Q & A....
As I understand it.... The "Needle position" is really a metering of the main jet size. This would mean a 107.5 main jet, with the needle on the bottom noch ( ie. needle higher) would, in effect, give a larger main jet size, as Mirrorman suggests. Albeit, ... operation at different rates/different throttle openings as Pigford says.
RegardZ.

I'm confused again.

And my heads hurts!!

Garn 1 wrote:

Pigford wrote:

mirror man wrote:..... i'm on the middle notch, this gives me 108.5 jet size, is this ok with the 4 in 1 exhaust

NO

The main jet is 107.5 - irrelevant on needle position. The needle just alows the main jet to be in operation at different rates/different throttle openings.

:

Can't quite understand this sequence of Q & A....
As I understand it.... The "Needle position" is really a metering of the main jet size. This would mean a 107.5 main jet, with the needle on the bottom noch ( ie. needle higher) would, in effect, give a larger main jet size, as Mirrorman suggests. Albeit, ... operation at different rates/different throttle openings as Pigford says.
RegardZ.

The main jet will always be it's stated size, the needle meters the fuel at slide heights, and needle height will adjust the position at which the main jet starts to feed larger amounts of fuel, well i know what i mean anyhow

jimmock

any chance you could change those pants