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Issues with Z1b

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chrisw1
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Issues with Z1b

#1 PostAuthor: chrisw1 » Wed Sep 26, 2018 7:02 pm

Hi ..... I have been out for my first ride on the Z1b ,This is the problem Bike starts easily warms up well runs well that is till you reach about 4000rpm in all gears then it breaks down starts to sputter and will not rev thru that range in fact will only slow down & dies off as it gets too much fuel, it is a little poppy thru the exhaust at idle & backing off
When at a standstill it will rev right to the red line ....... carbs have been rebuilt with all new jets etc but I am unsure what sizes until my carb guy gets back to me and I have a Dyna S ignition statically timed
I will be putting it on the bench tomorrow to find the problem but if anyone here has an easy solution I would be grateful

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Pigford
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Re: Issues with Z1b

#2 PostAuthor: Pigford » Wed Sep 26, 2018 7:05 pm

Will it not rev at ANY throttle position...…. like going along steady and gently winding her open?
Check ignition - advancer unit sticky maybe?
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chrisw1
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Re: Issues with Z1b

#3 PostAuthor: chrisw1 » Wed Sep 26, 2018 7:25 pm

Pigford wrote:Will it not rev at ANY throttle position...…. like going along steady and gently winding her open?
Check ignition - advancer unit sticky maybe?


It seems fine until you get on an open road .....at around 4300 revs it seems to stutter and the rev counter will not rise ..I fitted the dyna last week and it all seems to flip open and close with light finger pressure

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PAULJAC47
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Re: Issues with Z1b

#4 PostAuthor: PAULJAC47 » Wed Sep 26, 2018 7:37 pm

Chris sounds like a set up or advance prob,set the dyna with a strobe on full advance making sure it goes on the f mark,you say you timed it statically if find it best to do it dynamically and this will check as Mark says that it is advancing correctly.Have alaso known Dyna s units to be assembled back to front so you cant set them correctly,just a thought..Cheers Paul J(Bike looks Great bye the Bye)
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DogsbolloxofZ1B
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Re: Issues with Z1b

#5 PostAuthor: DogsbolloxofZ1B » Fri Sep 28, 2018 8:30 pm

I’d put miney on carbs, if I’m understanding correctly
you’ve gone past 1/4 throttle and on main jet.
Carbs may need looking at to ensure no port blockages.

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8 Valve Mark
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Re: Issues with Z1b

#6 PostAuthor: 8 Valve Mark » Sat Sep 29, 2018 12:58 am

DogsbolloxofZ1B wrote:I’d put miney on carbs, if I’m understanding correctly
you’ve gone past 1/4 throttle and on main jet.
Carbs may need looking at to ensure no port blockages.
..
if putting miney on carbs doesn't work, try putting eeny, meeny or mo on the job. m (sorry Mike, i had to.)

johny brando
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Re: Issues with Z1b

#7 PostAuthor: johny brando » Fri Oct 12, 2018 2:00 am

chrisw1 wrote:Hi ..... I have been out for my first ride on the Z1b ,This is the problem Bike starts easily warms up well runs well that is till you reach about 4000rpm in all gears then it breaks down starts to sputter and will not rev thru that range in fact will only slow down & dies off as it gets too much fuel, it is a little poppy thru the exhaust at idle & backing off
When at a standstill it will rev right to the red line ....... carbs have been rebuilt with all new jets etc but I am unsure what sizes until my carb guy gets back to me and I have a Dyna S ignition statically timed
I will be putting it on the bench tomorrow to find the problem but if anyone here has an easy solution I would be grateful


Hi ..don't know if you have found the culprit yet ? 3 things you can try which might help & give you direction . 1/ Check you have at least a constant 12 volts plus available at all times -Battery & charging system OK ? 2 /Leave the filler cap open next time you try it ...it could have a blockage in the filler cap vent hole line =causing a vacuum & stopping or stalling fuel ...followed by a slow fuel refill . 3/ If no change there ...& you have original ignition back plate & A/Retard unit or some one will loan you it =swap it out, & if all is then OK then you have your issue nailed ..if not & it's running the exact same go back to the carbs ...as the issue is likely there then . Good luck Bud. Johny B

guzziman56
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Re: Issues with Z1b

#8 PostAuthor: guzziman56 » Fri Oct 12, 2018 7:59 am

chrisw1 wrote:Hi ..... I have been out for my first ride on the Z1b ,This is the problem Bike starts easily warms up well runs well that is till you reach about 4000rpm in all gears then it breaks down starts to sputter and will not rev thru that range in fact will only slow down & dies off as it gets too much fuel, it is a little poppy thru the exhaust at idle & backing off
When at a standstill it will rev right to the red line ....... carbs have been rebuilt with all new jets etc but I am unsure what sizes until my carb guy gets back to me and I have a Dyna S ignition statically timed
I will be putting it on the bench tomorrow to find the problem but if anyone here has an easy solution I would be grateful

My KZ1100A with BS34 carbs. would rev to the red line at a standstill (opening the throttle really gently or giving it a hand full, and all points in between) ie. with no load, but would splutter, back fire and just would not run as it should under load once off idle. When opened up good and proper it was fine. I did all the checks as indicated above, cleaned the carbs to within an inch of their life, new diaphrams, float heights checked, new needle valves and seats etc etc. In desperation I raised the needles and guess what? - a completely different bike and a pleasure to ride.
Interestingly of course my USA bike only has one needle position so I have had to bodge with tiny washers for the time being, but it works.
For info. my bike has a Marshall exhaust, 132 main jets as opposed to 120 std's and has had the air suction valve system removed/blanked off. I assume the main jets were changed at some point to cope with the open pipe.
I hope this helps in some way.
1976 KZ1000A1, 1981 KZ1100 Shaft+Steib TR500 sidecar (ongoing), 1942 Motoguzzi 600U, 1948 Moto Guzzi GTV, 1952 Moto Guzzi Ercole (in bits), 1953 Nimbus, 1986 Moto Guzzi V65 Lario (in need of TLC), 1988 Moto Guzzi Mk V Le Mans


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